BIOCHEMISTRY OF THE SEXUAL ORGANS 291 



substance containing phosphorus and iron was isolated from the 

 eggs of the salmon by Noel Paton, from cods' eggs by Levene, and 

 from perches' eggs by Hammarsten. 1 The statement by Walther 

 that ichthulin, on boiling with mineral acids, splits off a reducing 

 sugar and differs in this respect from vitellin has not been confirmed 

 by the later workers. 



A protein, clupeovin, which differs in many respects from these 

 ichthulins has been isolated from the eggs of herrings by Hugounenq, 2 

 and Galimard has obtained a similar substance from the eggs of 

 frogs which he calls ranovin. Most authorities, however, doubt the 

 chemical individuality of these proteins. 



Ichthulin is probably identical with the crystalline material 

 observed in the eggs of the tortoise, the frog, the shark, and other 

 fishes, which is known morphologically under the name of yolk- 

 spherules or " Dotterplattchen." The unripe eggs of the perch are 

 embedded in a fluid from which a protein of the nature of a globulin 

 has been isolated. This protein received the name " percaglobulin." 3 

 It is rich in sulphur, and is precipitated by weak hydrochloric acid. 

 It has an astringent taste, and possesses the remarkable property of 

 forming precipitates with some glucoproteins such as ovomucoid, and 

 with polysaccharides such as glycogen and starch. This substance 

 could not be found when the eggs were mature, and does not appear 

 to be present in the ovaries of other fishes. 



Very important and interesting results have been obtained by 

 systematic chemical examinations of the muscles and ovaries of the 

 salmon 4 and of the herring 5 at different seasons. Extensive chemical 

 changes take place in these animals during the period of their 

 reproductive activity. The reproductive organs develop at the 

 expense of the muscles, which dimmish in weight. This is best 

 seen in the salmon, since this animal does not take any nourishment 

 during its passage up the rivers. In the herring the conditions are 

 not quite so simple, because the herring feeds until spawning occurs, 

 although less food is taken in the later months. 



In the case of the salmon, then, the ovaries are built up from 

 material contained in the muscle. The most marked change in the 



1 Hammarsten, "Chemie des Fischeies," Skandin. Arch. f. Physiol., vol. xvii., 

 1905. This paper contains a detailed review of previous work done on this 

 subject. 



2 Hugounenq, "Sur une albumine extraite des oaufs des poissons," Compt. 

 Rend., vol. cxxxviii., 1904. Galimard, ibid. 



3 Morner, " Percaglobulin ein charakteristischer Eiweisskorper aus dem 

 Ovarium des Barsches," Zeitsch. f. physiol. Chem., vol. xl. 



4 Miescher, Histochemische und physiologische Arbeiten. Noel Paton and 

 others, " Report of Investigations on the Life-History of the Salmon in Fresh 

 Water," Report to the Fishery Board for Scotland, 1898. 



5 Milroy, "Changes in the Chemical Composition of the Herring during 

 the Reproductive Period," Biochem. Jour., vol. iii., 1908, p. 366. 



