52 (ii6) Society for Experimental Biology and Medicine. 



ment. The nucleated half was stained and was shown to have 

 had the mitotic figure intact. From these experiments no other 

 conclusion can be drawn than that the centrosomes, with cen- 

 trales of the enucleated fragments, were formed de novo. 



21 (67). " Structure of vaccine bodies in isolated cells," with 

 demonstrations : JAMES EWING. 



One of the few points on which all observers of vaccine bodies 

 are agreed is that these structures are extremely susceptible to 

 artificial changes. The author has for some years endeavored to 

 find a method of examination of these bodies by which artificial 

 changes could be avoided ; and this object seems to have been 

 accomplished by the very simple procedure of making Klatsch 

 preparations of corneal vaccine ulcers. 



A glass slide is cleaned with soap and water, and thoroughly 

 heated in a Bunsen flame. It is then found to be unusually adhe- 

 sive. The cornea of an anesthetized rat or rabbit, presenting a 

 vaccine ulcer at any stage, is exposed by holding back the eyelids 

 and protruding the eyeball. The cooled slide is then lightly 

 applied to the ulcer and quickly withdrawn without lateral motion. 

 The slide carries away with it an impression of the ulcer in the 

 form of isolated cells or groups of cells loosened by edema. In 

 this way ten to twenty impressions may be taken in serial order 

 and the minute ulcer may be completely excavated without sacri- 

 ficing the animal. The isolated cells dry instantly and may be 

 fixed by gentle heat, and afterward by methyl alcohol, and then 

 stained by various methods, preferably by Nocht-Romanowsky for 

 ten minutes. The vaccine bodies are then presented with a clear- 

 ness equal to that of the malarial parasite in blood spreads. 



In the Klatsch preparations stained by Nocht's method the 

 following features of the vaccine bodies appear to be demonstrated. 

 The vaccine body is a portion of the cytoreticulum, its reticular 

 structure being continuous on the one hand with the cytoreticulum 

 and on the other usually with the nuclear reticulum. The clear 

 zone surrounding the vaccine body in sections of tissue is an arti- 

 fact. The reticulum of the vaccine body takes the chromatin stain, 

 indicating that it contains chromatin, and many of the bodies are so 

 intimately connected with the nucleus, the meshes of one passing 



