DIGESTIVE ACTIVITY OF MESENCHYME 435 



In order to determine whether the mesenchymal syncytium 

 of the adult spleen has a power over a living heterogeneous cell, 

 only such cells can be used as give an extensive growth when 

 grafted upon the chick allantois. Rapidly growing transplant- 

 able tumors offer the most suitable material. The Ehrlich 

 mouse sarcoma and the Crocker Fund mouse sarcoma 180 were 

 chosen. In comparison with the epithelial tumors and the 

 Flexner-Jobling sarcoma of the rat, both tumors seemed to pre- 

 sent great advantages for my purpose. A study of their growth 

 in the allantois has shown them arranged in this environment in 

 the form of a labile syncytium. Their cells are highly mobile 

 and they frequently show protruding processes (fig. 1), and 

 may wander out individually into the chick mesenchyme. This 

 character sufficiently explains the diffuse growth of this tumor 

 along the periphery of the graft, and the infiltration of the 

 loose tissue of the allantois. The same property would tend to 

 effect a closer intergrowth with the splenic mesenchyme, if both 

 tissues were grafted together. Moreover, when occasionally 

 found within the lumen of an eroded vessel, the cells of these 

 tumors are seen to lose all their connections with the common 

 syncytium and to become spherical. Except for size, they are in 

 such a case extremely similar to hemoblasts, but, unlike them, 

 they never show any sign of progressive differentiation. 



The tissues for most of my present experiments were crushed 

 by forcing them through a syringe with a sieve bottom. This 

 procedure does not injure many of the cells nor even particles 

 of tissue, but it loosens the texture of the tissue and seems to 

 facilitate the access of cells and groups of cells into the allantois. 



Grafted simultaneously and in close contact, both spleen 

 and tumor tissues grew, as already shown by Stevenson. After 

 six to seven days a large growth was usually found in the region 

 of the graft, of which one part consists of splenic and the other 

 of tumor tissue. A detailed analysis of the growth of both 

 tissues at various periods was studied, especially in the region 

 where the tissues come together. This analysis is given in sec- 

 tion 4. Both tissues grew well at the periphery, except where 

 they came into contact. Contact occurs at somewhat different 



