412 
The Health Exhibition. !j u ty> 
races must first be formed, as happens by isolation and in- 
breeding. By crossing the stock attributes of the form are 
increased, since new properties appear in the hybrids and in 
their offspring which are added to the sum of the attributes 
of both parents. A richly varied material is thus obtained 
by crossing kindred species or races. # 
On the basis of the following four faCts given by Darwin 
(i) the greater vitality of mongrels ; (2) their variability ; 
(3) the selection of the most suitable types of variable 
forms ; and (4) the survival of the most suitable and highly 
vitalised forms — it may be maintained that in the rule the 
specific types of the future will appear among the descendants 
of mixed races. But as there is no absolute boundaiy e- 
tween varieties and species, there can be only a giaduate 
difference between the origin of species from, the hybrids 
between species, and that from the hybrids between 
varieties. 
The views thus developed concerning the origin, of species 
differ only in appearance from those of Darwin. 1 hen- 
import lies merely here,— that they extend the vision of the 
inquirer who seeks to understand the causes and the natuie 
of Evolution. 
VI. THE HEALTH EXHIBITION. 
No. II. 
t N revisiting this display we certainly found not a few 
objects of interest which we had either overlooked 
on previous occasions or which had been recently 
added. At the same time our first impression — to wit, that 
many of the articles on view had but a very remote and 
doubtful connection with health, and were consequently here 
as intruders — was strengthened. 
The models representing portions of old London are now 
complete, or nearly so. But whether, when compared with 
modern structures, they give us quite as much scope for 
self-congratulation as is rashly assumed, is, to say the least, 
not proven. The London which they represent was certainly 
