NOTE ON MULTIPLE OVULATIONS 



Three of the female Fin whales captured during 1929-30 possessed more than one 

 apparently functional corpus luteum in the ovaries. 



No. 2798 was captured in December. It had twin foetuses, a male of 1-04 metres 

 and a female of i-o6 metres, and in one of the ovaries three large corpora lutea, all with 

 the characteristics of the functional corpus luteum of pregnancy, were found. The sizes, 

 measured in three directions at right angles, were as follows: 13 x 15 x 5-5 cm., 

 13 X 14 X 7 cm., 8-5x7x7 cm. The tissue of each was soft, somewhat yellow, and 

 stained deeply with both Nile Blue and Osmic acid. Obviously three ova had been 

 shed at one ovulation and two of them had been fertilized. 



No. 2815 was brought to the station three days later. No foetus was present but 

 there were two corpora lutea in one ovary and one in the other. These appeared to be 

 functional from their structure and staining reactions. The sizes were 11-5 xi2-5 x 4 cm., 

 5-5 X 4 X 2-2 cm., 2-2 X 4-5 X 4-5 cm. 



In whale No. 2874 a male foetus was present, 0-41 metres long, and in the ovaries 

 there were two apparently functional corpora lutea, one measuring 19 x 16-5 x 7 cm., 

 the other 8-5 x 6-5 x 4 cm. 



Among the whales examined by Messrs Eraser and Rayner in season 1928-9, one 

 Fin whale possessed male twins of 3-72 and 3-67 metres. There were two large functional 

 corpora lutea, one in each ovary, measuring 15x15x8 cm., 15 x 14 x 12 cm. 



The above observations show that a very small percentage of whales liberate several 

 ova at one ovulation, and thus provide an explanation of the multiple foetuses occa- 

 sionally reported. 



It is curious that when three ova are shed and two are fertilized, two corpora lutea 

 remain large while the third dwindles; that when two ova are shed and both are fer- 

 tilized, the corpora lutea are both of large size; while if two ova are shed and only one 

 is fertilized only one corpus luteum maintains its size. 



These facts suggest a close and somewhat exclusive relation between corpus luteum 

 and foetus. If two ova are fertilized then two corpora lutea will remain functional, if 

 one foetus is developing then one corpus luteum is sufficient. Perhaps, indeed, the 

 corpus luteum reflects the fate of its own released ovum. 



Multiple foetuses have been reported from a number of localities in both the Northern 

 and Southern Hemispheres. Haldane (1910, p. 117) gives the lengths of six foetuses 

 from a Common Rorqual taken off Iceland, but does not record the sexes or details 

 of the ovarian condition (see also Collett, 1911-12). Seven foetuses were taken from 

 a Blue Whale at South Georgia in 1924-5 and the lengths, weights and sexes were 

 reported in the Norsk Hvalfangsttidende (Risting, 1925, pp. 98, 99) where reference 



