No. 6.] AMERICAN MORPHOLOGICAL SOCIETY. 347 



In addition to observations upon the changes in the sec- 

 ondary sexual characteristics induced by castration, the effect 

 of absorption of testicular material through the peritoneum 

 was the end in view. 



Upon castration the testes of the cockerel were returned 

 free into the abdominal cavity. After six weeks a living ripe 

 testis, one inch long, was introduced into the abdominal 

 cavity through an incision anterior to the last pair of ribs. 

 The experiment was conducted on a scale too small to abso- 

 lutely determine how far the results were due to direct regen- 

 eration of the testes, and how far to absorption of the 

 introduced testicular material. Two points, however, were 

 demonstrated: (i) that the testes do regenerate; (2) that the 

 introduced testicular material was absorbed. In one case it 

 seemed clear that the secondary sexual characteristics devel- 

 oped solely as the effect of the absorption of the introduced 

 testicular material, without regeneration of the testes. In 

 another individual similar conditions were strongly indicated, 

 but were obscured by a pathological growth. 



XV. THE MORPHOLOGICAL PHENOMENA IN- 

 VOLVED IN THE CHEMICAL PRODUCTION 

 OF PARTHENOGENESIS IN SEA URCHINS. 



EDMUND B. WILSON. 



IN accordance with Loeb's important discoveries on Arbacia, 

 unfertilized eggs of Toxopnettstes, when treated by the mag- 

 nesium chloride method, may segment and give rise to free- 

 swimming blastulas, gastrulas, and Plutei. There is always a 

 considerable proportion of abortive and monstrous forms, and 

 none of the stages are exactly like those arising from fertilized 

 eggs, though often closely similar to them. The Plutei pos- 

 sess, however, the characteristic arms, pigment, skeleton, and 

 divisions of the gut. That these eggs have not been acci- 

 dentally fertilized is proved by the fact, demonstrated to the 

 society by an exhibition of sections, that during cleavage they 



