LACTATION 609 



system. There is now, however, abundant evidence that such is 

 not the case. This is shown, for example, by the experiment 

 performed by Uoltz and Ewalcl, 1 which has already been referred to 

 in considering the factors concerned in parturition. The lurnbo-sacral 

 part of the spinal cord was completely exsected in a pregnant bitch, 

 so that all possible connection between the mammary glands and 

 pelvic organs through the nervous system was destroyed. Pregnancy 

 was accompanied as usual by mammary development, and after 

 parturition, lactation occurred normally. Kouth's case, 2 in which 

 normal lactation- took place in a woman with complete paraplegia 

 below the level of the sixth dorsal vertebra, has also been referred to 

 (p. 571). Moreover, it has been shown by Eckhard 3 that after 

 complete severance of the nerves (branches of the external spermatic) 

 passing to the mammary gland, the activity of the latter, and 

 consequently the supply of milk, are in no way affected. 4 



Further evidence in support of the conclusion that the connection 

 between mammary and foetal growth is not nervous in character is 

 supplied by those experiments in which portions of gland were 

 successfully transplanted to abnormal positions in the body. Thus 

 in an experiment on a guinea-pig Ribbert 5 grafted mammary tissue 

 from the normal position to the neighbourhood of one of the ears. 



1 See pp. 514 and 571. 



2 Routh, "Parturition during Paraplegia, with Cases," 7V<o<.<. ul,gt,-t. ., 

 vol. xxxix., 1897. 



3 Eckhard, Beitn'i;/'- WOT .\nat. . !'/>;/.<., vol. i., (JiVssen, 1855. 



4 Eckhard's experiments have been repeated by others with somewhat 

 contradictory results (see Basch, foe. fit.); Iiohrig (" K.\]M imentelle Unter- 

 suchungen iiber die Physiologic der Milchabsoiiderung," lY/v//w'x . I //, Y, 

 vol. Ixvii., 1876) found that the external spermatic nerve contained vaso- 

 motor fibres for the vessels of the mammary gland, and that these affected its 

 secretory activity by controlling the blood supply. Mironow (" De 1'Influence 

 du Systeme Nerveux des Glandes Mammaires, 7 ' .!///. d,'s Seuitoet ///<>/. / 

 St. Petersboury, vol. Hi., 1894) states that artificial stimulation causes a reduction 

 in the quantity of secretion. He states further that whereas section of the 

 external spermatic on one side has no effect on the secretion, section on both 

 sides diminishes it, but that the diminution only comes on gradually after a 

 number of days. After complete severance of all the nerves in pregnant 

 animals the glands may continue to grow and yield milk after parturition. 

 Basch (lot: tit.) states that extirpation of the cteliac ganglion or transect inn of 

 the spermatic nerve does not inhibit the secretory process, but increases the 

 number of colostrum corpuscles. There is abundant evidence of a general 

 kind that the central nervous system in some way exerts an influence on the 

 mammary gland. Thus the effects of nervous shock in altering or inhibiting 

 milk secretion in women are well known. Moreover, the occurrence of uterine 

 contractions on putting the child to the l>ri-a-<t. and so stimulating the nipples, 

 is evidence of a nervous connection. It would si-cm jnohable, therefore, that 

 though the mammary gland is essentially an automatic organ, the connection 

 of which with the generative organs is through the vascular i-ather than the 

 nervous system, yet it is under the regulating control of the latter by means 

 of secretory or vasomotor fibres. 



6 Ribbert, "Ueber Transplantation von Ovarium, Hoden und Mamma," 

 Arch.f. Entwick.-M-'<-li<niik, vol. vii., 



20 



