THE LAAV OF SEPARATION OF CHARACTERS IN CROSSES. 243 
THE LAW OF SEPARATION OF CHARACTERS IN CROSSES. 
By Professor Hugo de Veies. 
[Translated by permission from the Report of the Deutsche Botanische 
Gesellschaft. 1900. Vol. XYIII.] 
(Preliminary Communication.*) 
According to the hypothesis of Pangenesis the character of a plant, as a 
whole, is composed of definite units. These so-called elements of the 
species, or elementary characters, are assumed to be associated with 
material bodies conveying them. Each single character has its special 
form of such material body.t 
Transitional stages between these elements are as rare as those between 
chemical molecules. 
For many years this principle has formed the starting-point of my 
researches. Many important consequences are deducible from this 
principle and can be experimentally proved. My trials have been made 
partly in the domain of variability t and mutability, and partly in that of 
crosses. 
In this last direction, however, the point of view from which investiga- 
tion starts must be entirely reversed. It is requisite that the idea of the 
species as opijosed to its composition of independent factors should be 
left in the background. § 
The present doctrine of crossing treats species, sub-species, and 
varieties as the units whose combinations can be effected and studied in 
the crosses obtained. A distinction is drawn between mixture of varieties 
and true hybrids between species. According to the number of the 
parental types we speak of diphylic and polyphylic crosses, of triple and 
quadruple hybrids, and so on. 
This mode of regarding the subject must, to my mind, be abandoned 
for physiological research. It suffices for systematic and horticultural 
purposes, but not for a deeper knowledge of the species. 
For it must be substituted the principle of the crossing of the specific 
characters. The units of the specific characters are to be regarded and 
studied as sharply separated quantities. They must be treated as inde- 
pendent the one from the others, in every case and so long as no reason 
presents itself to the contrary. In every experimental crossing, there- 
fore, only one character or a definite number of such is to be taken into 
consideration ; the rest can, for the time being, be ignored. Or rather is 
* The detailed description of my experiments, together with the theoretical 
explanation, I purpose shortly to publish in a larger work upon the emjDirical units of 
specific characters and their origin— "The Theory of Mutation" {Die Mutations- 
theorie). 
f Intracellulare Pangenesis, pp. 60-75. For the. contrary opinion, viz., that in 
each material-conveying body the entire character of the species is embodied, see ihid. 
pp. 47-60. 
% Vide these " Berichte," vol. xii., 1894, p. 197. 
§ Intracellulare Pangenesis, p. 25. . . 
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