Auq. 11, 1887.) 



FOREST AND STREAM 



45 



Address all communications to the Forest and Stream Pnh. Co. 



POND LIFE. 



FEW people suspect how rich in life our fresh -water 

 ponds are at mid-summer. Any one who will collect 

 a few quarts of water from a weedy pond and place it in 

 a glass jar in a good light will be surprised at the number 

 of living tilings that may be seen swimming, leaping and 

 creeping about in it. Small and shallow ponds in which 

 many water plants are growing are best for malcing col- 

 lections. By taking the trouble to make a net of some 

 tine woven material— mosquito netting will _ do for the 

 larger forms — a much larger number and variety may be 

 obtained. They may be kept alive in the jar for a long- 

 time if a water plant or two be put in with them and 

 water is added daily to make up for evaporation. In 

 this way an interesting aquarium is made. 



Let us examine some of these lively little creatures and 

 find out where they belong in the great world of living 

 things and, as far as we can, how they live and move and 

 have their being. Suppose we begin with this little fel- 

 low, just large enough to he readily seen, which swims 

 along with a jerky motion and which is easily distinguished 

 from all others of its kind by possessing a single eye di- 

 rectly in the middle of the head. Its name is Cyclops 

 and it belongs to a group of small crustaceans called 

 Entomostraca, or, in common language, waterfleas. One 



notices its long antennas which seem to serve as swim- 

 ming organs as well as feelers, its short kicking legs, its 

 ringed abdomen or tail which terminates in two long 

 whips which seem to serve as rudders. If it is a female 

 cyclops we are examining our interest will at once be 

 centered in the two large sacks attached at the sides of 

 the abdomen and filled with what one woidd at once guess 

 to be eggs. Eggs they are, and being carried about by 

 the parent in this way their chances of development are, 

 no doubt, very much better than they would be if they 

 were set free in the water and exposed to the danger of 

 being devoured by some hungry creature. When they 

 have reached a due state of maturity they escape the sack, 

 and it has been found that their subsequent development 

 is through a series of remarkable changes, though not 

 uncommon in the group of animals to which they belong. 

 They pass into what is called the nauplius form, an or- 

 ganism very different in appearance to an adult cyclops. 

 The nauplius goes on developing, passing through a series 

 of moults, and finally the perfect animal is reached. 

 Thus the little cyclops has a truly wonderful life history. 



Even more remarkable is that of this other creature, 

 very much larger than the cyclops and belonging, as we 

 see at once, to the order of insects. We observe the wing- 

 like parts, though we know, of course, they are not true 

 wings. What they are, in fact, is gills, and we can see 

 the branching tubes wliich penetrate them and which 



EPHEMERA. 



really have just the same use as the tubes (called veins) 

 in the wings of insects. The only difference is that in 

 insects these tubes are filled with air derived from the 

 atmosphere, and in our animal with air derived from the 

 water. But I have already said that our animal is an 

 insect and I must hasten to explain that it is now in its 

 larval state, and that in its perfect condition it possesses 

 true wings and flies in the air. But it enjoys this liberty 

 only for a single day; the insect we are studying is one of 

 the' Ephemera, the class receiving its name, of course, 

 from the fact just stated. When their one-day existence 

 in the air is terminated they return to the water, where 

 the female deposits her eggs. These hatch into the larval 

 form we have seen swimming about, and in this state 

 persist until the time of flight, when a metamorphosis 

 into the winged form occurs. 



It need hardly be said that the larva? of many other in- 

 sects will be found in our aquarium. The mosqtiito spends 

 a part of his career in water, and judging from his rest- 

 less, jerky movements ho may make himself as disagree- 

 able in that medium as he does in the rarer one which he 

 inhabits later. The larva may be recognized by this 

 movement or by the bristled process, an organ of breath- 

 ing, which terminates its abdomen. The larval stage is 

 succeeded by the pupa stage, also spent in water. In this 

 stage the mosquito has a large head with prominent eyes 

 and a ringed abdomen terminated by two swimming 

 paddles. The body is bent a good deal and the creature 

 swims by a kind of rolling movement. 



If in making our collection we dipped pretty closely to 

 the bottom of the pond it is very likely a larva of the 

 dragon fly or devil's darning needle was caught. This is 

 quite a large creature, fully an inch long, of a black 

 color, and rather savage in its disposition, as w T e should 

 judge from the insect's name. By seizing it just behind 

 the head it cannot bite us, though it is not likely the 

 wound would be a severe one if it did. We notice the 

 wide head and prominent eyes, likewise the wide abdomen 

 with its pair of short rudimentary wings and respiratory 

 process at its end. The body is covered with a hard skin 



like that of beetles; one may often find these skins, dry 

 and empty, along the shore. They are what is left of the 

 larva after its transformation into the adult dragon fly. 

 Before the transformation the larva? crawl up out of the 

 water, their skins split along the back, and the perfect 

 insect escapes, leaving the skin behind. The cycle is 



DRAGON PLY LARVA. 



begun again by the dragon fly depositing its eggs in the 

 water, this it does by flying to the surface and dipping its 

 abdomen a little beneath. 



