APPLICATIONS OF RESULTS OF RESEARCHES. 



365 



implements to carry out operations that are essential 

 to their existence, and such enzymes are modifiable in 

 quantity and quality in accordance with changes in 

 internal and external conditions. The nature of both 

 reactions and products of enzymic action depends upon 

 the constitution and composition of the physico-chemi- 

 cal mechanism of which the enzyme is an integral part. 

 Whether or not at each step of serial reactions a portion 

 of pre-existing enzyme is merely modified or a new 

 enzyme is formed which constitutes an essential part 

 of the particular phase of the reactions is not known, 

 but that one or the other occurs is apparently without 

 question. It has long been established that some of the 

 lower organisms, such as the yeast plant, have the prop- 

 erty of modifying the characters of the enzymes pro- 

 duced in relation to varying conditions; recent studies 

 of the animal organism show that the same phenomenon 

 occurs in both tissues and blood ; and our knowledge 

 of the processes concerned in the catabolism and ana- 

 bolism of complex substances, such as starch, is fully in 

 support of such a conception. In other words, as each 

 step of development is reached the alterations which 

 occur in the physico-chemical mechanism absolutely 

 automatically predetermine the characters of the changes 

 of the next succeeding step, and so on to the end. Hence 

 it follows that the peculiarities of any given physico- 

 chemical mechanism predetermine the characters of the 

 phenomena which ensue under given conditions. 



An illustration of the probable modtts opcrandi of 

 such a mechanism is found in the phenomena of the 

 synthesis and analysis of starch : During the production 

 of starch through the agency of the chloroplast or leuco- 

 plast we conceive that there are instituted a predeter- 

 mined, orderly, independent and interdependent series 

 of reactions, the first of which is manifested in an inter- 

 action between water and carbon dioxide through the 

 agency of an enzyme in the form of an oxidase to form 

 formaldehyde. During this process there is formed an- 

 other enzyme, which tentatively may be designated an 

 aldehydase, that reacts with formaldehyde and by poly- 

 merization and condensation of six molecules gives rise 

 to a simple sugar, such as dextrose. At the same time 

 another enzyme appears in the form of maltase, which, 

 reacting with the dextrose causes the formation of mal- 

 tose, during which reaction another enzyme, a dex- 

 trinase, is produced which reacts with the maltose to 

 yield dextrin. Going on with this reaction, another 

 enzyme which may lie designated an amylase appears, 

 which, reacting with the dextrin, forms soluble starch. 

 During this stage there arises another enzyme, a coagu- 

 lase, which converts the starch from the soluble to the 

 insoluble form or ordinary starch. At this stage the 

 series of reactions have reached their end because a 

 state of physico-chemical equilibrium has become estab- 

 lished, the ultimate purpose of the processes being 

 attained, that is, a form of pabulum of extremely high 

 nutritive value and of extremely low molecular pressure, 

 even in soluble form, so that it may entirely and rapidly 

 disappear without disturbance of physico-chemical equi- 

 librium in the starch-bearing cells. The mechanism con- 

 cerned in starch-formation is without doubt paralleled 

 in the synthesis of proteins, fats, and other complex- 

 organic substances, and it is but a step from the indi- 

 vidual serial processes concerned in the formation of I 



each of these substances to associated processes whereby 

 there are formed and combined the various substances 

 that constitute the organic structural components of 

 protoplasm. Moreover, such serial processes are rever- 

 sible at any stage, and so simple a modification as a 

 change in the percentage of water may, as in the maltose- 

 dextrose-glucase reaction, cause a synthetic change. 



In vitro in both synthetic and analytic processes like 

 those which constitute serial steps in the building up 

 and breaking down of starch, protein, fat, and other 

 complex organic substances, there does not occur in any 

 reaction, as far as known, either a transformation or a 

 production of enzyme such as occurs in vivo, hence, 

 when a single enzyme is present it carries out but one 

 step of the reactions, but when, as in the case of diastases 

 as ordinarily prepared, the enzyme is not a single sub- 

 stance or unit body but a composite of a number of 

 enzymes or modifications of a given basic enzyme, serial 

 steps may occur as in vivo. Thus, if only a single 

 enzyme be present formaldehyde may be converted into 

 a monosaccharose, or a niouosaccharose into a disac- 

 charose, or a disaccharose into a polysaccharose such as 

 dextrin, or a dextrin into a higher form of polysaccharose 

 such as soluble starch, according to the enzyme or modi- 

 fied enzyme and initial substance present ; or the reverse 

 of any one of these processes may occur if proper con- 

 ditions are present, but never do any two successive 

 progressive or regressive steps occur unless through the 

 agency of two different enzymes ox modified forms of 

 one enzyme which are present. 



It will thus be apparent that the first step of syn- 

 thesis is determined by the character of the initial 

 physico-chemical mechanism and that all subsequent 

 reactions under given conditions are definitely prede- 

 termined ; in other words, the entire train of reactions 

 depends inherently upon the nature of the initial physico- 

 chemical mechanism of which the enzyme that starts the 

 serial changes is an integral part. 



Having a specific stereochemic system, such a sys- 

 tem in accordance with the laws of physical-chemistry 

 can exist in either a latent or active state, and that when 

 in an active state the reaction or reactions are always in 

 the direction of the establishment of equilibrium of 

 solution, every reaction or series of reactions being as 

 definitely predetermined as is every reaction familiar to 

 the inorganic chemist. The germplasm in the form in 

 which it is secreted may be regarded as being in the 

 nature of an exceedingly complex stereochemic system 

 which is from its iucipiency, or very soon is in a state 

 of physico-chemical unequilibrium, and in which, as a 

 consequence, reactions are set up which are manifested 

 especially in histological developments that ultimately 

 characterize the fully developed ovule, at which time a 

 state of physico-chemical equilibrium is established, as 

 is evident by the arrested developmental activities. This 

 state of physico-chemical equilibrium of the matured 

 ovule may be instantly changed to one leading to serial 

 definitely predetermined reactions by means of an acti- 

 vating substance or condition, such as certain ions or 

 inorganic salts, a spermatozoon, or a needle prick, by 

 initiating the first step of the reactions, the nature of 

 the succeeding reactions being predetermined primarily 

 by the inherent nature of the physico-chemical system 



