Atresia Ani* 



By A. T. Kinsley, M. Sc, D. V. S., Pathologist, Kansas City 

 Veterinary College, Author of "Veterinary Pathology" etc. 



During the embryonic stage of intrauterine 

 life the specialized tissues and organs are formed. 

 The fetal period is the time during which the 

 structures formed in the embryonic stage grow 

 and develop. At birth the young of a given 

 species are of a definite shape, contour and type; 

 the form or type which is most common is ac- 

 cepted as normal; and deviations from the nor- 

 mal are designated malformations, anomalies or 

 developmental errors. Many new strains and 

 breeds of live stock have been the result of de- 

 velopmental errors becoming a fixed peculiarity. 

 Thus the polled cattle, the Boston bull-dog, the 

 Mexican (hairless) dog, and the five-toed chicken 

 had their origin. 



A variety of malformations are of course 

 seen at the season when veterinarians are called 



'Reprinted ttom the Mitaouri Valley Veterinary Bulletin, June, 190S. 



