28 THE ORCHID REVIEW. (FEBRUARY, I917- 
wrote about are real and tangible things, things that occur in nature and 
that can be met with every day, not about Dr. Lotzy’s phantom present- 
ments. If Dr. Lotzy has found a “ perfectly stable genotype, reproducing: 
faithfully its own kind for ever, unless crossing intervene ’—as he formerly 
defined it—it is a Mendelian homozygote, and he had better call it one. 
** Species” are not to be removed from the purview of the systematist by 
such verbal jugglery. Species we have long known as freely intercrossing 
communities, and cross-fertilisation gives a stimulus to variation, while 
self-fertilisation tends to uniformity. Crossing is, therefore, a potent cause 
of variation, but it is not the sole cause. There are multitudes of 
geographical forms that must have arisen without crossing (to use the 
term in the sense intended). 
Take the labiate Cattleyas, forexample. The species, with few exceptions, 
occupy separate geographical areas, but where C. Warscewiczii and C. 
Dowiana (aurea) grow together the natural hybrid C. Hardyana occurs—its 
hybrid origin has been confirmed experimentally in several collections. 
The labiate Cattleyas cross freely in gardens, but the numerous hybrids are 
not found in a wild state, because the species grow apart, and hybridisation 
is largely a question of opportunity. The parent forms have clearly arisen. 
by divergent evolution, or adaptation to changed conditions, for the whole 
fundamental structure of the body is due to the gradual accumulation of 
characters that arise as the result of the reaction of the organism to the 
environment, owing to its power of directing the chemical and physical 
forces to which its existence is due. Under such changes it would retain 
such previously acquired characters as were essential, including cross- 
fertilisation—and necessarily the agencies by which it is effected. Such 
changes would usually be accompanied by migration and geographical 
re-arrangement, bringing allied species together and thus affording the 
opportunity for hybridisation to occur, as we see in such numerous 
instances to-day. Hybridisation may be regarded as an extension of cross- 
fertilisation beyond specific limits, and Kerner long ago recognised it as on? 
of the underlying causes of the origin of species, though not the sole cause- 
Lotzy rejects Darwin’s contention that changed conditions give an im- 
petus to variability, and with it the doctrine of the inheritance of acquired: 
characters, apparently because, as he defines it, “very few of the adherents of 
the theory believe in the orthodox way that external conditions first change 
the soma, and through this subsequently the constitution of the gametes.” 
This, however, is a mere begging of the question. It is the old sophism. 
that C a character ceases to be acquired as soon as it becomes heritable; ”” 
and like unto it is the phase that “ inheritable variability does not exist.” 
