MICHIGAN ACADEMY OF SCIENCE. 103 



egg iimnediatelv louiids up into an oblate spheroid, considerably 

 flatter than the egg at the time of spawning. 



At the time when the egg is half-way out of the ovary it is con- 

 stricted to a remarkable degree: the stalk connecting the two 

 halves of the egg is scarcely more than 2 millimeters in diameter, 

 while the diameter of the entire egg after it assumes the spherical 

 form exceeds () millimeters. The plasticity of the egg at this time 

 contrasts strongly with its condition during early cleavage. In 

 the tirst cleavage stage I attempted to separate the first two blas- 

 tomeres by tying a silk thread around the egg in the plane of the 

 first cleavage furrow ; the egg would not bear a constriction of 

 more than 2 millimeters, leaving the constricted portion more than 

 4 millimeters in diameter. The greater plasticity of the ovarian 

 egg seems to be due to a lesser degree of turgor, or tension of the 

 egg membrane; perhaps the egg later absorbs water. 



As in Bufo (King, '02), the egg doubtless escapes through the 

 stalk of the follicle, since here the egg is enclosed by only two 

 cellular membranes, elsewhere by three. Since only a small pro- 

 portion of the eggs are found escaping from the ovary at any given 

 time, the liberation of all the ripe eggs must require a considerable 

 period of time, probably several days. 



2. The passage of the eggs down the oviduct. In Ciyptobranchus, 

 peristalsis of the uterus and the lower oviduct was observed, but 

 none in the upper oviduct. An egg placed in the funnel of the 

 oviduct of a prostrate specimen moved down the oviduct very 

 slowh^ At the end of an hour it had moved 2 centimeters further 

 than the position to which it may have been carried by gravity. I 

 scraped the lining of the upper oviduct and examined the scrapings 

 under the microscope; the epithelial cells possessed cilia. One can 

 only conjecture whether the ciliary action in the oviduct is strong 

 enough to carry the eggs along; possibly it is aided by peristaltic 

 action too slow to be observed. 



3. Hoio do the eggs get into the oviduct? Newport ('51) be- 

 lieved that, owing to the close attachment of the oviducts at their 

 inner openings to the walls of the pericardium, at each contrac- 

 tion of the heart the slit-like openings of the oviducts would gape 

 open, and any eggs in the vicinity might be forced, by suction, into 

 the mouths of the tubes. Also, he thought that owing to the 

 muscular movements of the body, and the resultant shifting of the 

 internal organs, the eggs sooner or later pass near the openings of 

 the oviducts, and are then carried into the tube. According to 

 Nussbaum ('95) the eggs, when set free from the ovary into the 



