3i8 THE PHYSIOLOGY OF REPRODUCTION 



femients present in the ovaries and testes of toads, frogs, and newts. 

 The watery extracts of these organs had the power of decomposing 

 hydrogen peroxide with the formation of water and oxygen, and of 

 oxidising guaiaconic acid to guaiacnm bhie, so that a blue colour 

 appeared when these extracts were added to an emulsion of guaiac 

 resin. These reactions indicate the presence of a catalase and of a 

 peroxidase in the extracts of the sexual glands. Such ferments are 

 present m many, if not all, organs and tissue fluids, but a special 

 significance is attributed by Ostwald to their presence in the ova 

 and spermatozoa, because he found the spermatozoa to contain 

 more catalase and more peroxidase than the ova, and because 

 the activity of these ferments — especially the peroxidase — is 

 increased when the extracts of ova are mixed with the extracts 

 of spermatozoa. 



The development of the ovum after fertilisation is, according to 

 Ostwald, due to this activation of the oxidising ferments inducing a 

 chemical synthesis of nuclein substances and leading to the formation 

 of the astrosphere. According to the view of Fischer and Ostwald,i 

 which is, however, not accepted by other workers,^ the formation of 

 the astrosphere initiates cell-division, and therefore the development 

 of the egg. 



The investigations on artificial parthenogenesis show that it is 

 possible to replace the developmental function of the spermatozoon 

 by physico-chemical means. But the spermatozoon has also the 

 hereditary function of transmitting the paternal characters to the 

 developing embryo by fusing its nuclear material with that of 

 the ovum. One must distinguish, therefore, clearly between these 

 two functions of the spermatozoon. There is evidence that these 

 two functions depend upon different materials in the spermatozoon 

 and that even when an ovum is fertilised by a spermatozoon only 

 one of these two functions may operate, namely the developmental 

 one, while the hereditary function remains inoperative. Loeb 

 succeeded in inducing experimental hybridisation between two widely, 

 different species, the egg of a sea-urchin and the sperm of a starfish, 

 by placing them in shghtly alkaline sea-water. The plutei which 

 developed were in every point identical with the pure breed of the 

 sea-urchin (Strongylocentrotus purpuratus). Other workers have 

 obtained similar results in other animals. A very striking case is 

 that observed by Hertwig and based on the fact that exposure of 

 spermatozoa to radium damages them. The damage can be graded 

 in such a way that the spermatozoon can still enter the egg, but its 



1 Fischer and Ostwald, "Zur Physikalisch-Chemisehen Theorie der Be- 

 iracht\mg,'ljyiuger's Arch., vol. ovi., 1905. 

 ^ See, for instance, Burrian, loc. eit. 



