A REEXAMINATION OF THE CYTOLOGY OF 

 HYDRACTIXIA AND PENNARIA. 1 



W. M. SMALLWOOD. 



The present report does not claim to be a complete discussion 

 of the cytological phenomena in the developmental history of 

 Hydractinia and Pennaria, nevertheless, it adds considerable new 

 data hitherto unpublished concerning the problem of the structure 

 of the egg, the migration of the chromatin, maturation, fertiliza- 

 tion and mitosis. However, the present paper cannot claim to 

 settle the controversy as to the existence of amitosis because the 

 results concerning which there may be some differences of opinion 

 have been negatively interpreted. 



During the summer of 1906 Professor C. W. Hargitt asked me 

 to undertake a reexamination of some of his work on hydroids 

 paying particular attention to the cytological phenomena of the 

 early development, that being the point of most interest. The 

 results of Bunting, '94, on Hydractinia were not in agreement 

 with his observations on Pennaria, Eiidendriwn, Clara, etc., so 

 that he suggested that it might be well to restudy this form also. 

 While I have had opportunity to examine all of Professor Har- 

 gitt's preparations on the several hydroids studied by him, it 

 seems wise to confine this paper to Hydractinia and Pennaria. 



It is not often that such a study as this is undertaken and when 

 it is there is involved a great deal of work that it would be super- 

 fluous to republish so that the present paper needs to be read in 

 connection with Bunting, '94, on Hydractinia and Hargitt, '04, 

 on Pennaria. At the beginning of this study, Professor Hargitt 

 explicitly stated that he wished to give me absolute freedom in 

 the problem and the interpretation of the results. This he has 

 done even to the extent of not seeing any of my preparations 

 until I turned over the finished paper to him. 



When he asked me to undertake this restudy, he volunteered 

 to collect and preserve the material necessary. In this particular 



1 Contributions from the Zoological Laboratory, Syracuse University, C. W. Har- 

 gitt, director. 



209 



