rNVERTEBRATAj CRYPTOGAMU, MICROSCOPY, ETC. 599 



usually recognisable at once. Animaloula were not found in an 

 active state in water from ice that just melted, but upon allowing 

 such water to settle and become warm at the ordinary temperature of 

 a room occupied for living purposes, the sediment deposited is found 

 to contain, after some hours, monads whose movements are easily 

 discernible with a magnifying power of from 200 to 400 diameters. 

 Upon allowing the water to stand still longer, Mr. Veeder found the 

 Confervae growing thriftily, and in some instances forming clusters 

 or bundles frequented by minute animalcula, the entire ajipear- 

 ance in this case being very similar to that presented by the nests 

 occupied by the young of the common Paramecium seen in stagnant 

 water. 



As the result of these investigations, it appears that freezing does 

 not free water from filth due to the presence of sewage or decaying 

 vegetable matter, and further, that it is probable that the germs from 

 which animalcula are developed, if not the animalcula themselves in 

 a quiescent state, are present in very much of the ice fciken from 

 stagnant water, so that the use of such ice in drinking water is 

 hazardous to say the least. 



B. INVERTEBRATA. 



Fertilization of the Ovum.* — Professor Schneider calls attention 

 to his observation in 1873, on Mesostomum and Disfomum, tliat 

 the nucleus and germinal vesicle become elongated and break up 

 into strands, which ultimately become arranged into a rosette, under- 

 going further changes. The grouping of the granules of the proto- 

 plasm of the cell into a star-shaped form was described in 1847, by 

 Derbes in the sea-urchin's egg, and by Eeichert in the sj)erm-cells of 

 Nematodes, &c., and similar facts by Kowalevsky in 1866. Biitschli's 

 observations on the " directive vesicles " are not beyond criticism. 

 These are really cells, and consist of part of the germinal vesicle 

 with some protoplasm. 



Professor Schneider's own recent observations,! carried out on 

 Nematodes, Hirudinea), and Asteracantldon ruhens, show that the sperm- 

 nucleus has no existence. lie agrees with Fol with regard to Astera- 

 cantldon in the main. A very small portion of the germinal vesicle 

 is extruded with the directive vesicle ; the rest sends out ameboid pro- 

 cesses in all directions, wliicli are, however, very ditlicult to demon- 

 strate. The tliickncss of the ovum often gives very misleading views 

 of these relations. This ditfusion of the substance of the nucleus in 

 the ovum renders it almost impossible for tlio entering siKrniatozoou 

 to miss it. The stellate mass described as surrounding the latter at 

 its entrance probably belongs to the germinal vesicle, attracted by tho 

 stimulus of tho male clemenl. At the cleavage the two stellate masses 

 of the amjjJiiastcr go to diflercnt parts, and then both approach tho 



♦ ' Zool. Anzcig.,' iii. (1880) p. 2r)2. 



t He observes tliat lie liaa loniul acetate of cnruiino (mudo by saturating 

 boiling acetic acid of 45 per cent, strength with carmine, and fiUoring) very iiscfnl. 

 It isuHed either diluted to a 1 per cent, solution or by placin;,' a drop of the ori^iu.d 

 boluliou uuilcr the cover-;^labd. 



