LACTATION 561 



disintegrated. It is believed, however, that some cells simply 

 discharge their fat droplets and other contents into the lumina, 

 while otherwise remaining intact. 1 



Steinhaus states that mitotic division of the cell nuclei in 

 the actively secreting mammary glands is of frequent occur- 

 rence, and that the daughter nuclei which lie in the outer portions 

 of the cells degenerate and share in the general process of dis- 

 sociation. Szabo 2 also records the occurrence of two or more 

 nuclei in the same cell during lactation, and similar evidence 

 of nuclear division has been observed by others. Moreover, it 

 is argued that this view is in no way inconsistent with the 

 generally accepted homology between the mammary and 

 sebaceous glands, since it is easy to understand how, in the 

 course of evolutionary development, the mode of secretion in the 

 glands in question might have undergone an alteration, whereby 

 the process of disintegration in the actively secreting cells 

 became gradually lessened as the character of the secretion 

 changed. On the other hand, if we suppose that the cells of 

 the mammary gland merely extrude their secreted materials 

 without undergoing any histological disintegration, it is more 

 difficult to uphold the homology in question. Lastly, it should 

 be mentioned that those who, like Steinhaus, support the theory 

 of partial disintegration, do not regard the colostrum corpuscles 

 as detached epithelial cells, as Heidenhain did, but agree with 

 those who uphold the purely secretory theory in supposing the 

 corpuscles to be of the nature of " mast cells," or basophil 

 leucocytes which have wandered inward from the connective 

 tissue of the gland, as already described, and have made their 

 way into the lumina of the alveoli. 3 



1 Brouha, loc. cit. ; also " Les Phenomene's histologiques de la Secretion 

 lactee," Anat. Anz., vol. xxvii. 



* Szabd, " Die Milchdriise im Ruhezustande und wahrend ihrer Thatig- 

 keit," Arch. f. Anat. u. Phys., ana/. Abth., 1896. 



3 For references to further literature upon the physiology of milk forma- 

 tion see Basch, "Die Physiologie der Milchabsonderung," Ergeb. des Phya., 

 1903, Jahrg. See also the following for references to the histology: 

 Bizzorzero and Ottolanghi, " Histologie der Milchdriise," Merkel and Bonnet's 

 Ergeb. d. Anat. u. Entwick., vol. ix., 1900, and von Ebner, "Von der Ge- 

 schlechtsorganen," Kolliker's Handbuch der Gewebelehre dee Menschen,\o\. iii., 

 1902. 



2N 



