THE CAPILLARY CIRCULATION 95 



pins over the slot. There is a large lymph sac in the organ : this 

 is next distended by Ringer's solution with the aid of a hypodermic 

 syringe. The mucous membrane which is now uppermost is of some 

 thickness ; it is to be slit up longitudinally with fine scissors, and pinned 

 to either side, any escaped blood being got rid of by rinsing with Ringer. 

 The delicate internal structures of the tongue are thereby exposed 

 (muscle-fibres, connective tissue, and blood-vessels), and can be examined 

 in detail with a high power of the microscope after covering with a 

 light cover-glass. 



6. In the mesentery of small mammals such as rats and mice. The 

 method is generally similar to that used for the frog-mesentery, but 

 ansesthetisation must be produced by drugs such as urethrane or chloral 

 administered either enterically or hypodermically, and special measures 

 are necessary to keep the exposed mesentery warm and moist whilst 

 under observation. 



