INFL UENCE OF NER VO US S YSTEM. 663 



the first two or three days after parturition, and which are sometimes 

 even to be detected during full lactation. These colostrum corpuscles are 

 seen to be amoeboid when examined on the warm stage, and are, there is 

 little doubt, leucocytes which have wandered out from the interstitial 

 connective tissue of the gland into the lumen of the alveoli. Some have 

 regarded them as detached epithelial cells, and look upon their presence 

 in the alveoli and in the milk as evidence of the normal occurrence of 

 such detachment during active secretion (see p. 666) ; but it must be 

 admitted that they have neither the appearance of epithelial cells, nor 

 do the latter tend to exhibit any such amoeboid movement as is shown 

 by the colostrum corpuscles. These corpuscles, in fact, seem to be 

 rather analogous to the salivary corpuscles (see p. 344), and to be 

 similarly derived from emigrated leucocytes. 



During the period of lactation the alveoli secrete milk, not only 

 whilst the gland is being drawn by the process of sucking or milking, 

 but in the intervals of such processes, so that the milk accumulates 

 both in the alveoli and in the ducts. The latter are provided with (in 

 some animals very considerable) dilatations, which serve as reservoirs 

 for the accumulated secretion, and it is mainly this accumulated milk 

 which is poured out during the milking. No doubt fresh milk becomes 

 secreted to take the place of that which is drawn away ; and as a con- 

 comitant to this fresh secretion, there is a considerable flush of blood to 

 the gland. It has been calculated that the udders of a cow could not 

 contain all the milk which is sometimes drawn at one milking, so that 

 secretion must be proceeding at the same time. Moreover, the later 

 drawn portions of milk contain more solids in proportion than those 

 first drawn. 1 Lehmann 2 injected sulphindigotate of soda solution 

 into a vein of a milch goat, and at once had the animal milked. 

 No blue appeared in the milk until the udders were almost com- 

 pletely drawn, when there was a slight tinge. On milking the animal 

 again, after the lapse of an hour or an hour and a half, the milk which 

 had collected in the udder was completely blue. 



Influence of the nervous system on the secretion of milk. 

 Although it is a matter of common experience that the quantity and 

 quality of the milk is in women materially influenced by the condition 

 of the nervous system, the results of experiments upon animals have 

 furnished evidence on this subject which is either entirely negative, or 

 at most of a somewhat conflicting nature. Eckhard, 3 who was the first 

 to attempt to obtain such evidence, found no marked difference in the 

 milk either in quantity or quality from the udder of a goat, the nerves 

 (branches of external spermatic) passing to which had been cut, as 

 compared with the milk drawn from the other side, the nerves of which 

 were intact. His observations have been repeated by others, 4 with 

 contradictory results, some having obtained an increase of secretion on 

 cutting the nerves, others a diminution. But even if an increase is 

 obtained, it has not been determined whether this is due to the 

 alteration in the vascular supply to the gland rather than to a direct 

 effect upon the gland-cells, such as is obtained in the case of the 



1 For references, see Heidenhain, Hermann's "Handbuch," Bd. iv. 



2 Die landwirthsch. Versucht, 1887, Bd. xxiii. S. 473. 



3 Beitr. s. Anat. u. PhysioL (Eckhard), Giessen, 1855. 



4 Rohrig, quoted by Heidenhain (Hermann's "Handbuch," Bd. iv.) ; de Sine'ty, Gaz. 

 med. de Paris, 1879, p. 593 ; Valentowicz, Centralbl. f. PhysioL, Leipzig u. Wien, 1888, 

 Bd. ii. S. 71 ; Mironow, Arch, de sc. biol., St. Petersbourg, 1895, tome iii. p. 453. 



