EXPERIMENTS IN HYBRIDISATION, &c. 111 
three hybrids raised from the same parents, in the first, the pollen-parent 
may predominate in form in a certain part; in the second, the seed- 
parent may prevail in that part; while in the third, that part may be 
fairly intermediate between both parents ; while in regard to colour, these 
conditions may be exactly reversed. But this only includes one part of 
the hybrid, and the same law applies equally to every one of the parts; 
so that when the changes are rung on twenty or more different parts by 
the two parents, in both form and colour, we can well understand the 
many possibilities of variation in hybrids of the same parentage; and I 
venture to suggest that this law of Partial Prepotency, founded on actual 
facts observed in hybrids of Paphiopedilum, may perhaps throw some 
light on the question of variation in offspring of the same parents. Yet, 
notwithstanding this variation in the parts, it is a remarkable fact that in 
primary hybrids the whole plant taken together is fairly intermediate 
between the two parents, the balance of power being well maintained in 
the whole. 
The greatest extreme observed by me, out of many cases in 
Paphiopedilum, has been 58°6 per cent. of one parent, against 42-4 per 
cent. of the other, the great majority being approximately 50 per cent. 
of each parent. This hardly coincides with the popular belief that some 
hybrids resemble one parent, while others resemble the other; but this 
may be due simply to superficial observation, for where conspicuous parts 
lean towards one parent, the casual observer might easily be deceived, 
not noticing the inconspicuous parts which compensate for this by leaning 
towards the other parent. 
THE VARIATION OF SECONDARY HyBribs. 
Hybrids of the second generation, whether of two, three, or four 
species, differ notably from hybrids of the first generation of two species 
by reason of their much wider range of variation. Whether this be due 
simply to the increased factors in their pedigree, or whether apart from 
that, I have not yet been able to gather sufficient evidence to determine ; 
still, the fact remains that, from whatever cause, hybrids of the second 
generation are far more variable than those of the first generation. As | 
an illustration of this I will take two sets of hybrids in Paphiopedilum, 
in one of which we will consider the colour of the flowers, and in the 
other the habit, form, and colour of the leaves. Both groups are hybrids 
of the second generation, from three distinct species (7.e. a hybrid of two 
species crossed with a third species), and in both the law of Partial Pre- 
potency is remarkably evident. The first of the two sets was raised by 
M. Jules Hye-Leysen, of Ghent, between varieties of P. Spicerianum 
(Pfitz) and P. x nitens, the latter parent being itself a hybrid between 
P. insigne (Pfitz) and P. villosum (Pfitz). Some twenty-two hybrids 
have already flowered, many of them having been raised out of the same 
seed-capsule. Each of these hybrids has received a distinct name, and 
perhaps worthily so, from their wide variation and distinctness ; but for 
the sake of convenience I will allude to them as varieties of the original 
one, viz. P. x aureum. The following diagram will show their pedigree 
at a glance :— 
