CHAPTER XIII 



SYNTHESIS 



(With notes on the auxins and vitamins) 



* 



Putrefaction may, I conceive, be considered as a spon- 

 taneous analysis, without heat; or a subsidence and laceration 

 of the particles of bodies, by the weight of their mass, and by 

 the dilatation of the fluids they contain, but aided by the external 

 heat of the atmosphere. This spontaneous analysis disengages 

 the aqueous, oily and saline principles of which the bodies 

 consist. — Beaum6. 



In company with many foul-smelling substances, there occur 

 amongst the products of decomposition and putrefaction a 

 number of ring compounds having a pleasant odour. Some of 

 them, such as phenyl-acetic acid, have a use as perfumery 

 synthetics, but their discovery in putrescent meat and the like 

 was made long before any commercial application was found 

 for them. 



Indole-acetic acid has long been known as a product of 

 natural decomposition of protein. Pathologists have devised 

 a method of testing — the "urorosein" test — for its supposed 

 presence in urine (see p. 123). A positive result from this test 

 has been stated to be suggestive of intestinal disorder. There 

 is little doubt that indole and indole-acetic acid in nature are 

 derived from the breakdown of trytophan contained in many 

 proteins. 



It has recently been found that many ring-substituted fatty 

 acids possess remarkable powers of altering the modes of 

 growth of plants. The first of these compounds to be chemi- 

 cally identified after its growth-regulating properties had been 

 recognized was indole-acetic acid from urine. It was originally 

 called "heteroauxin" by the plant physiologists. Indole-acetic 

 acid occurs in urine much more frequently than the old uroro- 



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