150 A SCIENTIFIC APPRECIATION [ch. vi. 
and it is but an inference to say varieties execute 
functions different from ordinary specimens.” 
One cannot help feeling that MacGillivray was 
on the line of finding a solution of his problem, but 
that he was kept back by his conviction that 
“ Nature has been desirous oifixing the bounds ” of 
species and varieties alike. He narrowly escaped 
making a great discovery. 
It is very interesting to find, separated by a 
page of the Journal, a careful inquiry, with 
measurements, into the varieties of fox in Scotland, 
and, on the other hand, his frank confession of the 
mystery of variation, which is, indeed, part of the 
central mystery of life itself:— 
“ It is of course easy to refer all occurrences 
and all productions to the great source of beauty 
and variety in Nature; but it is the business of the 
naturalist to search for immediate causes, even 
though the search be likely to prove fruitless, and 
though we should be in danger of setting that down 
as a cause which is perfectly inadequate to the 
office, whilst the true cause remains hidden, and 
unadapted to human comprehension. If, however, 
no cause can be discerned or surmised, it is equally 
the business of the philosopher to ascribe the 
circumstance to the superintending agency of God; 
at least until further discoveries have been made, 
very many circumstances in connection with our 
subject must be disposed of in this way. 
A Teacher. 
We cannot close this appreciation without 
referring to MacGillivray^ influence as a teachei. 
Some of his students who rose to. positions of 
