INFLUENCE OF NERVOUS SYSTEM. 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 coidd 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 
cuttino- 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. z. Anal. u. Physiol. (Eckhard), Giessen, 1855. 
4 Rohrig, quoted by Heidenhain (Hermann's " Handbuch," Bd. iv.) ; de Sinetv. 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. 