Other insect larvae likely to be met with are those of 

 water beetles. Some of them are quite large and possess 

 powerful biting jaws. 



Cra wling along the sides of the jar may be seen many 

 small worm-like animals. Some of them would doubt- 

 less prove upon examination to be insect larva?, but others 

 are true worms. Among the latter, perhaps, is the nais, 

 one of the most interesting objects for examination our 

 collection affords. To the naked eye nais is only a short 

 white hah, but when magnified a creature truly beauti- 

 fully and wonderfully made comes to our view. The 

 skin is transparent, so that all the internal parts can 

 clearly be seen. The body is made up of a series of seg- 

 ments, like an angle-worm. Indeed , the nais has a very 

 similar' structure to the angle-worm, and if the skin of the 

 latter were transparent so that we could see the parts 

 within, it would look much the same as nais does under 

 the microscope. We should see the long intestine run- 

 ning through the segments like a string on which beads 

 are strung, the delicate blood vessels constantly pulsating 

 and so driving along the white blood contained in them, 

 the rows of bristles wdiich form the legs and which fit 

 into pouches in the skin, and finally, if we looked sharply, 

 the very curious breathing organs wiiich are like funnels 

 — a pair in each segment — the large inner end being sur- 

 rounded by a row of vibrating cilia which keep up a cir- 

 culation between the fluids in the body and the water 

 without. The way Nais multiplies itself is very curious; 

 it simply divides into two parts by a break in the middle 

 of the body, each part soon becoming a new and perfect 

 animal. As this is the natural way for nais to reproduce, 

 we are the less surprised that its near relative, the angle- 

 worm, is able to undergo cutting in two without loss of 

 life. 



Among other worms that may be present, these small 

 dark flat ones attached to a stick or dead leaf, perhaps 

 may deserve a moment's notice. They belong to the in- 

 teresting group the Planaria. One notices the two black 

 eye spots and the dark area in the middle of the body 

 which represents the stomach and which has very many 

 small gastric canals running out from it. These little 

 creatures seem lowly enough, but one finds here as every- 

 where a perfect adaptation to that place in nature which 

 they occupy. Witness the organs of defense with which 

 they are provided, short, stiff rods concealed in the skin 

 and shot out in great numbers when they are irritated. 



Speaking of stinging organs we are reminded of the 

 little green (or brown, it may be) hydras attached to our 

 jar. This is a classic animal. In 1744 Trembley, a Swiss 

 naturalist, did those experiments with it which have se- 

 emed its fame for all time. He showed that the hydra 

 can be cut into small pieces, either lengthwise or cross- 

 wise, and each piece will grow into a new animal. Fur- 

 thermore he showed that the creature can actually be 

 turned inside out, so that its stomach-lining becomes its 

 skin and vice versa, and no apparent inconvenience is 

 suffered by the change; it goes on catching and devour- 

 ing prey as if quite unaffected by its evagination. Any 

 one who does not know the hydra may easily recognize 

 it by its long slender body, one end of which is attached 

 to some object and the other provided with six or eight 

 long swaying arms or tentacles. It catches its prey — 

 minute plants and animals — either by grasping with the 

 tentacles or by stinging them with thread cells, precisely 

 like those of jelly-fishes. It is very interesting to watch 

 the movements of a hydra. It slowly sways its body to 

 and fro and thrusts its arm about in "its search for food. 

 Under a slight irritation it quickly contracts its body into 

 a small rounded mass. Commonly one can see young 

 hydra growing out from the parent-like branches of a 

 tree. The hydra can readily be seen with the naked eye, 

 being a quarter to half an inch long when expanded. 



All the forms of life thus thus far described are large 

 enough to be easily seen without the help of a glass. 

 There are many others which can be discerned by the 

 naked eye, appearing as minute floating specks, but 

 which require a microscope for then- examination. Then 

 there are very many other's which are far too small to be 

 seen at all without artificial help. Provided with a micro- 

 scope one could spend a very long time in studying the 

 wonderful forms of life contained in our aquarium. It 

 would be too great a task to attempt to give an idea of 

 the number, variety and beauty of the living objects that 

 would be found. A sketch of the life found in fresh- 

 water ponds would be quite incomplete without some 

 reference to the plants that are always found in them. 

 Here again we must limit ourselves to a few of the most 

 common. Let us begin with one that is almost invaria- 

 bly present, and that will be recognized under the name 

 of pond scum. Every one has noticed the green or brown 

 patches that float on the surface or are attached at the 

 bottom and sides of the pond. They are not very 

 attractive forms of plant life to the ordinary observer, but 

 when one has once learned about their fife history, they 

 will always afterward be of a good deal of interest. There 

 are many kinds of these plants; let us take one of the 

 most common, the Spirogyra. It looks somewhat like a 

 green jelly when viewed in masses under the water. 

 But if a little be taken into the hand it will be 



seen to consist of many very fine green threads 

 closely interwoven so as to form a kind of felt-work. 

