1885.] 



and the Transference of Food Materials. 



HI 



place of those which have passed into the lacteal. With regard to 

 this, it may safely be affirmed that they are continually undergoing 

 multiplication by division. No one has, so far as I am aware, ever 

 doubted that the lymph- corpuscles are thus capable of renewal, 

 although it has been generally believed that their mode of division is 

 direct, i.e., unaccompanied by those peculiar changes in the nucleus 

 which have been termed karyokinetic or karyomitoic. This has, 

 however, been settled by Fleming, who has shown that the cells of 

 lymphoid tissue multiply abundantly by karyomitosis. This multipli- 

 cation by divisiou will apply to the leucocytes which lie between 

 the epithelium-cells as well as to those in the mucous membrane 

 proper. It is doubtful whether there is any addition caused by 

 emigration of white corpuscles from the blood-vessels ; certainly it 

 is not by any means considerable. 



It is a most important question whether any amoeboid cells are 

 produced by division of the columnar epithelium- cells. That these 

 cells do divide is certain ; in confirmation of other observers I have 

 seen abundant evidence of the occurence of karyomitoic figures in 

 them ; but I am not yet able to say what is the result of such division, 

 although I am strongly disposed to think that they may give origin to 

 amoeboid cells. Several instances can be cited of the origin of meso- 

 blastic amoeboid cells from hypoblastic epithelial cells in the embryo, 

 which seem to favour this view. 



Taking for granted that the leucocytes multiply by division, the 

 newly produced daughter cells will naturally be relatively small with 

 scanty protoplasm. Being freely supplied with nutrient material 

 during the absorption of aliment, either directly from the intestine 

 or indirectly from the columnar epithelium-cells (which are probably 

 the primary ageuts in effecting absorption from the intestinal cavity), 

 their protoplasm probably in part assimilates, and in part stores up 

 this material and rapidly grows. Wandering now towards the centre 

 of the villus (urged it may be by the stream of fluid which is passing 

 at this time in that direction) the cells enter the lacteal, and there 

 become dissolved, and again set free not only the proteid matters 

 which they have assimilated and converted into protoplasm, but also 

 all other material, whether in the form of definite particles or not r 

 which may have been taken up in addition and carried by them into 

 the lymphatic vessel. 



The preparations upon which the observations and inferences which 

 are here briefly recorded are based have been made chiefly from 

 mammals, especially from the rat, in which the shape of the villi and 

 the size of their lacteals render it relatively easy to obtain successful 

 sections. Many, however, are from the frog, in which the facts can 

 be very clearly made out on account of the size of the elements, and 

 in which also the comparative slowness of the process of absorption 



