No. 2.] THE ORIGIN OF THE SEX-CELLS. 207 
note by Varenne in 1882, in which he gave a short account of 
the development of the embryo and the origin of the sex-cells. 
In 1883, Weismann, in his work on the origin of the sex-cells 
in the Hydromedusae, gave a description of the origin of the sex- 
cells and development of this medusa, while in 1888, Ischikawa 
published a paper upon the female sex-cells of Podocoryne. 
MATERIAL AND METHODS. 
The material was obtained while studying at the Marine 
Laboratory of Wood’s Holl, Mass., during the summers of 
’91 and’g2. The shells, containing upon them both the Podo- 
coryne and the Hydractinia, were found at low tide off Naushon 
and the Buzzards Bay side of the peninsula of Wood’s Holl ; 
while the Hydractinia was also obtained in great abundance 
at Wood’s Holl upon the Vineyard Sound. 
The surface views and segmentation were at first studied 
under the direction of Professors C. O. Whitman and J. Playfair 
MacMurrich during the summer of ’9i1; to whom I extend my 
thanks for timely suggestions. The work was continued and 
completed under the supervision of Professor T. H. Morgan, for 
whose interest and willing assistance, I am very grateful. 
The killing reagents, which have been found most successful 
out of the many experimented with, are “ Kleinenberg’s Picro- 
sulphuric”’ in salt water, and Alcoholic Corrosive Sublimate. 
Both are equally good as to their preserving qualities, but the 
latter is much better, in that the staining process is more 
easily carried out after its use. The stains that brought out 
the cell structure in the clearest manner were Mayer’s Picro- 
carmine and Kleinenberg’s Haemotoxylin. 
FORMATION OF THE GONOPHORE IN HYDRACTINIA, WITH THE 
ORIGIN OF THE SEX-CELLS. 
The male and female sexual hydroids of Hydractinia, known 
as the blastostyles, arise from the hydrorhiza as_ special 
organs. It is possible to mark out the blastostyle wall into 
the regions mentioned by Van Beneden and Weismann as 
gastral a, germinal 4, and cambium ¢, as represented in Pl, II, 
