BY F. P. SANDES. 



391 



recentl}' been described by Regaud, Policard and others, and also 

 that they do not show (except occasionally) mitotic figures, 

 though on this last point authors disagree. The corpus luteum 

 of Dasyurus comes into line with other corpora lutea in these 

 respects, and, like them, resembles closely the liver in its histolo- 

 gical features. Prenant considers the corpus luteum a gland, and 

 he is of opinion that its hypothetical secretion plays an important 

 part in the organism, such as we are accustomed to attribute to 

 the supposed ovarian internal secretion. After attempting to 

 explain the phenomenon of chlorosis by the lack of this possible 

 internal secretion, he proceeds to argue that the purpose of the 

 corpus luteum is probably also to prevent ovulation in the period 

 between successive oestra, or during pregnancy. This latter 

 theory is supported by Beard, Regaud and Policard; and in the 

 case of Dasyurus can be supported on the following grounds : — 

 On taking a general view of the ova and their intraovarian 

 history in Dasyurus, it was observed that, in common with other 

 animals, during the period between the oestra, and towards the 

 end of lactation, the corpus luteum disappeared, and then the 

 young ova began to grow in pre^^aration for the next oestral 

 period. Also, as soon as the corpus luteum is formed, it is found 

 that the ova, hitherto in various active stages of development, 

 begin to atrophy as described above. This atroph}^ begins in the 

 neighbourhood of the young corpus luteum, and the process seems 

 to affect the ova in ever widening circles. This atrophy may be 

 due partly to mechanical pressure and partly to the internal 

 secretion of the corpus luteum, if it has one. It is at an}^ rate 

 certain that, in Dasyurus during the time of development and 

 persistence of the corpus luteum, atrophy of the larger remaining 

 ova takes place, and ovulation remains at a standstill. Some of 

 the remaining ova (exceptions to the rule) have at first sufficient 

 energy to carry them on for a while, but ultimately the corpus 

 luteum triumphs over them and they atrophy. 



In this connection, Fraenkel and Cohn's experiments (see Anat. 

 Anz. 1902, pp. 294-300) are of interest. Working on Born's 

 theory, that the corpus luteum is a gland elaborating an internal 



