Mode of Inheritance of Ada2')tive Characters. 67 



establish the fact that the number of ferments, or formative 

 substances in the nucleus, diminishes with the progress of 

 differentiation, we should have a comparatively simple and 

 intelligible explanation of the specification of nuclei and the 

 limitation of development." Applying this hypothesis to 

 the foregoing remarks in this paper, heredity would depend 

 on the property of the nucleus to give rise to enzymes in 

 certain directions or of a certain character, under appropriate 

 stimulus. The effect of the cells upon one another, in de- 

 velopment, would be to impose upon the nucleus of the cell 

 a tendency to set free enzymes that adjusted the cell to 

 meet the necessities of the community. Natural selection, 

 by elimination of individuals, and the internal adjustment 

 by the struggle for existence amongst the organisms of the 

 community, would bring about the necessary co-operation 

 in development, or symbiotic characters. There would be 

 a constant elimination of those cells which did not work 

 for the good of the community. The tendency of these 

 enzymes, in the specialisation of plant tissues, would be 

 to the formation of tissues of greater stability, while the 

 reverse would be the case in the specialisation in the tissues 

 of animals. Eegeneration would be due to the effect of 

 stimulus on the nuclei of cells not too far advanced in 

 specialisation, which, by means of the regulation of the cells 

 upon one another, would bring about the restoration of the 

 missing part. 



It is known to be through enzymes, in many cases, that 

 the food is brought into the condition capable of assimilation 

 by the tissue cells ; and it is likely enough that it is through 

 enzymes, or some related chemical bodies, that this material 

 is built up into the very living matter of the cell itself. 

 Animals and plants of enormous dimensions arise, by the 

 process of nutrition, from microscopic beginnings ; and what 

 is the stimulus that transforms all this food into living 

 material? The strictly specific modes of operation of the 

 enzymes that have been studied in animals and plants must 

 be remembered, and not only the great variety of purposes 

 to which they are applied, but the extraordinary relation 

 occurring between the amount of the enzyme and the 



