THE GENERATIVE APPARATUS 381 



not the case. And I believe therefore that Halban's symptom of increase of 

 growth in youthful gravida does not depend so much on increase of hypo- 

 physial function but rather much more on the periodically increased vitality 

 of the whole organism when the epiphysial junctures are open. 



Let us now return to the behavior of the ductless glandular apparatus in 

 pregnancy. I must here mention the fact known already in antiquity that 

 during pregnancy there is increase in volume of the thyroid gland. There 

 develops a parenchymatous struma that feels soft on palpation. There is 

 indeed no doubt that this increase in volume is associated with a slight in- 

 crease in function, that is even a partial phenomenon of the increased 

 vitality. 



An increase of function of the parathyroids and of the pancreas can be 

 inferred by us only indirectly, from the fact that the latent insufficiency of 

 these glands tends to be manifest during this period; we have grounds for 

 assuming that this occurs as a consequence of increased demands and there- 

 fore that normally the function of these ductless glands is increased. 



We will now describe the changes undergone during pregnancy by the 

 mammary glands. First of all I will make some remarks as to their devel- 

 opment. Halban, whose important works we have to thank for our informa- 

 tion, distinguishes four periods of grow-th impulse separated in point of time. 

 The first falls about in the time between the eighth and ninth lunar months 

 [of embryonal life]. The second , occurs at the time of puberty, the third 

 always recurs at the premenstrual periods, and the fourth, especially inten- 

 sive, occurs during pregnancy. The ovaries constitute the trophic center for 

 the first three growth impulses. This may already be seen by the fact that 

 in disturbances in the development of the ovaries the breasts too remain 

 undeveloped (Foges) . The growth impulse during puberty leads as is known 

 to a noticeable development of the glandular parenchyma. The growth im- 

 pulse in the premenstrual periods can in rare cases be so strong that in virginal 

 individuals colostrum may be secreted, and later, during the menstruation, 

 milk may appear (Scanzoni, Gauthier). The most intensive impulse of 

 growth occurs during pregnancy. The breasts swell and toward the end 

 of pregnancy may yield colostrum on expression. There is no doubt but 

 that this impulse for growth is set free by hormones. This is shown by ob- 

 servations on the Siamese twins, Blazek; when the one became pregnant the 

 breasts of the other swelled also, and after confinement, secretion of milk 

 occurred in both (Schauta)', Grigori and M. Cristea could make the same 

 observation on parabiotic animals. For the hormone theory speaks also 

 the observation of Ribbert that transplanted mammae secrete milk after 

 birth. The ovaries are not necessary for the pregnancy-hyperplasia of 

 the mammae, as also in spite of castration undertaken in the early stages 

 of pregnancy, the development of the breasts proceeds in a normal manner, 

 and the women are able to suckle their children. Mainzer has collected 



