STUDIES IN THE EXPERIMENTAL ANALYSIS OF SEX. 233 



Let us examine what the process of becoming adnlt involves 

 in an ordinary female crab. Plainly the most important 

 change is the rapid elaboration of yolk material which accu- 

 mulates in the ovary, causing the latter to grow to a very great 

 size. This elaboration of food material in the ovary is the 

 fundamental point in which the adolescence of the female 

 gonad differs from that of the male. In the male gonad at 

 maturity we have an immense multiplication of nuclei and of 

 chromatin but a small development of cytoplasmic material 

 and no deposit of yolk ; in the female we have the exact 

 opposite of this process. The most important part, then, in 

 the process of becoming adult female, is the active elaboration 

 of yolk material. 



We have arrived, therefore, at this point of the argument: 

 that the presence of Sacculina causes the crab of either sex 

 to become adult female in nature, and the most important 

 activity of this state is the elalioration of yolk material. Can 

 we prove that the presence of Sacculina actually causes its 

 host of either sex to produce yolk material ? I believe we can. 

 If the roots of Sacculina which fill the body of an infected 

 Inachus be examined, they will be found to be packed with 

 small globules of an oily material, and if the roots are stained 

 with such a mixture as Ehi-lich-Biondi's tri-acid stain it may 

 be observed that the Sacculina roots take up the same consti- 

 tuent in the stain, namely the acid fuchsin, as the yolk of 

 an adult female crab's ovaries. From the observed contents 

 Qf the Sacculina roots find from their reaction to stains it is 

 clear that the}' are elaborating from the blood of the Inachus 

 of both sexes a closely similar yelk material to that which is 

 xiormally accumulated in the ovary of a healthy adult female 

 Inachus. 



The effect of Sacculina on Inachus is therefore to force 

 the latter to elaborate yolk material of a similar kind to that 

 which is normally developed in the ovary of the female at 

 maturity. As the Inachus elaborates it the Sacculina 

 abstracts it, so that it does not come to be deposited in the 

 gonad until after recovery from the disease, when, as we have 



