SECRETION. 263 



Steinhaus the nucleus nearest the lumen undergoes a fattv metamorphosis. 

 According to the same author the granular material in the cytoplasm also 

 undergoes a visible change; the granules, which in the resting cell are 

 spherical, elongate during the stage of activity to threads thai take on a 

 spirochaeta-like form. The acme of this phase of development is reached by 

 the solution or disintegration of a portion of the end of the cell, the frag- 

 ments being discharged into the lumen of the alveolus. The debris of this 

 disintegrated portion of the cell helps to form the secretion ; part of it goes 

 into solution to form, probably, the albuminous and carbohydrate constituents, 

 while the fat-droplets are set free to form the milk-fat. Apparently the basal 

 portion of the cell regenerates its cytoplasm and thus continues to form oew 

 material for the secretion. In some cases, however, the whole cell seems to 

 undergo dissolution, and its place is taken by a new cell formed by karvo- 

 kinetic division of one of the neighboring epithelial cells. The origin of the 

 peculiar colostrum corpuscles found in the milk during the first few days 

 of its secretion has been explained differently by different observers. Heid- 

 enhain traces them to certain epithelial cells of the alveoli which at this 

 time become rounded, develop numerous fat-droplets, and are finally dis- 

 charged bodily into the lumen, although he was not able to actually trace 

 the intermediate steps in the process. Steinhaus, on the contrary, thinks 

 that these corpuscles are derived from the wandering cells of the connective 

 tissue (Mastzellen) which at the beginning of lactation are very numerous, 

 but seem to undergo fatty degeneration and elimination in the secretion of 

 the newly active gland. 



Control of the Secretion by the Nervous System. — There are indica- 

 tions that the secretion of the mammary glands is under the control, to some 

 extent at least, of the central nervous system. For instance, in women during 

 the period of lactation cases have been recorded in which the secretion was 

 altered or perhaps entirely suppressed by strong emotions, by an epileptic attack, 

 etc. This indication has not received satisfactory confirmation from the side 

 of experimental physiology. Eckhard 1 found that section of the main nerve- 

 trunk supplying the gland in goats, the external spermatic, caused no dif- 

 ference in the quantity or quality of the secretion. Rohrig 2 obtained more 

 positive results, inasmuch as he found that some of the branches of the exter- 

 nal spermatic supply vaso-motor fibres to the blood-vessels of the gland and 

 influence the secretion of milk by controlling the local blood-How in the 

 gland. Section of the inferior branch of this nerve, for example, gave in- 

 creased secretion, while stimulation caused diminished secretion, as in the 

 case of the vaso-constrictor fibres to the kidney. These results have qoI been 

 confirmed by others — in fact, they have been subjected to adverse criticism — 

 and they cannot, therefore, be accepted unhesitatingly. 



Mironow 1 reports a Dumber of interesting experiments made upon goats. 



1 See Heidenhain : Hermawnfs Handbuch der Physiologic, Bd. v. Thl. 1. 8. 392. 



2 Virr/imi-'s Archir fur pathologiache Anatomie, etc., 1876, Bd. 67, 8. 119. 



3 Archives <lrx Science* hiii/iii/it/iics, St. Petersburg, IS'.M, t. iii. p. :'.',.",. 



