3i6 THE PHYSIOLOGY OF REPRODUCTION 



conditions governing fertilisation by a spermatozoon, then it follows 

 that a spermatozoon should contain two substances, namely, a 

 cytolysin and a substance inhibiting the initial cytolysis. The 

 presence in the spermatozoon of a cytolysin ■ can indeed be proved. 

 Extracts of the testis of a cock, or the dead semen (killed by heating) 

 of a starfish or a mollusc, will induce the initial process of cytolysis 

 in the eggs of a sea-urchin. The dead semen of a sea-urchin, 

 however, is quite inactive against the eggs of a sea-urchin. The 

 observations of Pieri,^ of Dubois,^ and of Winkler,* who claimed to 

 have extracted from the spermatozoa of various invertebrates ferments 

 which induced segmentation of the mature ovum of the same 

 species, were proved to be due to fallacies by Gies * and by Cremer.* 

 The fact is, as Loeb showed, that the extracts must be prepared from 

 the spermatozoa belonging to a foreign species. This apparently 

 paradoxical phenomenon is in agreement with our knowledge of 

 the actions of cytolysins generally. The cytolysins present normally 

 in the serum or the cells of one animal are always inactive against 

 the cells of animals of the same species, and act only against cells of 

 animals of a different species. The explanation of this fact is to be 

 found, according to Loeb, in the diminished permeability of the cells 

 of one species towards the cytolysins produced by the cells of animals 

 of the same species, the so-called auto-cytolysins. 



Similarly the ovum of an animal is not permeable to the 

 cytolysins contained in the spermatozoon of an animal of the same 

 species. In order to bring about the development of the mature 

 ovum the auto-cytolysin must be carried bodily into the egg. And 

 that is the function of the motile spermatozoon. 



This bold conception has received a striking though unintentional 

 confirmation by theobservations of Bataillon. He succeeded in 1910 in 

 inducing parthenogenesis in frogs' eggs by simply pricking them with 

 a needle, provided, as he found afterwards, that the needle carried 

 with it a trace of the blood. He believes that it is the leucocytes 

 which are introduced by the needle which cause the development. 

 A few years previously Guyer in 1907 had obtained similar positive 

 results by injecting frogs' eggs with the lymph or the blood from 

 another frog. 



' Fieri, "Un nouveau Ferment soluble: I'Ovulase,'' Archives de Zoologie 

 Experimentale et GeTierale, vol. xxix., 1899. 



^ Dubois, " Sur la Spermase et I'Ovulase," Gomptes Rendus de la Soe. de 

 Biol., vol lii., 1900. ^ 



2 Winkler (H.), "tjber die Furchung unbefruchteter Eier unter der 

 Einwirkung von Extraktivstoffen a. d. Spermata," Nachrichten der kgl. Gesell- 

 gckaft der WisseTischaften zu Oottingeji, Mathemat.-Phys. Klasse, 1900. 



^ Gies, " Do Spermatozoa contain an Enzyme having the Power of Causing 

 Development of Mature Ova?" Amer. Jomr. of Physiol., vol. vi., 1901. 



^ Quoted from Loeb, Dynamics of Living Matter. 



