244 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
it immaterial whether the parents differ from one another in other 
respects ? For experimental purposes it is clear that the crosses the two 
parents of which differ only in one character form the simplest cases 
(Monohybrids, as opposed to Di-Poly hybrids). 
If the parents of a cross only vary from each other in one point, or if 
only one or a few of the points of difference be considered, they are in 
these characteristics antagonistic, but all others may be regarded either 
as neutral or immaterial for resulting calculations. The experimental 
crossing thereby becomes confined to the antagonistic characters. 
My experiments have led me to formulate the two following 
principles:* — 
1. Of the two antagonistic characters the cross always displays only 
one, and that one is fully developed. It is therefore in this respect 
indistinguishable from one of the two parents. Intermediate forms do 
not occur in such cases. 
2. At the formation of the pollen and the egg-cells the two antagonistic 
characters separate themselves. In so doing they follow in the majority 
of cases the simple laws of probability. 
These two principles in their more essential points were long since 
formulated by Mendel in the special case of Peas.t They have, how- 
ever, lapsed into oblivion and become misinterpreted. J They are, 
according to my experiments, fully established as regards pure crosses. 
The absence of intermediate forms between any two simple antago- 
nistic characters in the cross is perhaps the best proof that such 
characters are really definite units. § 
Innumerable examples, partly in my own experience and partly 
derived from literature, can be cited in proof of the correctness of these 
principles. That Poly hybrids so often present intermediate forms 
is obviously due to the fact that they have inherited some of their 
characters from the father and some from their mother. With Mono- 
hybrids, however, this is not possible. 
Of the two antagonistic qualities, Mendel names those visible in the 
cross the " dominants," and those latent the " recessive." 
Usually the systematically higher character is the dominant, or 
where the pedigree is known, the older ; for instance : — 
Dominant Recessive 
Papaver somniferum (high form) P. s. nanum 
Antirrhinum majus (red) A. m. album 
Polemonium cmruleum (blue) P. c. album 
and as of well-known origin, e.g. — 
Dominant Recessive Known since 
Chelidonium majus C. laciniatum 1590 
(Enothera Lamarckiana 0. brevistylis 1886 
Lychnis vesjpertina (hairy) L. v. glabra 1886 
* The "faux hybrides" of Millardet are entirely disregarded in this paper, but are 
treated of in the following one. 
f Gregor Mendel, " Versuche iiber Pflanzenhybriden," in Transactions of the 
Naturforscher-Verein in Briinn, vol. iv., 1865, p. 1. This important paper has been 
so seldom cited that I only first heard of it after I had completed the bulk of my 
experiments, and deduced therefrom the principles set forth in the text. 
X Compare W. 0. Focke, Die Pflanzemnischlinge, p. 110. 
§ Intracellulare Pangenesis, pp. 25, 26. 
