164 



KNOWLEDGE. 



[July, 1903. 



Ilie Goat's-beard (T. praiensu), close at mid-clay. The 

 Goat's-beard being a common plant, this habit has been 

 much commented on by the older writers, and has earned 

 for it the name of " John-go-to-bed-at-noon." Same of 

 the larger members of the Dandelion group vie with the 

 Thistles in elegance of form. This is esp^-ially true of 

 the Sow-Tbistles ; a well-grown specimen of Sonrhus asper, 

 with its stout hollow columnar stem, beautiful leaves cut 

 and spiny, with spiny lobes clasping the stem in a curious 

 spur-like fashion, and branching inflorescence, forms an 

 object on which the eye of the plant-lover will rest with 

 admiration and with pleasure. 



The Hawk weeds (Hieracium) form a remarkalile and 

 bewildering groiip of allied forms, in regard to which, as 

 in the Riibi, the term " species " is very difficult of 

 application. Between one end of the series and the other 

 — say between the single-headed alpine section and the 

 tall much-branched H. boreale and its allies — a much 

 wider gap exists than between the extreme ends of 

 Rvbvs fruticosus, but nevertheless the gaj) is completely 

 bridged over by intermediate forms, so that classification 

 becomes nigh impossible. The Hawkweeds are mainly 

 plants of mountain rocks ; all are herbaceous perennials, 

 with simple leaves and yellow flower- heads. 



Our native Contposltc'v are, for so large a group of plants, 

 singularly devoid of properties or uses. Most of them are 

 harmless jilants, and the stems or leaves of a good many 

 have formerly been used as food, either boiled or as salads. 

 A good many are of some use as tonics ; a few are febrifuge, 

 or vermifuge. The fleshy root-stocks of the Elecampane 

 (Inula Heleiimm ) are still sometimes candied ; the Flea- 

 bane [Pullcaria dysenterica) was formerly, as its name 

 implies, used in cases of dysentery. The Stinking 

 Chamomile (Anthemis Cotula) is acrid, and its foliage will 

 raise blisters on the skin ; while the Strong-scented Lettuce 

 (Lactuca virosa) has milky juice that is acrid and narcotic, 

 and has been used as an opiate. The Compositie c&n claim 

 to supply, in Colt's-foot, Groundsel, and Thistle, some of 

 the most persistent and troublesome weeds that occupy 

 the attention of the British farmer or gardener. By far 

 the most useful of the native species is the Dandelion 

 {Taraxacum ojjicinale), whose roots possess diuretic and 

 tonic properties, and are still much in favour in 

 pharmacy. 



Conducted by M. I. Cross. 



POND-LIFE COLLECTING FOR THE MICROSCOPE. 



By Charles F. Rousselet, f.r.m.s. 



{Continued from page 14L) 



The group of attached forms of Pond-life comprise such 

 Infusoria as Carchesiuin, Epistylis, Zoothamniuiu, Stentor, etc. ; 

 Rotifers such as Melicerta, Slephanoceros, Flosciiles, etc. ; Hydra, 

 all Polyzoa and Sponges. In searching for these forms, a 

 quantity of pond weeds, or rootlets, are brouprht on shore with 

 the cutting hook, and selecting some likely-looking, fairly clean 

 branches, but not the newest growth, one twig after another is 

 placed in the flat bottle in clean water, where it can be examined 

 from both sides with great ease, both with the naked eye and 

 the pocket lens. The tree-like Torticella colonies : Epistylis, 

 Zootkamnium, t'arche.<iuiu, the trumpst-shaped !:>leiiturx, the 



Crown Rotifer Stfphanoanis, the tubes of Melicerta and 

 Limnias, the various Polyzoa, also Hydra and Sponges, and 

 many others, can at once be seen when present, and in this way 

 good branches can be selected and placed in a separate wide- 

 mouthed collecting bottle containing clean pond water. A little 

 experience will soon teach one which branches are likely to 

 prove prolific. As a general rule one may say that old-looking, 

 I but still sound and green, branches will be the best. The water 

 Milfoil {Mi/riopht/lluiii) is one of the best of water plants to 

 examine and collect, on account of the ease with which its 

 leaves can subsequently be placed under the microscope. 

 Anacharis is more troublesome, but it is occasionally found 

 covered with Pond-life, and is an excellent weed for the 

 aeration of aquaria. 



The rootlets of reeds and of trees growing near the edge of 

 the water should be examined for Sponges and Polyzoa, such as 

 Lojilioptt!', PhiiiiiileUn, Fretlericella, etc. In order to obtain 

 some weeds growing near the middle of a pond or lake, a loaded 

 three-pronged hook, attached to a hue, may be used ; this is 

 swung round, and may be thrown to a distance of 20 to 

 2.') yards, where it sinks, and the weeds that are caught by the 

 hooks are dragged on shore. 



By these various means a good collection of pond organisms 

 can readily be made after a little practice. Though the spring 

 and autumn are perhaps the best season for collecting. Pond-life 

 is never absent, even in the winter under the ice. 



Having thus filled some bottles with condensed water from 

 various ponds, and placed some promising branches of water 

 plants in another bottle filled with uncoudensed and clean pond 

 water, the bag is taken home. It is a great mistake, however, 

 to overstock the bottles with weeds, as the plants in such 

 crowded bottles may begin to decompose, killing most of the 

 animals in a short time. 



On reaching home, the first thing to do is to empty the 

 collecting bottle into larger vessels or small aquaria in such a 

 way that the captures may be more critically examined, isolated, 

 and, if found desirable, placed under the microscope. 



By far the best and most convenient way of doing this is to 

 transfer the contents of each bottle into a small window 

 aquarium, filling it up with tap water. The weeds and rootlets 

 that have been brought home are put in another window 

 aquarium in clean pond water. 



These small window aquaria, with flat and parallel sides 6 to 

 8 inches long by 5 to 6 inches high and only \^ inches wide 

 inside, are the best nurseries for the microscope. The difficulty 

 of seeing and capturing small objects in a large or ordinary 

 round aquarium is very great, and the use of the pocket lens 

 almost hopeless, whilst in these flat and narrow aquaria no 

 object is out of reach of the lens, and the whole contents can be 

 looked over without difficulty and in a very short time. 



By placing the tank on a what-not at a convenient height 

 before a window, or before a lamp at night, most of the free- 

 swimming Rotifers will collect against the glass nearest to the 

 light, where they can be examined with the greatest ease and 

 picked up with the pipette if desired. A disk of black card- 

 board placed some little distance behind, produces a very good 

 dark ground, against which the smallest visible specks stand out 

 well. 



The condensed pond water is, of course, frequently so dirty 

 with floating particles 'of dSrin, that it is at first hardly 

 possible to see through it; but after standing half-an-hour it 

 will be found that most non-living particles will have fallen to 

 the bottom, and after several hours the water will be quite 

 clear and every living creature will be readily seen. 



During the summer months, when Daphnia and Cyclops are 

 abundant, the net frequentlj' collects these in such numbers 

 that they become a nuisance. In order to separate them, when 

 such is the case, I have adopted the plan of passing the water 

 through a small sieve made of material with meshes sufficiently 

 wide to allow the largest Rotifers and Infusoria to go through, 

 whilst keeping back most of the Cyclops and Water-fleas ; the 

 latter are then transferred to a separate tank to be examined by 

 themselves. 



It is very desirable to examine the collected objects as soon 

 as convenient, the same day if at all possible, and not later than 

 the day after their capture, as many organisms soon die and 

 disappear under the crowded and unnatural conditions in which 

 they are kept in c.iptivity. Rotifers can often, particularly in 



