III. 8 CHEMICAL COMPOSITION 129 



Hertwigs argue that the contractility of the cytoplasm is 

 impaired in these solutions. Chloroform dissolved in sea-water 

 has the very interesting property of stimulating without 

 the addition of spermatozoa the formation and separation of 

 the vitelline membrane. The male generative cells are also 

 sensitive to the action of these alkaloids, but not necessarily in 

 the same measure. They can resist, for example, the influence 

 of a solution of nicotine, which is ten times as strong as one 

 necessary to evoke pathological changes in the ova. Though 

 chloral hydrate (0-5 %) and quinine (0-05 %) are both temporarily 

 fatal to the motility of the spermatozoa, sea- water restores the 

 capacity for fertilization. Strychnine (0-01 %) and morphine 

 (0-5 %) are without effect. 



In the experiments just described the abnormalities seem to 

 be directly due to the initial paralysis of the egg by the reagent 

 and consequent polyspermy. 



Should, however, the egg have been first normally fertilized, 

 the irregularities produced by the subsequent action of the poison 

 are, though well marked, not of the same kind, for in this case 

 the vitelline membrane has already been formed and only one 

 spermatozoon has gained admittance. Chloral hydrate (Fig. 68, 

 k-p) was employed for ten minutes and at varying intervals after 

 insemination (one, one and a half, five and fifteen minutes). 

 Exposure to the solution very shortly after insemination first 

 retards the progress of the sperm-head and the formation of its 

 aster, and when later on the chromosomes are formed they lie 

 heaped together in the centre of an achromatic figure described 

 as a pseudo-tri- or pseudo-tetraster. This consists of three or 

 four conical groups of fibres, the bases resting on, and the fibres 

 connected to, the chromosomes, the apices outwardly directed 

 and sometimes with, sometimes without, asters ; in any case, 

 however, they are not united by spindles, as is the case in 

 the complex figures observed in polyspermy. Isolated asters 

 are also to be seen in the cytoplasm, and, which is perhaps 

 more remarkable, the female chromosomes are themselves the 

 centre of a unipolar (fan-shaped) or multipolar apparatus of 

 the same kind. The reader will not fail to notice the similarity 

 to the phenomena occurring in artificial parthenogenesis. 



