MECHANISM OF SECRETION. 21 



lary gland in dogs ; and lie has shown that during the func- 

 tional activity of this organ, if a tube be introduced into the 

 vein, the quantity of blood which may be collected in a given 

 time is four or five times that which is discharged in the in- 

 tervals of secretion. 1 It was ascertained, also, that the venous 

 blood coming from the gland contained much less water 

 than the arterial blood ; and on comparing the quantity of 

 water lost by the blood in its passage through the gland in 

 a ghen time with the quantity discharged in the saliva, they 

 were found to exactly correspond. 11 



The differences in the quantity and the composition of 

 the blood coming from the glands during their repose and 

 their activity have an important bearing upon the mechan- 

 ism of secretion. As far as the composition is concerned, 

 these differences appear to be mainly dependent upon the 

 modifications in the circulation. When the gland is in re- 

 pose, the blood coming from it has the usual dark, venous 

 hue and contains the ordinary proportion of carbonic acid ; 

 but during secretion, when the quantity of blood passing 

 through the organ is increased, the color is nearly as bright 

 as that of arterial blood, and the proportion of carbonic acid 

 is very small. At this time, also, the blood is frequently 

 discharged from the vein pulsatim to the distance of several 

 inches. 3 The cause of this difference in color is very easily 

 understood. During the intervals of secretion, the blood is 

 sent to the gland for the purposes of nutrition and the man- 

 ufacture of the elements of the secretion. It then passes 



logiques des liquides de Vorganisme, Paris, 1859, tome ii., p. 272, et seq. ; Du 

 role des actions reflexes paralysantes dans le phenomene des secretions. Journal de 

 Vanatomie et de la physiologie, Paris, 1864, tome i., p. 507, et seq. ; Lecons sur les 

 proprietes des tissus vivants, Paris, 1866, p. 400, et seq. 



1 Unpublished lectures delivered by Bernard at the College of France in the 

 summer of 1861. 



2 Unpublished lectures, 1861 ; Journal at tanatomie et de la physiologic, 

 Paris, 1864, tome i., p. 513 ; and Lemons sur Ifs proprietes des tissits vivants, 

 Paris, 1866, p. 401. 



3 BERNARD, Liquides de Vorganisme, Paris, 1859, tome ii., p. 296. 



