128 GEORGE W. CORNER 



origin of the corpus luteum, but his description shows that he 

 Mas probably including the theca interna as part of the granulosa. 

 The little dissertation must remain as a not uninteresting example 

 of the effect produced upon the work of an active student by the 

 recently announced cellular theories, rather than as an important 

 contribution to its subject. 



The next to use the sow for study was Paladino (79, '80, '81, 

 '87), who collected about 500 corpora lutea of 100 sows. His 

 extensive papers propose a peculiar theory of his own, namely, 

 that the entire granulosa is lost before rupture of the follicle, and 

 that the theca externa, carrying blood-vessels, proliferates in- 

 ward, to form the corpus luteum tissue, pushing the theca interna 

 before it to form a central connective-tissue core. In 1900 and 

 1905 he repeated his views of twenty years before in criticism of 

 Sobotta, who pointed out in return that Paladino 's writings con- 

 tain no evidence at all, in text or plates, that he had ever seen 

 developing stages of the corpus luteum; a just criticism, as study 

 of the originals has convinced me. 



Far different is the work of Benckiser ('84), who has given a 

 very careful description of a small series of stages. He had, 

 without doubt, normal and mature Graafian follicles just prior 

 to rupture. These contained the membrana granulosa intact. 

 In his recently collapsed follicles, containing large clots, the gran- 

 ulosa had been torn off in places; when there was no hemorrhage, 

 this layer remained very largely in situ. His next stage is much 

 further developed, its wall showing only one homogeneous layer, 

 and the gap was bridged by the assumption that the granulosa 

 had degenerated during the interval. The account is clearly 

 written, its author was describing what we can now state to be 

 normal specimens, and it was only lack of sufficient intermediate 

 stages that led him into an error of interpretation. 



One of the most frequently quoted works is that of Clark 

 ('98), whose material consists of ovaries collected at random in 

 the slaughterhouse. It is said that among the sows used by the 

 butchers there were many undergoing oestrus, but it is not stated 

 that any of those ovaries used in the research were known to be 

 from the animals in heat. Clark gives a good description of the 



