MAaRcH, 1914:] THE ORCHID REVIEW. 71 
segregate, while crosses between so-called species were said to give a stable 
offspring. Evidence is rapidly accumulating that this is not true as far as 
the latter are concerned, that species-hybrids also segregate. 
The lecturer then remarked: “I therefore claim that the origin of 
genotypes by crossing is of much wider application than was formerly 
supposed, that perhaps it is of universal application. I further claim that 
the genotypes are the real, long-sought for units of the natural system, and 
I propose that in future the term species be limited to them, in accordance: 
with the view held by systematists for ages that ‘species’ is the paaper: 
term for the units of the natural system.” 
He next discussed the question of Progressive Mutation, as illustrated. 
by the work of Prof. H. deVries. upon CEnothera Lamarckiana,. and 
remarked that it had now been shown that this plant was not a pure 
genotype, and consequently could not serve as a reliable basis for the study 
of the origin of mutants. Nor did the speaker know of a case in which 
progressive mutation from a pure genotype had been proved. 
Mutation by loss of Factors was also considered, only to be dismissed 
as hypothetical, and it was submittéd’that but one thing was proved, viz.: 
that the real units of the living kingdom are genotypes; that such genotypes. 
can, under proper precautions, be kept pure for an indefinite time; and 
that there is no certain evidence that they can be changed in any other 
way than by crossing. 
In discussing the reason of the apparent variability of a species in the 
Linnean sense, the author remarked that a Linnean species is a collection of 
independent stable Jordanian species, and if one were to consider, as 
Darwin did, the former as a unit, the small species contained in it must 
naturally appear to be deviations of the type—in other words, varieties. 
If, then, one further sees that between Linnean species which one considers 
to be units, transitional forms exist, it is perfectly logical to build up a 
theory that one species can change to another by means of its variability. 
But he deprecated drawing inferences as to the indefiniteness of specific 
limits from a bare knowledge that intermediates exist, and he expressed his. 
firm conviction that no transmittable variation exists, but that all apparent 
variability is due to an original cross. 
Finally the author touched upon the origin of species before sexual 
reproduction took place, but remarked that this is mere speculation. 
In conclusion he offered the following deductions :— 
(1) Ifa species is a perfectly stable genotype, reproducing faithfully its. 
kind for ever, unless crossing interferes, all differences between the 
individuals belonging to 2 genotype must be non-inheritable modifications. 
(2) Inheritable variability does not exist, with the always possible 
exception of mutation through loss of factors. All that has been described as. 
