HOMOTYPOSIS IN THE VEGETABLE KINGDOM. 
3G3 
(i.) When an individual of any species produces a number of undifferentiated like 
organs (homotypes) these are not exactly alike when measured with regard to any 
character. They exhibit a certain degree of variation combined with a certain degree 
of likeness (homotypic correlation). 
(ii.) The homotypic correlation as tested for twenty-two series of homotypes in a 
variety of species in the vegetable kingdom, has a mean value between ’4 and ‘5. Its 
exact determination is rendered difficult by a number of conflicting factors; but it 
seems very possible that the actual value of pure homotypic correlation, i.e., the 
correlation due to the individuality of the plant as apart from the influence of 
environment, &c., diffei's but little from the mean value stated above. 
(iii.) If a character occurs in a series of homotypes, it will be found to have in the 
individual a variability 80 to 90 per cent, of the variability of this character in the 
species at large. It is thus seen that variability is a primary factor of living forms, 
and is not in any way dependent on sexual reproduction. 
(iv.) With a certain hypotliesis as to cross homotypic correlation, i.e., the correlation 
of two different characters in homotypes, namely, that it is the product of the direct 
homotypic and of the organic correlations, it woidd follow that the mean fraternal 
correlation would equal the mean homotypic correlation. The mean of twenty-two 
homotypic series is found to be sensibly identical with the mean of nineteen fraternal 
series. A direct investigation of the value of the cross liomotypic correlation is only 
made for two cases, that of the mushroom gill and that of the ivy leaf The cross 
homotypic correlation is not found to differ very widely from the product of the 
direct homotypic and the organic correlations in these cases, but the results are not 
close enough to be conclusive, 
(v.) It would seem, if (iv.) be true, that heredity is only a phase of the principle 
of homotyposis (ii.), and that the numerical value of its constants may be found from 
that principle. 
(vi.) No relation whatever could be found between the intensity of variability and 
that of homotyposis in the twenty-two series dealt with. Nor was any relation to 
be observed between the relative simplicity of the organism and the intensity either 
of its variability or its homotypic correlation. Regarding heredity as a case of 
homotyposis, there seems no reason to suppose, as it has been suggested, that 
variability has decreased and heredity increased in the course of evolution. On the 
contrary there seems some ground for supposing that homotyposis (and therefore 
heredity) is a primary factor of living forms, a condition for the evolution of life by 
natural selection, and not a product of such selection. If the mushroom, the poppy, 
and the beech show approximately equal homotyposis, it seems well nigh impossible 
to consider it as a factor of life, increasing with advancing evolution. 
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