Resorption of the formed elements 69 



that normal blood serum, when injected under the skin of animals, 

 does not provoke albuminuria at all, or at least produces it in a very 

 insignificant and transitory degree. 



The mechanism by which the organism modifies these nutritive 

 substances, introduced by a channel other than the digestive canal, is 

 not as yet sufficiently known; and is therefore not easy to define. 

 But we know, very definitely, that each injection of serum, whether 

 of white of egg, milk or fatty matter, is followed by a rather consider- 

 able aseptic inflammation at the point at which these substances are 

 introduced. We might conclude from this that the organism digests 

 the food substances outside the gastro-intestinal canal, by means of 

 an inflammatory reaction. In order to determine more exactly the 

 phenomena that appear under these conditions, it may be useful to 

 consider first, not the fluid substances but the solid elements that are 

 introduced into the tissues and cavities. 



Let us begin with the lower animals in which the anatomical 

 organisation and all the functions are of a much more simple 

 character than they are in the Vertebrata. In my Comparative 

 Pathology of Inflammation (Lecture IV) I have directed some 

 attention to the digestion of the Sponges. 



The nutritive substances — small organisms — whether they may 

 have entered by the small openings, so numerous on the surface of 

 Sponges, or have been introduced through a rent in the body wall, 

 undergo the same fate. They are seized by vibratile or amoeboid 

 cells which ingest the food and digest it by an intracellular digestion. 

 These two kinds of cells, which come under the category of Phagocytes, 

 have a great resemblance to one another, and we may say that 

 digestion and resorption are two very closely related phenomena. 



When we examine somewhat higher Invertebrata, such as the 

 Medusae or certain other Coelenterates, we can still trace a close 

 analogy between the true digestion of the food that goes on within 

 the epithelial cells of the entoderm and the resorption of certain 

 foreign bodies which make their way by an extra-buccal channel into 

 the intermediary tissue. Here these bodies are surrounded by 

 amoeboid cells which fulfil their function as phagocytes by ingesting [75] 

 and digesting the substances that have come from outside. 



It is, here, unnecessary to go over the whole gamut of the 

 perfecting of the organisation of the Invertebrata, in its relation 

 to the resorption of foreign bodies, especially as it has already 

 been treated in my Lectures on Inflammation. Let us choose 



