104 EIGHTEENTH REPORT. 



body cavity of the frog, are carried into the open mouths of the 

 oviducts by the motion of cilia of the coelomic epithelium ; these 

 cilia drive anteriorly any solid objects lying free in the body cavity. 

 He states that the cilia are not uniformly distributed, but occur 

 in patches on the peritoneum of the body wall and mesentery. 

 Nussbaum's version of the matter has been quite generally accepted. 



In order to test the validity of Nussbaum's conclusions I took 

 several female specimens of Rana pipiens during the breeding sea- 

 son Avhen the eggs were still in the ovary, and tested the mesentery 

 and other parts of the peritoneum for ciliary action, using powder- 

 ed carmine, blood and cork filings. There was absolutely no evi- 

 dence of ciliary action. As a check on this experiment I used 

 the same means to detect ciliary action on the roof of the mouth 

 cavity and oespohagus of the same frogs, and obtained the most 

 lively evidence of ciliary motion. In like manner I have thoroughly 

 tested the peritoneum of female specimens of Cryptobranchus dur- 

 ing their breeding season, with absolutely negative results. In 

 both Eana pipiens and Cryptobranchus, I scraped the peritoneum 

 in various parts of the body cavity and by examining the scrap- 

 ings under the microscope found indeed that there were occasional 

 patches of cilia, but the foregoing experiments indicate that in 

 Cryptobranchus and in Rana pipiens ciliary action is not power- 

 ful enough to carry along foreign particles to any appreciable 

 extent, and certainly' not strong enough to move the large and 

 heavy eggs. In the absence of sufficient ciliary action, we must 

 look for mechanical factors to insure the transmission of eggs 

 to the oviduct. My observations and experiments have convinced 

 me that Newport's views, and not Nussbaum's, were essentially cor- 

 rect, at least when we attempt to apply them to the species under 

 consideration. The following conclusions were written by me be- 

 fore I was aware of Newport's theory. 



The funnel is so placed as to open in an anterior direction. Eggs 

 that by any chance get into it cannot easily get out by retrogress- 

 ive movements, since they are pressed u])on by other eggs and are 

 soon carried down the oviduct. Thus the funnel acts as a trap to 

 catch eggs. At the beginning of the process some eggs lying free 

 in the body cavity must get into the funnel by chance, aided by 

 the muscular movements of the animal which keep them in circula- 

 tion. These eggs are carried down the oviduct and collect in the 

 uterus. Since the uterus is located at the posterior end of the 

 body cavity while. the funnel is at the anterior end, the pressure 

 of the increasing mass of eggs in the uterus must force the eggs 



