The Enzyme Theory of Heredity. 



Proceedings of the Section of Sciences, Kon. Akademie van Wetenschappen, Amster- 

 dam, Vol. XIX, 1917, p. 1275 1289. - Verscheen onder den titel De enzym-theorie 

 van de erfelijkheid in Verslagen Kon. Akademie van Wetenschappen, Wis-en Natuurk. 

 Afd., Amsterdam, Deel XXV, 1917, biz. 1231 1245. 



Combining the results of the enzymological researches of recent years with those 

 obtained by the experiments on heredity, an insight is obtained into the nature 

 of the thereby concerned substances which deserves attention. 



The most acceptable theory of heredity is the conception that the living part of 

 the protoplasm of the cell is built up from a great number of factors or bearers, dif- 

 ferent from one another, which determine the hereditary characters of the organism; 

 at the cell division these bearers double or multiply, in consequence of which the 

 characters, latent or unfolded, are transferred to the daughter-cells. They are called: 

 difterirende Zellelemente (Mendel), gemmules (Darwin), biophores, pangens, 

 gens, character units, heredity units, Mendelian factors, or factors 1 ). 



How they appear in the cell, how they behave to nucleus, chromidia, chromo- 

 somes, and other cell-organs, and many questions more, form the subject of the here- 

 dity researches of to-day, which however start from the supposition that the said 

 theory is in the main right. Nor does the observation that heredity units or factors 

 may occur in latent condition and must then be activated by special kinds of food, by 

 alcalies or acids, or other stimuli, touch the fact of their existence. 



By the side of this view stands another, only apparently quite different, namely 

 that the living part of the protoplasm is built up of a large number of various en- 

 zymes. A nearer consideration of these two views shows that heredity units and 

 enzymes means the same -}. 



Hence the fundamental conception here to be proposed, that every hereditary 



') G. J. Mendel, Versuche iiber Pflanzen-Hybriden. Verhandl. d. naturforschenden 

 Vereines in Briinn, Bd. 4, Abh pag. 42, 8. Februar u. 8. Marz 1865. C. Darwin, 

 Provisional hypothesis of Pangenesis. Domestication, ist Ed. T. 2, pag. 357, 1868. 

 2nd Ed. T. 2. 349, 1875. --Hugo de Vries, Intracellulare Pangenesis, Jena 1889, and 

 the American edition, Intracellular Pangenesis, Chicago 1910. V. Haecker, Allgemeine 

 Vererbungslehre, pag. 265, 1911.-- M. W. Beijerinck, Mutation bei Mikroben. Folia 

 microbiologica. Bd. i, pag. 24, 1912. W. Johannsen, Elemente der exakten Erblich- 

 keitslehre. 2nd Ed. pag. 143, 1913, etc. 



-) Younger physiologists (as E. Abderhalden, Physiologische Chemie, 3. Aufl. 

 Theil 2 pag. 997, 1915) wrongly use anew the old and equivocal word ferment, instead 

 of the practical and clear word enzyme. The history of the introduction of the word 

 enzyme is as follows. In Verhandlungen des Naturhistor. und Medicin. Vereins zu Heidel- 

 berg*, Sitzung am 4. Februar 1876, Bd. i, N. F., the account of a lecture of Kiihue begins 



