JAN 9 1099 



DEVELOPMENT OE THE PIG DURING FIRST TEN DAYS. 329 



The Development of the Pig during the First 

 Ten Days. 



By 

 Richard Asslicton, M.A. 



With Plates 25—28. 



Introduction. 



The history of the development of the roe deer, published 

 by Bischoff in 1854, contains almost the only account there is 

 of the early stages of the development of any Ungulate. The 

 .description which that distinguished embryologist was able to 

 give was, however, somewhat meagre, and does not offer much 

 assistance towards the solution of problems which occupy the 

 attention of embryologists of the present day. 



He was able to describe the external features of some of the 

 stages of segmentation, and made the very interesting dis- 

 covery, that in the deer the embryo, upon reaching the fully 

 segmented or morula stage, enters upon a period of quiescence, 

 and remains for some weeks unaltered. 



Von Baer (2), who made most careful observations upon the 

 later stages of development of both the sheep and pig, found 

 the egg of a sheep in the oviduct as early as the end of the 

 first day. His descriptions, however, of the earliest stages of 

 these animals, although historically interesting, are of little 

 use for our present purpose. 



Between 1884 and 1889 Bonnet (10, 11) published his work 

 upon the sheep, but in this he dealt with nothing earlier than 

 the twelfth day. 



VOL. 41, PART 3. — NEW SERIES. A A 



