NEOPLASTIC DISEASES IX CHICKENS 



35 



index for the entire flock from which these chickens came was, as previously in- 

 dicated, 0.534 for the first 150 days of productive life. For the group with leio- 

 myoma, the index was 0.615, with a range from 0.418 to 0.810, and only five hens 

 had an index below the average of the flock. These figures become even more 

 significant when it is considered that the production index for the group with 

 leiomyoma was calculated for a period extending beyond the first 150 days of 

 production, which is the period of heaviest egg production. The interval between 

 the last egg laid and necropsy averaged only 12 days, with a range from 1 to 73 

 days. Such a short interval would seem to indicate that the slow-growing leio- 

 myoma interfered but little with egg production. 



Table 17. — Data on Egg Production of Chickens with Leiomyoma. 



Productive life is the interval between first and last eggs laid. 

 Production index is the factor obtained by dividing the number of eggs laid 

 by the productive life in days. 



*K indicates that bird was killed for examination; D, that it died. 

 **Tumor located in both ligament of oviduct and oviduct. 

 ***Tumor located in oviduct only. 



In all other cases, tumor located in ventral ligament of oviduct. 



The location of leiomyoma in the ligament of the oviduct and the heavy egg 

 production of chickens with this tumor lead to speculation of a causal relationship. 

 The report of Curtis (2) outlines well the musculature of the ligaments of the ovi- 

 duct, which is greater in amount in the ventral ligament than in the dorsal liga- 

 ment. Curtis indicated that the smooth muscle fibers of the ligaments were 

 directly connected with the muscle fibers of the wall of the oviduct and that 

 musculature in the ligaments must contribute to the physiological motility of the 

 oviduct. Greatest activity would occur during periods of egg production and 



