THE CORPUS LUTEUM 357 



range of variation 6-2-17-5 cm. The lower limit is the smaller of two corpora lutea associated with 

 twin foetuses and the smallest corpus luteum from a uniparous pregnancy is 7-5 cm. The frequency 

 distribution of corpus luteum diameter is shown in Text-fig. 7. 



There are 372 records of the weight of fin-whale corpora lutea. The mean weight is o-88i ±0-04 kg. 

 and the range 0-2-2-4 ^g- The frequency distribution is shown in Text-fig. 7. Chittleborough (1954) 

 suggests that there is a relation between the weight of the corpus luteum and the age of the female 



05 



10 is 



WEIGHT IN KILOGRAMS 



20 



523 C.L PREGNANCY 



59 CL OVULATION 



26 CL ACCESSORY 



IO 

 DIAMETER 



15 

 IN CMS. 



20 



25 



Text-fig. 7. Frequency distributions of weights and diameters of corpora lutea. 

 The means ± 2 S.E. are shown. 



using the total number of corpora in the ovaries as an index of relative age. He found an increase 

 in corpus luteum size with increasing age. In fin whales no such increase in size could be demonstrated. 

 In Text-fig. 8 average corpora lutea weights at different diameters have been plotted on a double 

 logarithmic scale for 372 fin whales. Five blue-whale records and three sperm-whale records have 

 been added at the upper and lower limits of the size range. This gives a linear relationship, as is to be 

 expected, and suggests a probable maximum weight for the extreme fin-whale corpus luteum diameter 

 (17-5 cm.) of 3-2 kg. Thus the extreme weight range in this larger sample is from 0-14 to 3-2 kg., a 

 sixteen-fold increase from smallest to largest, as compared with a less than three-fold increase in 

 diameter (6-2-17-5 cm -)- 



