TELEOLOGY AND MORPHOLOGY 139 
A house is certainly, to a great extent, an illustration 
of adaptation to purpose, and its structure is, to that 
extent, explicable by teleological reasonings. The roof 
and the walls are intended to keep out the weather; the 
foundation is meant to afford support and to exclude 
damp; one room is contrived for the purpose of a 
kitchen; another for that of a coal-cellar; a third for 
that of a dining-room; others are constructed to serve as 
sleeping rooms, and so on; doors, chimneys, windows, 
drains, are all more or less elaborate contrivances directed 
towards one end, the comfort and health of the dwellers 
in the house. What is sometimes called sanitary architec- 
ture, now-a-days, is based upon considerations of house 
teleology. But though all houses are, to begin with and 
essentially, means adapted to the ends of shelter and 
comfort, they may be, and too often are, dealt with from 
a point of view, in which adaptation to purpose is largely 
disregarded, and the chief attention of the architect is 
given to the form of the house. A house may be built in 
the Gothic, the Italian, or the Queen Anne style; anda 
house in any one of these styles of architecture may be 
just as convenient or inconvenient, just as well or as ill 
adapted to the wants of the resident therein, as any of 
the others. Yet the three are exceedingly different. 
To apply all this to the crayfish. It is, in a sense 
a house with a great variety of rooms and offices, in 
which the work of the indwelling life in feeding, breath- 
ing, moving, and reproducing itself, is done. But the 
