Amoeboid cells in intestinal absorption. io 



the amoeboid cells of the mesoblast or mesoderm are in all 

 likeKliood originally derived in part at least from those of 

 . the liypoblast or entoderm, wMch are tbemselves the repre- 

 sentatives of the epithelium cells of the intestinal tract, so 

 that the derivation of leucocjrtes from these would be no more 

 than a retention during- life for a specialized purpose (that 

 namely of promoting absorption) of a property possessed by 

 them in the embryo. Nor does the purpose in question seem 

 altogether confined to post-embryonic life, for it is stated 

 by Kollmann*) to occur in the embryos of oviparous verte- 

 brates, where the nutritive material derived from the yolk, 

 after having been absorbed into the larg-e columnar cells of 

 the entoderm and having there undergone digestion and assi- 

 milation, is according to that author conveyed in part at 

 least from these cells into the mesoderm by migratory cells, 

 wliich are themselves derived from the entoderm-cells. These 

 considerations should lead one not too hastily to exclude the 

 possibility of the leucocytes, which are found between the 

 columnar epithelium-cells of the intestine and which appear to 

 be concerned in the transference of absorbed materials from 

 those cells into the lacteals, being derived from the epithe- 

 lium-cells themselves as weil as by miütiplication of those 

 leucocytes which are already present. Careful investigation will 

 however be necessary before this point, which is one of the 

 highest importance both morphologically and physiologically, 

 can be satisfactorily cleared up. 



However derived, there is little doubt that the leucocytes may 

 be nourished and grow at the expense of absorbed nutriment and 

 that within their protoplasm a process of assimilation may occur, 

 leading to the formation of organic substances peculiar to the animal 

 body from the digested matters of the food. Such substances, includ- 

 ing those of which their protoplasm itself is composed, are set free 

 on the disintegration of the corpuscles within the lacteals, and in 



Kollmann, Intracelluläre Verdauung in der Keimhaut. Recueü zoologique 



suisse, No. 2, 1884. 



