200 
MR. NEWPORT ON THE IMPREGNATION OF 
minutes, and segmentation commenced at three hours and Jifty-six minutes, and was 
general in two minutes longer, at which time the temperature of the dark cupboard 
in which the ova of this set of experiments were placed had been raised to 64° Fahr., 
and that of the water they were contained in to 60° Fahr. 
In four days and a half, thirteen of these ova had produced embryos that were then 
at the end of the third period of development, and on the eighth day the whole of 
them had advanced to the period when they leave the ovum and attach themselves 
to the exterior of the envelopes, — the end of the fourth period of development. The 
mean temperature of the locality in which these ova and the embryos produced from 
them were placed, was about 60° Fahr. for the entire period of eight days. 
No. 2. p.M. 55™. — Forty-eight ova were touched once, as they passed from the 
body of the frog, with a hair-pencil that had been dipped in a small quantity of 
residual fluid retained with spermatozoa on a filter, in separating these from the fluid 
portion of frog’s semen, obtained and mixed with water forty minutes previous. 
The temperature of the cupboard having been raised as in No. 1, segmentation 
commenced in three hours and jifty-jive minutes, but was more general in four 
hours. Many of these ova were only partially impregnated, and of consequence did 
not produce embryos. Others passed through their changes, as in No. 1, and in 
nearly similar periods of time. On the eighth day ten embryos had been produced. 
No. 3. p.M. 2'* 3™. — Fifty-seven ova were well bathed as they passed from the frog 
with the fluid portion of semen that had passed through two filter papers and been 
separated from most of the spermatozoa, and which when examined with the micro- 
scope was found to contain only a very few of these bodies. 
No segmentation had taken place in any of these ova at the end of four hours and 
five minutes, but several had become ovoid. At four hours and thirty-seven minutes 
segmentation had taken place in one ovum, and this alone produced an embryo. 
*Se^ I, March 20, 1850. Atmosphere 48° Fahr. Water 47° Fahr. — This set was 
the counterpart of the preceding. Set H. 
No. 1. p.M. 15™. — Nineteen ova were treated in exactly the same way as in 
No. 1 H, and at the expiration of ten minutes were removed to fresh water, and placed 
where they were most exposed to light. 
No segmentation occurred in any of these ova until the expiration of seven hours 
and forty-five minutes. The temperature of the room had then sunk to 47° Fahr., and 
that of the water with the ova to 46° Fahr. All the changes in these ova were so 
exceedingly slow, that at the end of the eighteenth hour, the temperature during 
the interval becoming slightly further reduced, the segmentation of the yelk had not 
advanced further than to the formation of the first equatorial and secondary median 
furrows. On the fifth day the development of the germ had not proceeded further 
than to the commencement of the formation of the area germinativa, the end of the 
second period, the mean temperature during the interval having been 45°'49 Fahr. ; 
while the ova in No. 1 H had reached the end of the third period, the mean tern- 
