Kleinere Mitteilungen. ocg 



circumstances. They fluctuate with those circumstances. Yet, energetic as 

 they are, they are not inherited: only the real factors, the stimiilaters, the actual 

 causers of the properties of the habitus these are all truey inherited, what 

 thus is not inherited is only the measure of activity of definite factors, since 

 this measure of activity is a function of circumstances: it is something 

 accidental and temporary. If thus a plant is brought under special circum- 

 stances so that it acquires a deviating habitus, therefore becoming "modi- 

 fied", then those factors which define such a modification are present in 

 the "normar plant also. The offspring of such a modification, that yields 

 again so-called normal plants, possesses those factors which determine the modi- 

 fication also: indeed they are not so typically exhibited because circum- 

 stances do not permit it. Only through minute statistical analysis can it 

 appear that those factors indeed are really present. Thus there exists 

 absolutely no difference between the modification properties and those of 

 heredity. They are both equally hereditary. The difference between genetic 

 and non-genetic factors does not exist. All factors are genetic factors. The 

 question is only that when under different circumstances, factors are not 

 all activied in the same way, nor all with the same measure of energy, 

 i. e. not all of them stimulate the plant to an equalh marked degree. Through 

 this hypothesis the bond of reconciliation is established in a very plain 

 way between the genetic and non-genetic factors. 



Through this hypothesis the doctrine of heredity has acquired a back 

 ground: the whole is in harmony with the foundations of modern physio- 

 logy, that viz: the living organism is a function of stimulations, and that 

 therefore a complete habitus is a function of stimulations. The rigid 

 notions of recent doctrines of heredity have not been in accord up to now 

 with the above stated fundamental principles of physiology. Let it be 

 clearly understood / do not say that external circumstances are the actual 

 constructors of the organism. No! The factors are and remain the formers 

 of the organism. The degree to which the factors are activated is however 

 a function of circumstances, even this influence remains constantly limited 

 within the prorince of factors. Yet because that from a single "property" 

 even a great number of factors may be present, all of which factors differ 

 more or less from each other, therefore, through different circumstances, 

 the habitus of a plant may vary even in accordance to the degree of 

 differences in which these factors are activated. The more factors there 

 are of such a "property" the more powerfully may the plant be modified. 

 Concerning the practical signification of this, I refer to my second treatise. 



Buitenzorg, August 1913. 



