392 
CHIYOMATSU ISHIKAWA. 
advice and never-failing encouragement I am very much in- 
debted. 
To the authorities of the University of Tokio, and especially 
to the President, Mr. H. Kato, I am deeply indebted for the 
use of the instruments, chemicals, and other things necessary 
for pursuing my work. 
I must here also express my great obligation to Dr. Faxon, 
for sending me ‘ The Memoirs of the Museum of Comparative 
Zoology at Harvard College,’ vol. ix, No. 1, which was of 
great use to me. 
Methods. 
For the dissection of the ovary, I have used Zeiss’s Dissecting 
Microscope, with a magnifying power of about fifteen diameters. 
For examination of fresh specimens : 
a. Ovaries were examined in bicarbonate of potash or of 
ammonia 2 per cent, strong. Connective tissues were treated 
with acetic acid per cent.) and coloured with aniline. 
b. Embryos were removed from the yolk mass by means of 
needles in the normal salt solution, and exposed to the fumes 
of osmic acid ( 05 per cent, strong) for about five minutes. 
For the surface view of the ovarian walls, nitrate of silver 
was always employed. 
For sections embryos were hardened in Kleinenberg’s picro- 
sulphuric or Mayer’s picro-nitric acid for about three hours, and 
passed through successively weak, strong, and absolute alcohols. 
They were then stained in the logwood-solution or borate of 
carmine. In the former fluid the yolk-spherules were coloured 
magnificently, while in the latter they remained uncoloured. 
Books of references are noted throughout this paper by the 
use of the Arabic numerals. The denominators in the frac- 
tions refer to the list of authors at the end of this paper, and 
the numerators indicate the page. There are, however, many 
works to which I could not get an access. These are referred 
to, as far as possible, by citations found in those books at my 
command. Such works ai’e noted in the list by an asterisk. 
