176 STATE BOARD OP AGRICULTURE i 



investigators in cases in which there has been loss of cotyledons at a 

 previous parturition. We have observed this condition in cases in whicli 

 neither the history nor the gross anatomical findings would indicate that 

 its development was the result of loss of cotyledons at a previous par- 

 turition. The thought is suggested that it may develop as a result of 

 the degenerative changes in the maternal and chorionic epithelium re- 

 ferred to a'bove and may possibly be interpreted as nature's method of 

 compensating for those changes in the epithelium that influence the 

 interchange of nutritive and metobolic products between dam and fetus. 

 This hyxjotliesis. we believe, is justified by the observations already made 

 but a great deal more investigational work must be done before con- 

 clusions may be drawn. 



There is another condition observed that we are unable to explain. 

 The extent of granular degeneration and necrobiosis of the chorionic and 

 maternal epithelium is marked. Naturally, in this condition one would 

 expect to find extensive denuded areas of the placenta. Such is not the 

 case. We have attempted to explain tliis in our own mind by assuming 

 that the vegetative type of epithelium found here possesses marked re- 

 generative properties and that repair is very active. Whether this 

 explanation is the correct one, further investigation only will determine. 



In our studies of involution and evolution of the uterus we have ob- 

 served many denuded areas of the maternal placenta in the evoluting 

 uterus but we believe tliat a great deal of this is the result of phogocytic 

 activity of the chorionic epithelium or the result of the action of the 

 enzymes elaborated by the chorionic epithelium. We are inclined to 

 believe that in the development of the maternal crypt, much of the ma- 

 ternal epithelium is destroyed and the crypt wall later becomes covered 

 with regenerated epithelium. If this is true the condition would favor 

 the entrance of bacteria that were in the uterus at the time of concep- 

 tion or that later gained entrance to the pregnant uterus, into the ma- 

 tei-nal tissues. In fact our observations on this problem lead us to 

 believe that the clianges in tlie placenta are continuously progressive 

 up until approaching parturition and that eroded areas of maternal 

 tissue may be found at any stage of pregnancy, such areas possibly favor- 

 ing the invasion of the maternal tissues by bacteria already present or 

 gaining entrance to the uterus at any stage of pregnancy. 



At this time we wish to acknowledge the valuable assistance of Mr. 

 I. F. Huddleson of the Department of Bacteriology who has made the 

 bacteriological examination of the cases studied in these investigations. 



Respectfully submitted, 



^ E. T. HALLMAN, 

 Animal Pathologist. 



