HA RD WICKE' S S CIENCE- G SSI P. 



231 



was estimated at 2,000,000 dollars, and in that of 

 Minnesota, at 3,000,000 dollars, a damage of over 

 1,000,000/. sterling. 



There are other insects' eggs which are dreaded by 

 the agriculturist, among which are those of the 

 Hessian fly ( Cecidoinya destructor), which attacks the 

 stalk of wheat. The fly breeds twice a year. The 

 first brood of eggs, which are very small reddish 

 grains, are deposited in the upper channel of the 

 wheat leaf, soon after the stalk begins to bud out. 

 They are hatched in about fifteen days. 



The grain- weevil (Calandra granatis) attacks the 

 grain at the time of ripening, and continues its 

 ravages long after it is harvested. A single pair, it 

 has been asserted, will multiply to five or six thousand 

 during one year. The wheat-midge {Cecidomys tritici) 

 is another ravager, which lays its eggs on the blossoms 

 and soft immature grain, and the eggs hatch in six or 

 eight days. 



The eggs of moths are laid on the young shoots 

 or on the bark of the plant on which the caterpillar 

 has to feed, and the way in which they are -laid is 

 often very strange. The common lacquey moth (C. 

 Neustria) makes a ring or bracelet round the twigs of 

 the hawthorn, covering the eggs with a kind of 

 cement, which is an effectual covering. 



The egg of a moth or butterfly is found of various 

 shapes, sizes, and colours (some being ribbed or 

 smooth, others hemispherical or spherical, and others 

 cylindrical) and of a green, brown, or dusky white 

 colour. A study of these eggs under the microscope 

 is well worth the trouble of procuring them. They 

 possess extraordinary vitality, neither baking nor 

 freezing producing any other effect than making the 

 exclusion of the caterpillar earlier or later. 



The night-butterfly often devastates the Prussian 

 and Polish forests, eating down acres of pine-trees, 

 leaving the trunks perfectly bare. The eggs cover 

 them as a layer. Some years ago, in the course of 

 a few months, 300 lbs. of their eggs were collected 

 in one district only, equal to about 150 million 

 insects. 



If we turn to flies, millions of eggs are laid by 

 them, whence proceed in a day or two innumerable 

 devourers of dead flesh. The common house fly 

 (Musca domesticd) lays from 120 to 150 eggs ; M. 

 Ctzsar and Sarcophaga camarria are equally prolific ; 

 and after a -few days, when perfect flies, these in 

 theiri turn lay about 150 eggs, which in two weeks 

 become flies again, and so on. It is no wonder, 

 therefore, their numbers increase so rapidly. 



The eggs of dozens of other predatory insects 

 have to be kept under by birds or the devices of 

 man. 



The eggs of the walking-stick insect (Eurycantha 

 horrida) a native of New Guinea, are said to be as 

 large as those of the small humming-bird. This 

 insect was figured in Science-Gossip for March, 

 1875. 



NOTES ON THE INFUSORIA. 



By Bernard Thomas. 



VII. 



BESIDES the single varieties of the Vorticellina:, 

 there are others on branching stalks that live 

 in colonies. Among these may be mentioned Epi- 

 stylis, Zoothamnium, and Carchesium. In the first 

 the stalk is not contractile ; in the second the stalk 

 is contractile, but not the main stem, while in 

 Zoothamnium the whole tree is contractile. 



33. Zoothamnium spirale (Fig. 141, A, B, C) is a 

 marine species sometimes found with Polyza. It is 

 an exceedingly beautiful form. It may be compared 

 to a branching tree with little bell-like organisms in- 

 stead of leaves. Some of the bells are small ; others, 

 of much larger size, are arranged in the axils of the 

 branches. When the protoplasmic thread contracts, 

 the whole tree bunches up and the stem is lost among 

 the bells crowded closely together. Then the stem 

 slowly expands again, somewhat spirally, and the 

 bells gradually open and their cilia begin to play. 

 The individual bells closely resemble Vorticella, but 

 the nucleus is round and not a bent rod. A delicate 

 protoplasmic thread may be seen traversing the stalk 

 and branching with it. In Goss's " Tenby " there 

 is a beautiful illustration of this species, and the 

 following short description : " Zoothamnium spirale : 

 pedicle slender, spirally bent ; branches short, neither 

 umbellate nor vorticellate, but set spirally on the 

 trunk ; bells sessile, spirally arranged, with a terminal 

 one ; large bells few, axillary. Inhabits sea-water." 

 Besides Z. spirale there are other species, as Z. 

 arbuscula, which is described as racemose, umbellate, 

 the branches all coming from the top of the stem. 

 It inhabits fresh-water. 



34. Epistylis nutans (Fig. 141, d). The bell 

 resembles somewhat that of Vorticella. The oeso- 

 phagus is ciliated. Where the bell joins the stalk the 

 cuticle is jointed, and this permits a nodding move- 

 ment of the bell. Carchesium is another branched 

 Vorticella. It is a very beautiful form and inhabits 

 fresh-water. 



35. Trichodina pediculus (Fig. 144, A, B) has no 

 stalk and lives attached by a sucker-like base to 

 some other organism. I have studied the morphology 

 of this little infusorian, which I found in large numbers 

 on a black Planarian. The Planarian can easily be 

 procured for examination. It is a black, slug-like 

 animal about one-eighth of an inch long, which crawls 

 about the bed of the pond. As I have made the 

 little infusorian the subject of a former paper, I will 

 only briefly describe the morphology. The under- 

 surface is concave with circular outline. In the centre 

 there is a hole and round this a ring of protoplasm. 

 Outside this ring are short radiating bars. This is 

 the " muscular " apparatus hy means of which Tricho- 

 dina attaches or detaches itself. Surrounding the base 



