GERM-CELL HISTORY IN THE BROOK LAMPREY 113 



influencing the germ cells in different parts of the gonad. Thus 

 we may have, in the same gonad, certain cells with high oxidizing 

 capacity which continue to divide and form cell nests, and other 

 cells, with a high storage capacity, which enter the growth period 

 very early and become oocytes. After the larva has become 

 decidedly male or female in character, as evidenced by the pro- 

 portion of cell nests and oocytes, it appears that the opposite 

 sex tendency is in decline. This can be attributed to the pres- 

 ence of sex-differentiating enzymes produced by the predominat- 

 ing sex character. This results in the arrest of the development 

 of the opposite sex character and often in its degeneracy. 



Goldschmidt has worked out a theory of enzyme action in 

 connection with sex which seems to be in the right direction. 

 He assumes that ''in the fertilized egg the enzymes which govern 

 the differentiation of the organism towards one of the two alter- 

 natives, maleness and f emaleness, are both present." These hypo- 

 thetical enzymes he speaks of as andrase and gynase. The dis- 

 tribution of the sex chromosome "results in the formation of two 

 kinds of fertihzed ova, differing in the relative concentration of 

 the two enzymes." Since in "mixtures of different enzymes, 

 every single one reacts independently, providing no interfering 

 reaction product is formed," a decision must be reached during 

 differentiation of the organs as to whether they shall develop along 

 the male or the female line. "This decision must be brought 

 about by the action of the dominating enzyme." The more 

 nearly the two enzymes approach each other in strength, the 

 earlier do they show their double influence on the developing or- 

 ganism. Such seems to be the case in the intersexual moths which 

 show all degrees of intersexuality, from slight changes in the sec- 

 ondary sexual characters, which are latest to be formed, to changes 

 in the germ gland itself, which is the first sex organ to differenti- 

 ate. The same idea may be applied to the lamprey, where various 

 grades of intersexuahty are found in the germ gland, and where 

 the sex differentiating factor seems to operate early in some of 

 the larvae and later in others. 



We are not, strictly speaking, concerned in the present work 

 with the causes which underlie the development of the secondary 



