606 ON PLANT GROWTH HORMONES 
Presumably there are also in food unknown precursors or derivatives of the 
auxins. So far we have been unable to isolate auxin-b from urine ; we 
must therefore conclude that the auxin-b ingested with the food is trans- 
: frourty elimination of auxin in urine. ; 
chiief,18% | chief meat 18: oftef meal 10 | chicef meat 10% ‘cfiefmect73% 
Se is coun: Cok ea 
“GE. : i 
| 
-% : 
-~ 
Fic. 9. 
formed in the organism into auxin-a. In this connection we may recall the 
relationship between methyl glyoxal and glycerol, and that between the 
follicular hormone and its hydrate. 
The isolation of auxin-b has of course raised many new physiological 
questions. At present I would merely mention that according to experi- 
ments dueto Dr. Albert Fischer of Copenhagen, the growth of fibro-blasts of 
trourty elimination of cuir on urgestion of various, Food stuzs. 
no food i gfzcose | starch | saladoil: egguhite | 
y 
{ ; 7 3 
100ce + (So, 125: : @oocc) : 7110, 
foe ge 9) (1259) sal (7709) 
16 milfvons of ALL aaa na 72h H 2h 
peer hoar 
Syne oof 
” 
7 
| 
| 
the heart is not accelerated when auxin-a or auxin-b is added to the nutritive 
medium of tissue cultures. So far we have obtained no indication that our 
vegetable growth hormones have also the function of animal hormones. 
Rather is it a question whether the auxins, which are so important to the 
plant, have for the animal organism the character of vitamins, or whether 
they are merely substances indifferent to the animal body. 
Finally, I would like to refer to certain experiments which are really a 
