2 66 | THE ORCHID REVIEW. 
CATTLEYA—WHAT CONSTITUES A SPECIES? 
A QUESTION which has been more or less definitely alluded to on more than 
one occasion in our pages, is again raised by a correspondent with respect 
to the genus Cattleya, namely, ‘‘ What constitutes a species?’ There are 
certain Cattleyas which are treated in the most diverse fashion by different 
writers. Thus, to give examples, we find Cattleya aurea, C. Dowiana 
aurea, or C. labiata Dowiana aurea; C. Mossiz or C. labiata Mossie ; 
C. amethystoglossa or C. guttata Prinzii; C. Leopoldi or C. guttata 
Leopoldi, &c., which is extremely perplexing to those who like to label 
their plants correctly. Surely it ought to be possible to arrive at something 
more nearly approaching uniformity. It is the old question again—‘‘ What 
is a species?” and as it is likely to crop up periodically, a few general 
remarks on the subject may be useful. 
Many of the differences alluded to, which we deplore as much as anyone, 
arise from differences of opinion among authors as to what is a species and 
what only a variety. Formerly it was commonly believed that species were 
separated by hard and fast lines, and could be measured and weighed, so to 
speak ; but now we recognise that there is no infallible criterion by which 
they can be distinguished from each other. All that one can say is that 
there are certain forms, more or less unequally related to one another, 
forming little groups, which, like satellites, are generally clustered around 
some other form. Hence the work of the botanist is to ascertain the rela- 
tion of these forms to each other, and to arrange them as species and 
varieties according to the amount of their respective differences. Incident- 
ally it may be remarked that the arrangement of species into genera, or 
genera into families, has to be dealt with in precisely the same way. 
The reason why organisms are related to each other in this particular 
way is now pretty generally understood, and a very few words in connection 
with the present subject will suffice to make succeeding remarks clear. 
Supposing a plant to become widely diffused, it almost invariably comes 
under the influence of changed conditions of existence, and as every part of 
an organism is closely related to its complex conditions of life, a correspond- 
ing change in the organism itself takes place. Hence variations arise in 
different geographical areas. In course of time, by a continuation of the 
process, new forms appear and the older ones become extinct, and thus, 
successively, varieties, sub-species, and very distinct species are evolved: 
Species themselves may give rise to groups of allied species in the same 
way. Varieties may therefore be termed species in course of formation, or 
incipient species, which readily explains why no hard and fast line can be 
drawn between the two. 
Returning now to the genus Cattleya, the unequal relation of the 
different forms to each other, and the way some of them are clustered 
