2I 6 DISCOVERY REPORTS 



the shoulder joint, and a very large pyonephrosis. On several occasions a form of 

 pleurisy has been noticed in which there were extensive adhesions of the lungs to the 

 pleura. Such diseases have seldom been recorded, but might be observed more often if 

 it were not for the difficulty of examining the viscera. A degenerate or deformed foetus 

 has been seen from time to time, and such foetuses are generally large ones. Mr J. W. S. 

 Marr, working in the factory ship 'Terje Viken', found in a 75 ft. Fin whale five 

 foetuses measuring 8-14 ft. They were grotesquely deformed and had evidently been 

 long dead, for each was invested in a hard, stony concretion. A smaller concretion may 

 have represented a sixth foetus. The cow appeared to be in a perfectly healthy condition. 

 One or two instances of such a litter have before been known to occur, but it is doubtful 

 whether any survive to birth. 



Several whaling inspectors have from time to time observed whales with noticeably 

 tinted blubber. The colour has been described as pink, yellow or orange. It was noted 

 in both Blue and Fin whales, but only in one or two among many hundreds. I have 

 heard no definite explanation of it, but it may possibly be pathological. 



One other abnormality worth mention is an apparent example of albinism in a Fin 

 whale. Commander H. Buckle (whaling inspector in the ' Southern Empress', 1937-8) 

 reported a 68 ft. male Fin whale which was 'almost pure white'. 



BREEDING, GROWTH AND AGE 



In recent years a good deal of new material relating to the breeding, growth and age of 

 whales has been collected by members of the Discovery Committee's staff and other 

 biologists who have sailed in factory ships to the Antarctic. Work on this material, 

 which includes records of large numbers of ovaries, has been interrupted by the war, 

 but it is to be hoped that it will be resumed in the future, and much progress should be 

 revealed when the results are available. In the meantime this section of the present 

 report will be mainly confined to a summary of previous work and the general principles 

 on which breeding, growth and age have been investigated. Some comments also are 

 needed on the accuracy of previous estimations of the mean length at sexual maturity. 



THE MEAN LENGTH AT SEXUAL MATURITY 



The size and age at which whales become adult require special attention in any study 

 of the life history of whales. It is always important to be able to estimate the percentage 

 of immature whales in the catches, and almost any investigations of breeding and growth 

 must start with the distinction between the mature and the immature. 



It is found that whales of the same species and sex become adult at a length which 

 normally varies within rather narrow limits. Consequently, the majority of whales can 

 be distinguished as mature or immature by the length alone ; and having estimated the 

 average length at which whales become mature we can calculate with some confidence 

 the percentage of immature whales in catches for which only the species, sex and length 

 are recorded. 



