244 DISCOVERY REPORTS 



ten months (pp. 428-9). An important conclusion reached is that Blue females become 

 mature sexually at about 78 ft., probably in June or July of the second year from 



birth. 



doubtful corpora lutea. During the examination of the ovaries preserved in 

 formalin (1934-5 collection) it was found that in ovaries which had large numbers of old 

 corpora lutea from about twelve upwards there were occasional yellow bodies lying 

 deep in the ovarian stroma and presenting the appearance of old corpora lutea. The shape 

 of these bodies, however, was long and thin, unlike that of the genuine old corpora lutea, 

 or more properly corpora albicantia, which are usually round or oval in cross-section, 

 and there were fewer striations to be seen. The average length was 1 cm. and width 

 0-3 cm. It was at first thought that these bodies might represent old corpora lutea of 

 ovulation or even of pregnancy. If this was so the conception of the permanency of 

 corpora lutea would largely fall to the ground and their accumulation could be taken to 

 represent increasing age only to a limited extent. If the corpora were to reach such small 

 size they might well be on the point of being completely reabsorbed. 



Dr A. S. Parkes kindly undertook to examine specimens of these corpora and compare 

 them with undoubted relics of previous ovulations. Stained sections showed that the 

 bodies were of definite luteal tissue, but with much less connective tissue in them. 

 The crucial point seemed to be that these small corpora were deep in the ovary, and that 

 no corresponding scar could be seen on the surface. A scar can always be seen with 

 genuine corpora lutea. It was finally agreed that these bodies were not relics of genuine 

 ovulations but had been caused by abortive follicles which had been on the way to 

 maturing and then had regressed, forming luteal tissue, owing perhaps to the formation 

 of a corpus luteum of pregnancy by another and better developed follicle. The luteal 

 body arising from such a follicle is called a corpus atreticum. 



It was therefore decided not to include these bodies in the counts of corpora lutea. 

 Only those corpora which showed their scars of origin were considered in assessing the 

 number of past ovulations. 



The corpora atretica were not so easily found in the ovaries preserved in salt, partly 

 because the flabbiness of the ovaries and their tough texture rendered slicing them diffi- 

 cult. Nor do I recall having seen more than two of these bodies in the fresh ovaries 

 which I examined in 1932-3. These were not included in the count. In the event of 

 future investigators using ovaries hardened in formalin, the distinction between corpora 

 atretica and corpora albicantia must be carefully borne in mind, or the count of total 

 corpora lutea may be inaccurate. 



length and corpora lutea. We now consider the ovaries of whales of 78 ft. and 

 upwards. 



The ovaries supplied by factory ships show some serious discrepancies. It was shown 

 in Fig. 5 that I found that whales up to 81 ft. have in general few corpora lutea. Four 

 whales showed one corpus, two showed two, there were none with three, one each with 

 four and six, and one (an 81 ft. whale) with seven. The sample here, 180 whales, was 

 twice as large as the average collection supplied by an individual factory and might be 



