531 
period of development, the crux of the matter lies in the mode of 
preservation. Dean appears to have made no use of osmic acid in 
his investigations. The only two reagents employed by me were 
FLEMMING’s fluid and corrosive sublimate. 
“Eggs preserved in the latter fluid show no signs of the eight 
furrows described by myself, unless any sublimate remaining in the 
superficial part of the egg be precipitated by some such reagent as 
baryta water, but all the eggs of the proper stage (Fig. 3 of BALFOUR 
and PARKER’s memoir) show either four or eight complete furrows 
reaching to the lower pole. It is so easy to see these furrows in 
eggs lying in alcohol, or in eggs passed through turpentine and then 
dried, that I have often demonstrated them to others”. 
During the spawning period of 1897 I secured a large number of 
adult fishes and notwithstanding the fact that they were badly mangled 
by the spear, the eggs and sperm were in excellent condition and 
artificial fertilization easily accomplished. The eggs were fertilized 
in earthen dishes, to the sides and bottom of which they remained 
attached until the embryos hatched. From the material thus obtained 
several embryological series were preserved comprising the stages. 
between the unsegmented ovum and the 25 mm larva. In preserving 
the eggs the following fixatives were employed: Formaline, 8°/,—10°/, 
aqueous solution, Chrom-osmo-acetic, Corrosive -sublimate- acetic, 
PERENYTS fluid, Picro-acetic and Picro- 
sulphuric. 
The following remarks concerning RE 
the cleavage are based upon a detailed kik \ 
examination of the surface phenomena, i 
as presented in both the living and / 
preserved material, supplemented by a | 
study of serial sections of corresponding | 
stages. } 
In nearly all the eggs which were 
fertilized at 11 A. M. the first cleavage 
had appeared by 1P.M. This cleavage 
in the living egg is foreshadowed by 
a flattening of the upper pole of the Fig. 1. 2 hrs. 23 min, after 
egg, which in reality is a thinning ‘rtilization. 
of the calotte or blastodermic area, 
a wide shallow furrow is first noticeable and this in turn gives 
rise to a narrow deep fissure or cleavage groove. This groove soon 
extends in either direction over the surface of the egg giving rise to 
34* 
re 
nn 
