. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. THE REPRODUCTIVE ORGANS 403 of the milk. Sometimes the outHnes of these droplets is in the form of a complete circle; at other times (possibly when the gland has been emptied by suckling) the outlines are broken up or fragmentary. Where an osmic acid fixative is used the droplets are densely blackened, no doubt owing to the very high percentage of fat which is present in whale's milk. In such cases the droplets within the lumen of the cells are similarly blackened. The depth of the mammary gland
. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. THE REPRODUCTIVE ORGANS 403 of the milk. Sometimes the outHnes of these droplets is in the form of a complete circle; at other times (possibly when the gland has been emptied by suckling) the outlines are broken up or fragmentary. Where an osmic acid fixative is used the droplets are densely blackened, no doubt owing to the very high percentage of fat which is present in whale's milk. In such cases the droplets within the lumen of the cells are similarly blackened. The depth of the mammary gland during the secretion of milk varies in Blue and Fin whales between about 15 and 30 "'i '*â . >'i; '; i -^ .,. â¢â â :- â .'.--:r-,. â â .â¢â ; " -%.v ' â .â 'â â :â :â¢..â¢: : ;= -â ^^'â .â 'â ^-j Fig. 135. Section of the immature mammary gland. Fig. 136. Section of mammary gland in functional activity. The intermediate stage occurs in certain sexually mature whales in which the mammary glands are not functionally enlarged. It has been seen that during lactation the lobules become greatly swollen and compress the intervening connective tissue into the smallest possible space. In the intermediate stage the lobules appear either to have started swelling in preparation for lactation, or, more often, are in the process of contracting after the end of lactation. This, condition is never found in pregnant whales except at the very end of gestation, but it is curious that it occurs more often in "resting" whales than the normal resting condition which is almost always present in pregnant whales. The lobules are still large (Fig. 137), and, though noticeably smaller than in lactating whales, they are considerably better developed than in the resting stage. The connective tissue space is still restricted, but the alveoli are shrivelled and smaller than in the lactating gland, their outline is less easily traced, and their lumen, at
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