OF MIOni'S.K MADE BY WILLIAM KK1TH BROOKS. 5 



west coast of Greenland, and we have found it in great abundance in Narragansett and 

 Buzzard's Bays, on the southern coast of New England. It has not been taken at Beaufort, 

 North Carolina, nor at any station farther south. The medusae are very common in Narra- 

 gansett Bay from the middle of June until October, and I enjoyed exceptional opportunities 



Fie. 74. Podocoryne carnca, hydroid and young medusa. Drawn from life by Professor William K. Brooks, 

 and kindly presented to the author for publication in this work. 



for observing their growth and development while studying at Dr. Alexander Agassiz's labo- 

 ratory at Newport, in 1892-96. 



In 1881-82 de Varenne concluded that both eggs and sperm-cells originate in the entoderm 

 of the coenosarc of the hydroid and afterwards migrate into the medusa-bud. The more 

 careful researches of Weismann, 1883, however, refuted this view, showing that the male 

 germ-cells originate in the ectoderm ot the budding medusa, but do not wander from their 

 place of origin. On the other hand, the female germ-cells may possibly originate in the ecto- 

 derm; if so they soon wander into the entoderm of the budding gonophore, then into the spadix 

 of the medusa-bud and finally into the ectoderm of the manubrium of the medusa. According 

 to the later studies of Ishikawa and ot Bunting, however, the egg-cells originate in the ento- 

 derm of the medusa-bud and afterwards migrate into the ectoderm. 



