STLIDIKS IN 'J'HK EXl'Ki; IM KNTAL ANALYSIS OF SKX. 225 



Studies in the Experimental Analysis of Sex. 



By 



OeoflVey Siniili, 



Fellow of New Colleo-e, Oxford. 



With Plate 14. 



3. FuKTHER Observations on Parasitic Castration. 



During my occupation of the British Association Table at 

 Naples this winter I took the opportunity of re-examining 

 certain points connected with the effect of Sacculina 

 neglecta on the spider-crab Inachus niauretanicus, 

 with the especial purpose of trying to settle the exact way 

 in which the gonad of infected individuals degenerates and 

 is absorbed. The mid-winter months being the most favour- 

 able season at Naples for finding numerous individuals of 

 Inachus very profoundly modified by the presence of the 

 parasite^ I was able to re-investigate many crucial stages in 

 the modification of the external and internal sexual organs, 

 with the result that, while certain new facts of interest have 

 come to light, I see no reason whatever for departing in any 

 respect from the statement of facts made in my earlier work, 

 or from the deductions drawn from them (' Naples Mono- 

 graph,' No. 29, Chap. Y). In this paper, besides giving the 

 results arrived at in respect to the degeneration of the gonad, 

 I propose to describe certain new instances of infected 

 Inachus which afford incontestable proof that male crabs 

 with differentiated though reduced male internal organs can 

 assume all the adult female secondary sexual characters. 

 It will also be shown both for the male and female sex that 

 the effect of parasitic castration can on no account be 



