79 



tissue juice. 11 can also be seen thai I h e s 1 i g ii I e s t, 

 variation o I' the li y d r o g e n ion c o n c e u I i- a I i o n 

 o f t h e cull u r e ni e d i u ni result e d i n ui a r k e d c li a n- 

 gcs in the rate o I" growth ol" ti 1) I'o h I a s I s. And it 

 is interesting to notice here the fad, which has been men- 

 tioned before, Ihal the differences were mostly ot ({uanlitative 

 nature. The only morphological change of (he cells observed 

 was that, in the acid media they showed more vacuoles than 

 in the alkaline. 



Lewis and 1<' e 1 1 o n •'^'^) have investigated the intUience 

 of the hydrogen ion concentration on the growlh of fibro- 

 blasts in Locke-Lewis salt solution. They were able to 

 investigate a much wider range of different hydrogen ion 

 concentrations than I was able to do, on account of the 

 liquid media they used for the experiments; on the other 

 hand they were not able by their technique to invesligale 

 the prolongated action of various concentrations of Ihe hy- 

 drogen ions on the tissue cells as I was able to do by 

 the technique described here. They varied the hydrogen 

 ion concentration from pH 4,0 to pH 9,2. They determined 

 the hydrogen ion concentration by the method of Fel- 

 t o n i«^; of the culture media at different stages of the 

 growth of the cells. Fibroblasts cultivated in a medium wilh 

 a hydrogen ion concentration of pH 4,0 to 5,5 seldom showed 

 any growth; those in a medium of pH 5,5 exhibited growth 

 in a few instances; while those in media having a hydrogen 

 ion concentration from pH 6,0 to pH 9,0 usually showed 

 abundant growth. 



