145 
Extracts from British and Foreign Journals. 
COLOUR 0-F THE BLOOD IN THE RENAL VEINS. 
By M. Claude Bernard. 
Dr. Hargitt has communicated the following in a letter 
addressed to the editor of the Lancet . 
Scientific observers are now 7 agreed on the point that the 
blood in the renal veins is red in colour like unto arterial, 
and it is but lately that M. Claude Bernard suggested that 
this peculiar condition of the venous blood might be owing 
to a removal from the blood by the secreting organ of 
a portion of its watery element. In order to determine 
this point, he directed his attention to the condition of 
the venous blood issuing from another organ, whose func- 
tion, like the former, consisted in the removal of a watery 
element from the blood. This organ was the large sub- 
maxillary gland, and to his surprise, at first, he found that at 
certain periods the blood in the small sub-maxillary vein was 
black, at other times red ; that during the process of salivary 
secretion the venous blood w 7 as red, and that as the gland 
reposed the blood assumed its black colour. 
The experiment to determine this was performed on a dog. 
He dissected carefully the sub-maxillary region, exposing the 
gland, with its artery, vein, nerve, and duct. On exposure 
of these parts, the blood in the small sub- maxillary vein was 
black ; the gland W'as reposing, there being no salivary secre- 
tion. A sponge dipped in vinegar w as now applied to the 
tongue, thus inducing rapid salivary secretion, and at the 
same moment might be observed the gradual change in the 
colour of the blood in the sub-maxillary vein from black to 
red. As the flow 7 of saliva ceased, the blood gradually reas- 
sumed its dark aspect. The small nerve going to the gland 
w r as now irritated by the forceps ; secretion recommenced, 
and again were witnessed the same changes in the colour of 
the blood. The nerve being now divided stopped the secre- 
tion, and the venous blood again became black. Finally, 
the divided nerve w r as galvanized ; this induced another flow 
of saliva ; the small vein w as at this moment opened, and 
the gradual change in colour of the blood from black to 
red or scarlet was visible to all as the blood flowed into glass 
tubes. 
From this experiment, only lately performed, M. Bernard 
comes to the conclusion, that the blood in the renal veins, as 
xxxi. 20 
