180 THE AMERICAN MONTHLY [June, 



latter, of course, are to be looked upon as the trunks, of 

 whicli the former are the branches. 



I would call especial attention to these structures and 

 their arrangement, because physiologists seem entirely 

 to ignore them. In several of the latest text-books, at 

 least, I do not even find them mentioned, and thus a dis- 

 cussion of their function at this time cannot be ex- 

 pected ; and yet the nerve supply of this system is as 

 large as that of the motor nerves of the muscle. For if 

 we take into consideration the size of the cells forming 

 the capillary wall, and compare this with that of the 

 muscle-fibre, we see that the nerve supply of the capillary 

 is immeasurably larger than that of the muscle-fibre 

 and we are justified in assuming that we have to deal 

 here with a very delicate and important physiological 

 apparatus. We see, further, that these nerves are branches 

 of the sympathetic nerve; that they have centrifugal 

 function ; that through their activities the cells of the 

 capillary wall are stimulated to execute certain 

 actions as the muscle is stimulated to contact by its 

 nerve. Experimental pathology further shows us what 

 sort of activity the capillary wall is engaged in. If it is 

 irritated we see that a larger quantity of serum passes 

 through its walls, that the irrigation stream is increased. 



If we now take together the results of experiment and 

 the histological facts, it seems to be a permissible hy- 

 pothesis to assume that through the influence of these 

 nerves the flow of the lymph current from the blood to 

 the tissues can be increased — or rather regulated, so that 

 while, e. g., the nerve-fibre {A) stimulates the muscle- 

 fibre, causing it to contract, the nerve-fibre {B) would 

 cause the cells of the capillary wall to allow a larger 

 amount of lymph to be poured over the contracting mus- 

 cle. It is by no means necessary to consider this action of 

 the capillary cells as one of contraction but rather some- 



