THE HUMPBACK WHALE 



55 



the whale was pregnant with a 075 m. foetus. The fluid in the gland may possibly have 

 been due to a pathological state, but this point is discussed further below. The thickness 

 of the gland in this whale was only slightly above the minimum for the involuted state. 

 The lactating class requires no explanation : the thickness of the gland was recorded in 

 only one whale, from whose nipples the milk was spouting in a stream when it was 

 drawn up on the flensing plan. In this the thickness was 15 cm., as thick as the lactating 

 gland in many Blue whales. 



E 



a 



c 



in 

 in 



c 

 -^ 

 o 



x: 



r 

 14 



15 



12 13 



Total Length in metres 



• Non parous 

 O Involuted 

 ® JnTermediaTe 

 □ Lactating" 



Fig. 52. Humpback whale. Females. Size of mammary gland. 



The great thickness of the mammary glands in all their stages when compared with 

 those of Fin and Blue whales is striking, especially when it is borne in mind that the 

 length of the gland is not much less than in those species. The length in Fin and Blue 

 whales is given as about 2 m.: no measurements of length are recorded in the present 

 series, but Lillie (1915) records that in a 40 ft. humpback at New Zealand the gland was 

 5I ft. long (approximately 12-25 m. body length: 17 m. gland length). It appears then 

 that the mammary gland of the Humpback will produce much more milk in proportion 

 to the length of the whale than in whales of the genus Balaenoptera. This point is dis- 

 cussed further in a later section in connection with the growth of the young. 



Gestation and breeding season. In addition to the records of foetal length collected 

 in South Georgia and South Africa, particulars relating to a few pregnant female 

 Humpback whales from the South Indian Ocean are available. In the season 1932-3 

 Mr A. H. Laurie examined a series of whales on board the Southern Whaling and 

 Sealing Company's floating factory ' Southern Princess' in that area. In the month of 

 November 1932 nineteen female Humpback whales were captured, and details of eight 

 are given in Table XVI. In the British Museum statistics relating to whaling there is 

 an extensive list of dated records of foetal Humpback whales, given here in Table XVII. 



