1883.] Zoology. 433 
This origin of the sexual products independently of and pre- 
vious to the formation of the sporosacs, appears at first sight to 
militate against the theory of the alternation of generations, and to 
reduce the sporosacs, demi-meduse and medusa of the fixed hy- 
drosomes to the rank of reproductive apparatuses. But,to say noth- 
ing of the fact that the observations only refer to a few forms, and 
must be greatly extended before the facts proved can be accepted 
as general, there remains the other fact that the limits of the 
meaning of such words as “reproductive apparatus,” “ organ” 
and “individual” are not definitively settled. Even a young 
mammal is in a sense a “ reproductive apparatus” specialized for 
the purpose of carrying on the species, and in the hydroid sporo- 
Sac we simply have one of the lowest terms of a series that cul- 
minates in an independent organism. 
. de Varenne finds that the ova and parent-cells of the sper- 
matozoa come to occupy in the gonophore a position apparently . 
above the endoderm, because their accumulation divides the endo- 
derm into two portions, allowing their escape. Subsequently the 
break in the endoderm is made good beneath the sexual products, 
but is always surrounded by a thin lamella secreted by this new 
formation, and the intermediate lameila found in the stem of the 
hydroid covers also the ova in the sporosac, although in the lat- 
ter it is so compressed that it is hard to perceive. 
M. de Varenne has traced the complete series of changes by 
which, in one hydrozoan, the cell becomes an ovule. The first 
Step is the suppression of the flagellum of the endodermic cell, 
then follow great increase in size, augmentation of the nucleus 
(which becomes highly refractive) and the assumption of the 
rm 
cells endowed with power of spontaneous oscillation. 
Huxley, Keferstein, Kleinenberg, Schulze and others have stated 
ar the sexual products of animals proceed from the ectoderm, 
while others derive the ova from the endoderm and the sperma- 
tozoa from the ectoderm, and still others reverse ne Š i 
e interesting query is—Does the development of these ele- 
ments follow ie kame Tok throughout the sahal series 
DısTRIBUTION oF Unto pressus (Lea).—Mr. A. F. Gray’s notes 
hee species in Amer. Naturatist (Feb., 1883) recall my own 
‘vations on it. Dr. James Lewis found it in the outlet of 
Owasco lake, a tributary of the Seneca river, but in extensive 
collecting in that river I have obtained but one specimen. In 
“ome small streams flowing into it, however, it is abundant, and 
Sometimes of very large size. I have also observed it sparingly 
