, ZYMOLOGY FERMENTS AND FERMENTATIONS 215 



exceedingly liable to precipitation and inactivation. The greater sensitive- 

 ness to temperatures of true ferments being probably due to the associated 

 salts, for it is known that the sensitiveness to heat, of colloidal solutions, 

 increases with the amount of impurities added. It is known that the com- 

 paratively purer ferments are more stable and less sensitive to heat than are 

 those which are comparatively impure. This is a fact well known to manu- 

 facturers of such commercial ferments as pepsin, pancreatin, etc. The 

 catalyzing activities of metals (finely divided and as sols) is however not 

 limited to processes of chemical decomposition. For example, in the 

 commercial synthetization of ammonia from free nitrogen and hydrogen, 

 acted upon by the electric spark and subjected to pressure (175 atmos- 

 pheres) and heat (500 C.), the rate of ammonia production is very materi- 

 ally increased in the presence of certain metals in. the powdered form, as 

 uranium osmium, mercury, iron and platinum. The metals remain un- 

 changed and exert their catalytic action for an indefinite period of time. 

 It is also known that the catalytic power of different metals varies greatly. 

 In the ammonia production referred to, osmium is far more active than 

 uranium or iron. In practice the metals giving a' maximum yield in 

 proportion to their cost and accessibility, are used, rather than the more 

 active but comparatively rare and expensive metals. 



There are many phenomena which are as yet unexplained and which 

 present many of the characteristics of fermentations. It is probable that 

 many of the life processes arje controlled and directed by enzymes. The 

 influence of the male reproductive cell is of such a nature. An enzyme-like 

 substance perhaps acts upon the ovum inducing indefinite septation and 

 growth, resulting in a new individual. It would appear that the growth 

 of the body, of its tissues and its organs, is directed by enzyme-like stimuli. 



These growth enzymes apparently occupy certain positions in the 

 body and by their oxidizing influence produce or direct the various 

 complex chemical changes (assimilation) which result in the formation 

 and growth of the tissues and organs. Normally these growth ferments 

 are active in such a manner (regulated and inhibited) as to give rise 

 to plants and animals which we designate as normal; but occasionally 

 there is a disturbance or displacement in these enzymes and growth 

 irregularities are the result, such as local and general dwarfism and 

 giantism, atavistic marks and anomalies, supernumerary fingers and 

 toes, duplication of parts, twins, etc., etc. We may assume that the 

 geotropic position of roots and stems and the horizontal position of 

 branches of plants, is controlled by enzymes. Occasionally the nor- 

 mal positions are reversed or changed. It is not uncommon to find large 

 trees, especially in virgin forests, with all branches but one, in the usual 

 or normal position, the exceptional branch having assumed the vertical 



