f 



THE PARENTERAL INTRODUCTION OF PROTEINS 355 



When tubes are used for the introduction of the egg-white 

 it is possible that a small amount of the material may be 

 introduced through some slight wound or abrasion in the 

 mucous membrane. Sensitization might be induced in 

 this way, but it is hardly conceivable that subsequently 

 enough would be introduced in this way to kill the animal. 

 It seems, therefore, that we must conclude that in forced 

 feeding, at least, unbroken egg-white may be absorbed from 

 the alimentary canal of the rabbit. It must be understood, 

 however, that apart from any injury to the mucous mem- 

 brane, the conditions of forced feeding are not exactly the 

 same as those in natural feeding. Celler and Hamburger 

 have called attention to this point. By continued tube- 

 feeding of rabbits with the serum and blood of the ox, in 

 only one instance did they obtain a precipitin for the serum, 

 and an hemolysin for the corpuscles, while they found 

 that rabbits after fasting took the serum and blood willingly 

 when mixed with milk, and in none of these was there any 

 evidence of absorption without digestion. They admit the 

 possibility of wounding the mucous membrane with the 

 tube, or of carrying the material through the tube into 

 the intestine, but they are inclined to the opinion that in 

 the unnatural tube feeding the digestive secretions are not 

 poured out so freely or are less effective than in natural 

 feeding. This is in accord with the findings of Pawlow, 

 who holds that desire for food is an important factor in 

 securing thorough digestion. 



With this brief and imperfect review of the literature of 

 the subject, we turn to our own experimental work. Our 

 method is to inject egg-white into the animals and test for 

 its presence in the blood and extracts of tissue by sensitizing 

 guinea-pigs, having first demonstrated that the blood of 

 the rabbit and extracts from its tissue do not sensitize 

 guinea-pigs to egg-white. The details of the method will 

 be developed in the report of the experiments. Our findings 

 are as follows: 



1. Egg-white injected into the stomach of a rabbit may 

 be in part absorbed unchanged. 



