356 DR 1). BEKRY HART. 



as is necessary, in the development of the organs, but still 

 ancestral. 



The view I would advance is as follows : The development of 

 the ovary and testis is one intimately bound up with that of the 

 mesonephros. The mesonephros may, indeed, be considered as a 

 sexual excretory organ. In the Amniota the development of 

 the sexual organs is completed early in footal life, and the after 

 function of the ovary or testis is to provide a comparatively 

 small number of ova or spermatozoa at long intervals, in mammals 

 at any rate. 



In the Anamnia, however, the ovaries and testes produce a very 

 large number of their characteristic products, and thus the great 

 local activity of these organs leads to a retention of the meso- 

 nephros as an excretory organ in close vascular relations with 

 the sexual organs. 



The persistence of excessive ovarian and testicular activity in 

 the Anamnia is to be associated with the persistence of the meso- 

 nephros. 



On this point Noel Paten's researches on the Salmon are of 

 value, and the following quotations put the matter briefly : — 

 " Yearly, or at longer intervals, the fish appear on our coasts, 

 apparently from the deeper waters, and ascend the rivers there 

 somewhere between October and January to deposit their spawn 

 milt. Having done so, they descend the river as kelts and again 

 disappear in the sea, to return either in the same or in the 

 following year to the fresh water. 



" What force urges the fish to leave its rich feeding ground in 

 the sea ? Is it necessary that it should enter fresh water in 

 order to perform the act of reproduction ? Does it require or 

 procure any food during its sojourn in tlie river ; and if not, how 

 is it able to maintain life and to construct its rapidly growing 

 genital organs ? In the female the growth of these is enormous. 

 In April or May the ovaries constitute only about 1*2 per cent. 

 of the weight of the fish. In November they are no less than 

 23*3 per cent. In a fish of thirty pounds, in the spring they 

 weigh about 120 grammes, in November they weigh over 2000 

 grannnes. The increase in the testes in the male is not so 

 marked, but is sufficiently striking. In April or May their 

 organs are about 0"15 per cent, of the weight of the fish, while in 

 November they are 3-3 per cent." 



I 



