206 
CHAS. H. O’DONOGHUE. 
to provide the solid matter necessary for the production of the 
milk, the cells of the gland would have to be renewed about 
five times a day. Heidenhain’s theory has been maintained 
in the researches of Frommel ( 16 ), Steinhaus ( 44 ), and 
Dulcert (12), who also state, in support of it, that they have 
found mitoses in all stages of the activity of the gland, by 
means of which the cells and nuclei that have been destroyed 
are replaced. Michaelis ( 36 ), with slight modifications of no 
fundamental importance, also supports the view that the 
nuclei by their degeneration take an active part in milk- 
formation, but says they are replaced amitotically. 
Contemporaneous with these works, however, we have 
Bizzozero and Vassale (loc. cit.) and Benda (loc. cit.) still 
upholding the theory of pure secretion, and contending that 
no necrobiosis of either the epithelial cells or their nuclei 
occurs. The latter author attributes the torn edges of the 
cells lining the alveoli and the presence of nuclei therein to 
faulty technique, and further states that he has seen no stages 
of mitosis or amitosis. These views have again been borne 
out by Unger ( 47 ). 
Considering now the most recent writers on this subject, 
first we have Simon ( 33 ), in 1902, who adopts in its entirety 
the theory of Heidenhain, and states that the replacement of 
the nuclei takes place by amitosis. He divides the secretory 
changes into three parts : (1) The phase of cellular secretion, 
(2) the phase of cellular excretion, and (3) the phase of cell 
reconstruction, and it is in the second of these he describes 
the cell as becoming decapitated and often, in addition, losing 
a nucleus. Next, Bronha 1 (loc. cit.) in 1905 also records 
this decapitation phenomenon, and comes to the conclusion 
that the normal constituents of milk are produced by two 
processes: (1) The fatty parts are produced by an ordinary 
secretory activity of the glandular cells. (2) The albuminous 
matter results from a necrobiotic activity in which a part of 
1 This work of Bronha contains a very full bibliography and discus- 
sion of the subject up to date, which should be consulted in the inves- 
tigation of this matter. 
