240 (IKOl'KREY SMITH. 



consists, firstly, in establishing a bacterial disease of a verte- 

 brate as a cause of parasitic castration and thus extendinor 

 the operation of this principle to two new classes of organisms, 

 and secondly, in bringing out the correlation between the 

 activity of tlie testes and the development of the comb and 

 wattles of (lallus bankiva. In the next part this correlation 

 will be dealt Avith more fully on an experimental basis. 



Lettering. 

 C. S. Connective tissue sheath. En. Endopodite. Ex. Exopodite. 

 N. Germinal nuclei. 0. Ovary. T. Testis. V. S. Vesicula seminalis. 



EXPLANATION OF PLATE 14, 



Illustrating j\Ir. (ieoftrey Smith's paper on " Studies in the 

 Experimental Analysis of Sex." 



All the figures refer to Inuclius mauretauicus (Lucas). 



Yv^. 1.— First abdominal appendage (copulatory style) of noi-mal 

 uninfected male. X 5. 



Fig. 2. — Second abdominal appendage of normal uninfected male, x 5. 

 . Fig. 3. — First abdominal appendage of infected male " A." X 5. 



Fig. 4. — Second abdominal appendage of infected male '• A." X .5. 

 (This figure might sev\e equally well for the abdominal appendage of 

 an adult female.) 



Fig. 5. — Second abdominal appendage of infected nuile " B." x 5. 



Fig. 6. — First abdominal appendage of infected male " B." x 5. 



Fig. 7.— Second abdominal appendage of nonnal uninfected female» 

 before adult condition is assumed. X o. (The adult form of this 

 appendage is practically identical with that given in fig. 4.) 



Yia;. 8.— Vesicula seminalis of a small normal male, measuring 14 mm. 

 carapace length. X 20. 



Fio-. 9.— Coils of testis of the same male. X 20. 



■pi(f, 10. — Yesicula seminalis. duct, and coils of testis of infected 

 male"" A." X 20. 



YW. 11.— Portion of testis of an infected male, showing absorption 

 of germinal cells in connective-tissue sheath, x 30. 



Y\o-. 12. Portion of ovary of an infected female, showing alssoi-ption 



of ova and germinal cells in connective-tissue sheath. X 30. 



p;,^. 13.— Another portion, higher magnification, of ovaiy of infected 

 female. X 60. 



