257 



under the influence of the gall-animal than under normal circumstances. Hence we 

 come to the conclusion that either the enzyme-substrates may serve as food for the 

 heredity units or enzymes to which they belong and may give rise to their multi- 

 plication, or that the gall-animal, beside the enzyme substrate, also supplies enzymo- 

 sites 1 ), that is to say a special enzyme food. The latter supposition will pro- 

 bably be the right one, for the real enzymes are in their origin in no way dependent 

 on their substrates, as we learn from almost every experiment with microbes 2 ). 



The enzymosites apparently correspond to Abderhalde n's Bausteine of the 

 specific living proteids, that is of the protoplasm. That, in case these enzymo- 

 sites differ, different heredity units or protoplasm micells will develop from the mix- 

 ture of units from which the latter is built up, is to be expected. For if we remember 

 in how remarkable a way in elective culture experiments with microbes, the thereby 

 obtained floras depend on nutrition, we may safely conclude that the same will be 

 the case in the subtle world of protoplasm molecules. 



That from the gall-animal no enzymes pass into the plant, is in accordance with 

 the fact that foreign exoenzymes commonly do not enter living cells. The diastase, 

 which in the distilleries occurs in great quantity in the food of yeast, which consists 

 for a great part of malt, does not penetrate into the yeast-cell. Experiments pur- 

 posely carried out with other exoenzymes and various kinds of other microbes have 

 invariably given the same result. The possibility of endoenzymes passing by diffusion 

 from one living cell into another is of course wholly excluded 3 ). 



On the other hand, in the range of immunology, facts are known which prove 

 that living cells sometimes take up enzymes from their surroundings. 



In those cases namely when acquired immunity is hereditary the thereby con- 

 cerned substances must needs belong to the heredity units, hence to the enzymes. 



They give evidence that D a r w i n's view, according to which the gemmules 

 of his pangenesis hypothesis freely move within the organism, is true in certain 

 cases, at least for the higher animals. Non-hereditary immunity might be caused by 

 freely moving enzymes, unable to enter the cells. 



Van C a 1 c a r's opinion that the anti-bodies of the serologists are ferments, that 

 is enzymes, is thus undoubtedly right. He says 4 ) : Whichever immunity reaction is 

 examined, it is constantly found that the whole course of these reactions depends on 

 the action of two substances, one of which having in all respects the character of a 



') Sitos, food. 



2 ) Many diastatic bacteria for example produce diastase without the presence of 

 aniylum in their food. This must be ascertained by a special experiment, amylum being 

 the only known reactive on diastase; the literature proves that this has sometimes 

 been forgotten by the investigators. 



3 ) It is not impossible that endoenzymes such as zymase are to some degree capable 

 of ordinary diffusion (which is quite another thing than penetrating into living protoplasm) . 

 Gelatin can slightly penetrate into agar, likewise starch and even the carbon of Indian 

 ink. Gold seems able to penetrate indo lead. In the protoplasm of luminous bacteria 

 no disposition for diffusion is to be observed. However the pathological light of Noctiluca 

 miliaris, described byde Quatrefages, seems to repose on the entering of the photoplasnf 

 or luciferase into the cell-sap in which the luciferine must then be dissolved. 



4 ) R. P. van Calcar, Voordrachten over algemeene biologic, pag. 182 and 188, 

 Leiden 1915. 



M. VV. Beijerinck, Verzamelde Geschriften ; Vijfde Deel. I? 



