762 | The American Naturalist. [September, 
a controversy with Reichert, over the existence of a vitelline membrane 
on the surface of the eg 
Similar wrinkles have since been observed in the eggs of the common 
toad by Goette (Die Entwickelungsgeschichte der Unke), and of Am- 
blystoma punctatum by Eycleshymer (Journal of Morphology, Vol X). 
But neither of these authors offer any explanation of their origin. So 
far as known this “ Faltenkranz” has never been described for any 
American species of frog, nor has any attempt been made to study it 
by means of serial sections, 
The followiag paper is offered as a contribution of some new and in- 
teresting details in the occurrence of the phenomenon, together with 
the results of a microscopic study of sections, in the hope of arriving at 
a rational conclusion as to its origin. 
The author desires to acknowledge his great indebtedness to Dr. E. 
A. Andrews, for the suggestion which led to the study, and for much 
subsequent assistance. Thanks arealso due to Prof. T. H. Morgan, for 
the kindly loan of a copy of Schultze’s paper. 
FORMATION OF THE WRINKLES. 
The eggs of a small wood-frog, in all probability Chorophilus triseri- 
atus, were obtained for class work on March 27, 1896 
They were unsegmented when found, and were immediately placed 
in ice water to check any further development. 
After remaining thus for five hours they were used in the laboratory, 
being removed to watch-glasses containing tepid water. Some were 
allowed to remain in the ice water for eight hours before being exam- 
ined, and it was noticed that these segmented much more rapidly than 
the ones which had been kept only five hours. Actual segmentation 
had been prevented during the stay in the ice water, but there seemed to 
have been a storing-up of energy, a sort of preparation for segmenta- 
tion, so that when removed to a favorable environment the process 
began very quickly (5-10 mins.) and was carried on much faster than 
it would have been normally. 
These eggs were obtained from pools covered with ice quarter of an 
inch thick, and most of the bunches were quite near the surface. 
This must occur frequently where the eggs are laid so early in the 
spring; and according to Morgan (AMERICAN NATURALIST, August, 
1891), Chorophilus always lays its eggs very early. 
The storage of energy noticed above may suggest a natural method 
of compensation whereby the warm sunshine of mid-day may offset the 
freezing cold of the nights, and in this way the eggs will really lose 
 wery little time in their development. 
