WITH THE MICROSCOPE. 133 



The Lacteals may be demonstrated when filled with chyle at the 

 time of death. Their arrangement may be very satisfactorily observed 

 in the villi of a rat or mouse which has been fed upon a small 

 quantity of fatty food for some time before death. The animal 

 should be killed by suddenly dashing it on the floor. It should be 

 examined immediately or the lacteals will become emptied before 

 they are placed under the microscope. 



The alimentary canal of the mouse is well suited to the purpose 

 of microscopical investigation. The villi are large and conical, 

 and beautiful transparent injected preparations of them may be 

 made. A small piece of intestine may be injected without difficulty 

 according to the plan indicated in fig. 166, pi. XXV. After the 

 vessels have been injected, the intestine is to be slit up and small 

 pieces inverted upon the surface of glycerine containing a little 

 acetic acid (i per cent.). In this way the villi are made to stand up 

 firmly from the surface of the mucous membrane, and they 

 retain their position when the specimen is mounted permanently, 

 pi. XXXII, fig. 208. In fig. 209 villi in which the lacteals have 

 been injected are represented. 



232. Of the Movements of the Chyle. For studying the move- 

 ments of the chyle in the lacteals, a mouse, rat, or young rabbit 

 may be taken. The animal should be fed with a little lard beaten 

 up with a piece of pancreas and a small quantity of bile, so as to 

 form a soft pultaceous mass which may be strained through muslin. 

 About half an ounce, or less, of the cream-like fluid may then be 

 injected by the aid of a small syringe into a flexible catheter which 

 has been passed down the gullet into the animal's stomach. After a 

 couple of hours, the creature should be pithed, stunned, or destroyed 

 very suddenly, and a small portion of the mesentery with the 

 intestine attached withdrawn through an aperture in the abdominal 

 walls and submitted to microscopical examination with a low power. 



Organs of Circulation. 



The examination of the various textures entering into the forma- 

 tion of the circulating organs has been already referred to, but I 

 propose in this place to describe the method of examining the blood 

 corpuscles, and allude to that of investigating the phenomena of the 

 circulation during life. 



233. Blood corpuscles or globules from the human subject, are 

 represented in pi. XXXIII, fig. 212. Their general characters, and 

 especially their colour and refractive power, should be contrasted 

 with oil globules of different kinds, air bubbles, and microscopic 



