106 VERA DANCHAKOFF AND S. M. SEIDLIN. 



intensive proliferation of these cells is observed in the hemopoietic 

 tissue of this organ. No decrease of small lymphocytes is brought 

 about by the excessive withdrawal of these elements, but, on the 

 contrary, the lymphatic elements seem to become even more nu- 

 merous and mitoses particularly frequent. 



The shifting of numerous small lymphocytes to the injected 

 region produces evidently a stimulating effect upon the hemo- 

 poietic tissue of the kidney, similarly to a bleeding of the animal. 

 In this case however the white blood corpuscles only are carried 

 away in greater numbers and those remaining proliferate more in- 

 tensively. A proliferation of small lymphocytes in the lymphatic 

 tissue has been found under various conditions, after administra- 

 tion of small doses of X-ray in particular. A direct stimulating 

 effect upon the lymphatic tissue was attributed to the action of 

 the X-rays. It is, however, questionable whether this stimulating 

 effect might not prove to be a secondary phenomenon due either 

 to destruction or to an intensive shifting of the small lymphocytes 

 from the region of their origin. 



A third category of wandering cells may be recognized around 

 the injected material. They are mobilized mesenchymal cells, in 

 the early stages very few in number and never numerous. They 

 are large, have a rather basophilic cytoplasm, and their nuclei fre- 

 quently exhibit nucleoli. They have been already mentioned and 

 their first appearance was ascribed rather to the direct effect of the 

 injury than to the presence of injected masses. At the end of the 

 first da)- after injection a curious activity is observable in the 

 mesenchymal cells which form under the basal membrane a prac- 

 tically uninterrupted layer. These cells, normally flattened against 

 the surface of the basal membrane and in sections appearing fusi- 

 form in shape, are now seen to separate from the basal membrane 

 and to protrude their processes in the direction of the injected 

 material. They leave their original places and are found among 

 other wandering cells. Easily recognizable at first they gradually 

 undergo a series of changes in the same direction as described for 

 the small lymphocytes, and at a later stage these cells are no longer 

 recognizable as such. 



In order to make a complete picture of the wandering cells in 

 the region of the injection, eosinophilic leucocytes should be men- 