 These threads have a surprisingly beautiful appearance 

 when examined un der a magnifying glass. They are seen 

 to consist of rows of oblong cells placed end to end, each 

 consisting of a delicate transparent case wound about on 

 the inside by green bands, like the threads of a screw. 

 For some unexplained reason that portion of the matter 

 contained inside the cell which has been stained green by 

 chlorophyll takes on this spiral form. On a sunshiny 

 day the cells are constantly growing in length and after a 

 time cross-partitions are formed in each cell, each one 

 thus giving rise to new ones. When the strings have 

 reached a certain length they break into pieces and each 

 piece going on growing as before, it is understood how 

 rapidly pond scums extend themselves. In the fall of the 

 year they die away, but in the spring they appear again 

 in fult vigor. The manner in which they are preserved 

 during the winter is worth studying as illustrating a pro- 

 cess common to many waterplants. Early in the summer 

 the plants form what are called zygospores which fall to 

 the bottom of the water and remain there in an inactive 



POND SCUM. 



condition until the next spring. Then, under the influ- 

 ence of warmth and light they grow into new plants. In 

 the Spirogyra a zygospore is formed by the union of two 

 cells of contiguous filaments, this union being considered 

 a sexual process. 



Quite common in midsummer is the very curious little 

 plant called the volvox. To the naked eye they appear 

 like little green balls slowly rolling through the water. 

 They really consist of a mass or colony of cells in the 



form of a hollow sphere. Each cell is provided with a 

 pair of vibrating cilia which project into the water, giv- 

 ing the ball a hairy appearance, and by their movements 

 propelling it through the water. In the hollow of the 

 sphere other smaller balls may be seen, and examination 

 shows that they are precisely the same as the larger one, 

 forming an instance of life within life. After a time these 

 smaller ones escape and begin a career of their own. A 

 friend of the writer says that he saw many of these plants 

 in one of the Adirondack lakes a few years ago at about 

 midsummer. They were so thick that water could not be 

 dipped up without catching many of them. 



Another curious plant common in ponds is Hydrodict- 

 yon, or the water net. It consists of a tubular net com- 

 posed of very many elongated cells attached at their ends. 

 Sometimes the net is 10 or 12in. long, and the cells one- 

 third of an inch long. In this plant, too, a miniature 

 plant (in this case a net) is formed inside the parent and 

 finally escapes as a new plant. 



Of the larger plants growing in ponds Chara, which 

 has a very interesting history, is quite common. It may 

 be recognized by its slender tubular stems to which whorls 

 of needle-like leaves are attached at regular intervals. 

 The portion of stem between two whorls consists of a 

 single large cell surrounded by many small ones arranged 

 spirally about it. Sometimes one can see in the large cell 

 the movement of its thick fluid contents. It streams up 

 on one side and dowm on the other with a slow, steady 

 progress — a form of motion in plants which has been 

 studied a good deal by botanists. Where the leaves unite 

 with the stem may be seen the reproductive organs. They 

 are of two kinds, one produces free-swimming male cells 

 and the other female cells. The former swimming about 

 in the water meet with and fertilize the latter, which then 

 become surrounded by a hard case and finally fall to the 

 bottom of the water. There they remain until the com- 

 ing of conditions favorable to then- germination, when 

 they give rise to a new plant. This plant, however, is 

 not like the original Chara, it is a simple growth consist- 

 ing of a single row of cells, one of which, after a time, 

 becomes the starting point for the growth of the more 

 complex sexual plant. 



Many other plants, not less interesting than these 

 named, are common in our ponds. Here again the mi- 

 croscope would reveal to us an unexpected abundance. 

 The green slime that coats the surfaces of stones at the 

 bottom and the film that gathers around the stems of the 

 large plants are very rich in microscopic plants. 



To the plants in ponds is due the preservation of the 

 purity of these waters. The noxious products of the 

 decomposition of dead animal tissues (for where is so 

 much life there must be a corresponding amount of death) 

 are in large part absorbed by the growing plants. Fur- 

 thermore, the plants give off gases to the water which 

 keep it sweet and capable of sustaining animal life. Thus 

 there is a mutual dependence between the two great 

 famihes of animate nature. S. 



A Sparrow Terrier. — Washington, D. C. — There is a 

 black and tan terrier of peculiar ability in this city that 

 is distinguishing himself by extinguishing sparrows. He 

 belongs to a street car driver and accompanies an open car 

 to and from the Navy Yard to Georgetown. Sighting a 

 bunch of sparrows the dog goes for them like a flash, 

 seizing one, which he quickly kills and carries a short 

 distance, then he drops it and goes for another bunch. 

 He has been known to kill six on one trip, and at this 

 rate could round up with a record of twenty-five or thirty 

 a day. In spite of the fact that sparrow-s are so numerous 

 and that there is much prejudice against them the dog is 

 unpopular. Threats of kilting him are frequently made, 

 while passengers express their dislike of the dog and 

 sympathy for the birds. — J. C. B. 



