TENSION FHEM'Mi-.NA OF LIVING ELEMENTS. 159 



be e\pn---ed in chemical terms. It is generally supposed that 

 nucleic acid is a more abundant constituent of the nucleus than 

 of the cytoplasm, but much evidence ha- appeared for believing 

 that iti- often present in considerable quantities in the cytoplasm. 

 l.o-l> -upposed that the segmentation of the sea urchin egg is 

 accompanied by an "autocatalytic" svntlu--i- of nucleic acid, 

 HIM -I- tin- nuclei increased in number. But Ma-in- 1 and more 

 recentlj ^hackell 2 by chemical analysis found as much nucleic 

 .11 id in the unsegmented egg or i-cell st.ro as in the Ma-tula 

 -i.i. 



I IM n i- -omc indirect evidence that increase in permeability 

 ina\ e.m-e an increased division rate of tis-ue cell-. Though 

 ii-ll Drouth may inlluence division, it is probable that permc- 

 abiliix inlliienccs growth. 



Y.iriou- "-tiniuli" cause increased proliferation of cells of the 

 -< Tinin.il layer of the skin. It is commonly known that mechani- 

 ,il -tiimili increase growth of the skin. 



I'.tinlian! 1 i.-her observed that Sudan 111. or Scharlack \\ 

 cause iinii-.i^ed proliferation of the epidermi-. \\lu-n iln d\e 

 Is inje< i< d under the skin of a rabbit tin- skin ^r<>\\ - ti.uard the 



dye. 



I m-r fi'imd that gradual increase of temperature caused a 

 ( -.in --ponding increase in proliferation of ti ne ci-ll- due io 

 incre.iM-d chemical reaction and inflammation <>t the ii--n> . 

 Hut \\hen a certain temperature was reached a Midden jump in 

 i he incre.i-e in proliferation was observed wiihoui .1 corresponding 

 iuciva-e in inflammation. This is similar to ihe plieiioineiiini 

 -ten in iinlei lili/ed eggs, where a rise in temperature l.e\nnd a 

 cei lain point causes segmentation. 



It h.i- .ilso been observed that electrical Mimulation max 

 can-e increased proliferation of tissue cell-. 



\ll of these changes (electrical, thermal, or mecliaiiic.il -limu- 

 laiion. or tn-atment with lipoid soluble .-ub-tances) cause in- 



1 /.,-it. /'.\MO/. Chem.. 1910, LXXVII.. 161. 



. eji i . n. s., XXXIX'.. 573. 



1 \Vliii-h an- practically insoluble in water but soluble in fats and lipoids and, as 

 1 II.IM- iili<i-i\t-il. -lightly in lipoid-protein combinatii'- 



4 S.-r v. I >uni;rrn u. Werner, "Das Wesen Bosartigen Gesch\\ iil-tf," I.cip/i.i;, 

 . p. 65. 



