CHEMICAL /?.hS7<S' OF (IROWTll A\D REl'Mli. 'TIT [ M I \JJ,S" 285 



transformed into the protamin t3^pe of protein (characterized by con- 

 taining hirji^e proportions of tlir ixilyamiiio-acids, such as arj^inine, 

 histidine, and lysine)/ which unite with nucleic acids to form the 

 abundant nucleoprotein of the spermatozoa and ova. Whether such a 

 transformation of proteins occurs in mannmdian cells during cell 

 multiplication cannot be stated, but certainly from some source an 

 additional supply of nucleoprotein is derived. Developing sea urchin 

 eggs synthesize great quantities of nucleoprotein,^'' even when in a 

 solution free from phosphates, and here the only available source for 

 the phosphoric acid of the nucleins would seem to be the lecithin of 

 the egg (J. Loeb). The nucleoproteins during karyokinesis undergo 

 a chemical change in that they become of a more acid type (presum- 

 ably through splitting off of part of the proteins from the nucleic 

 acid), which results in the characteristic increase in affinity for basic 

 dyes, and the increased negative charge which is easily demonstrated.® 

 This suggests the participation of an enzyme in the process of karyo- 

 kinesis, just as there seems to be in the production of pycnosis in de- 

 generating cells, but there seems to be no conclusive evidence on this 

 point. Gies " could find no enzyme in spermatozoa that incites cell 

 division in the ova of sea-urchins (Arhacia). The fertilization of 

 eggs makes them more permeable to ions,^"^ which possibly determines 

 many of the subsequent changes. 



In metaplasia we have what may be interpreted as a chemical alter- 

 ation due to mechanical stimuli, e. g., the fonnation of keratin by cells 

 that ordinarily do not do so ; the deposition of calcium salts and oste- 

 oid transformation of connective tissues in rider's bone, etc. That 

 such is the case, however, cannot be positively stated from the evidence 

 at hand. 



CHEMICAL BASIS OF GROWTH AND REPAIR. '"VITAMINES" i- 



We do not know just what substances are necessary to maintain 

 individual cells in normal conditions, what are needed to stimulate 

 them to multiplication, or what elements they require to permit them 

 to multiply, but it has been learned that certain definite materials are 

 required by the organism as a whole. It is not sufficient that a given 

 number of calories, with a certain quantity of proteins, carbohy- 

 drates, fats and salts be supplied ; it is essential that certain specific 

 constituents be provided among these foodstuffs. The proteins must 



7 Concerning protamins, see resume bv Kossel, Biocliem. Ceiitr.. 1000 C5), 1 

 and 33. 



Ta Xot accepted bv I^Tasing, Zcit. plivsidl. Clieiii.. 1010 (fi7), IHl. 



'^See Gallardo, Arch. Entwickl. Organ., 1000 (2S), 12.i: Pentiinalli, U>i<1.. 1012 

 (34). 444. 



oAmer. .Tour. Phvsiol.. 1001 ffi). .54. 



11 See IMcClendon', Carnegie Inst. Publ.. 1014, Xo. 1S3. 



12 See Mendel, "Nutrition and Growth," Harvev Society Lectures. 1014- I.t: 

 Amer. Jour. Med. Sci., 1917 (153), 1. 



