124 A SCIENTIFIC APPRECIATION [ch. vi. 
Cuvierian level we mean the analysis of the body 
into its chief parts and organs, the corresponding 
study of the uses of the chief parts, the functions 
of the organs, and the correlation of the two. 
MacGillivray’s work seems to us to represent 
very precisely the transition from the Linnsean 
description of externals to the deeper Cuvierian 
description of the internal economy of the organism. 
Since his day, as is well known, the analysis of 
structure and of function has been pushed more and 
more deeply—from organs to tissues, from tissues 
to cells, and from cells to the living matter itself. 
From the old-fashioned study of habits there 
has been until within recent years some measure of 
recoil, partly because of the fascinations of other 
lines of inquiry, but partly because it did not in 
its methods keep pace with the deepening analysis 
of structure and function. And here we see one 
of the interesting features of MacGillivray’s work, 
that he felt the necessity of deepening the study of 
habits by bringing it into correlation with the results 
of anatomy and physiology. 
Generalising the twofold lesson which is so 
forcibly suggested by MacGillivray’s British Birds , 
we may say, in the first place, that natural history 
(in the narrower sense of oecology or bionomics) 
cannot be either stable or progressive, if it stand 
aloof from the results of the anatomical and 
physiological disciplines ; and, in the second place, 
that these disciplines are saved from losing per¬ 
spective and interest by being kept in touch with 
