VARIATIONS IN COLOUR Of THE VENOUS BLOOD. 143 
panico-lingual nerve acts with energy, the venous blood of 
the sub-maxillary gland appears red, whereas it becomes 
black whenever this nervous twig does not act, or its action 
ceases to preponderate. 2. The venous blood of the sub¬ 
maxillary gland is black whenever the sympathetic nerve 
acts, and it is the darker in colour as this nerve exerts a more 
energetic action. The mechanical conditions of the capillary 
circulation of the gland, determined by these two sets of 
nerves, are exactly inverse. When the tympanico-lingual is 
excited, the rapidity of the circulation is considerably in¬ 
creased ; when the sympathetic acts, the rapidity of the circu¬ 
lation diminishes. In one case it was found that during the 
repose of the gland, sixty-five seconds were needed to collect 
five cubic centimetres of blood from the vein of the gland; 
but when the tympanico-lingual was excited by galvanism 
it needed only five seconds to procure the same quantity, and 
if the action of the sympathetic nerve is sufficiently energetic 
the flow of blood from the vein may be completely stopped, 
again to appear when the excitement of the sympathetic 
ceases, and to be afresh accelerated if the tympanico-lingual 
is again acted upon. The reason for this is, that the tym¬ 
panico-lingual nerve increases the calibre of the capillary 
vessels; the sympathetic decreases it. The sympathetic is 
the constrictor, the tympanico-lingual the dilator, of the 
blood-vessels of the gland, and thus during the action of the 
former the contact between the blood and the elements of the 
gland is prolonged, the chemical phenomena which result 
from the organic exchange have time to take place, and the 
venous blood becomes very black; but, on the contrary, 
during the action of the tympanico-lingual the course of the 
blood through the gland is very rapid, the modifications of 
venosity are differently accomplished, and the blood flows 
from the vein very ruddy, and preserving its arterial appear¬ 
ance. Owing to the influence of these two sets of nerves, the 
sub-maxillary gland enjoys in reality an individual circula¬ 
tion, which in its variations is independent of the general cir¬ 
culation ; and this is probably true with reference to all the 
organs of the economy. The nervous system which animates 
each capillary system, each organic tissue, regulates the 
course of the blood with reference to the peculiar chemical 
or functional state of the organ. M. Bernard promises a 
further communication on the actual chemical modication of 
the blood, produced by the above physiological conditions.— 
Medical Times and Gazette . 
