460 Growth of Tissue in Autogenous and Homogenous Plasma. 





Animal A. 



Animal B. 



Plasma A. 

 Autogenous. 



Plasma B. 

 Homogenous. 



Plasma A. 

 Autogenous. 



Plasma B. 

 Homogenous. 





o 

















100 per cent. 







100 per cent. 







Fresh 



50 







64 







Kidney. 



Of this tissue 96 cultures were made. The experiments were all carried 

 out hy the method of cross growth, which made all the requisite points clear. 

 One such experiment may be quoted as an example. 



Experiment 13. — Plasmata were collected in a manner similar to that used 

 in Experiments 5 and 12. The plasmata were respectively eight days old, 

 three days old, and fresh. In the eight-day-old plasma, as usual, no growth 

 took place. In the case of the three-day-old plasmata the kidney of 

 animal A grew well in the plasma of animal B but not at all in the plasma of 

 animal A. The kidney of animal B also grew well in the plasma of animal B 

 and not at all in the plasma of animal A. With the fresh plasmata growth 

 occurred in the case of both tissues in both plasmata, that in plasma B being 

 rather the better. Growth was in all eases less than that in the three-day-old 

 plasma of animal B. 



The results of the kidney cultures supported therefore those obtained with 

 testicle and thyroid. 



Summary. 



1. The extent of growth of tissues in vitro is not dependent upon any 

 quality of the cells themselves. 



2. The extent of growth varies directly with the character of the plasma. 



3. The variation in the plasma does not depend upon whether it is 

 autogenous or homogenous but upon some cause at present unknown. 



4. Fresh plasmata appear to contain substances, inhibitory and stimulating, 

 to the growth of cells, the latter being in excess. 



5. The inhibitory substance is lessened, or the stimulating substance is 

 increased, by freezing the plasma for one to three days. 



6. The stimulating substance is destroyed after the plasma has been frozen 

 for six to eight days. 



