ORGANIC REGULATION 109 
though the assumption is false it must be borne in mind 
that working hypotheses applicable to the available 
sense data are indispensable to the advance of knowl- 
edge and practice. With limited data crude and simple 
working hypotheses, sufficient to cover the data with- 
out further complication, are alone of practical use; 
and both knowledge and practice, in dealing with iso- 
lated and imperfect data, naturally proceed on crude 
hypotheses. Where we can as yet see no organic 
determination in isolated observations relating to life 
the best available description of them is in mechanis- 
tic terms such as we apply to the inorganic world. 
Such descriptions supply an indispensable basis for 
more adequate description and interpretation; but to 
give a general application to the crude working hypothe- 
ses on which these descriptions are based implies a 
disregard of the wider biological observations which 
indicate that further investigation would reveal organic 
determination. This disregard is a very marked fea- 
ture in current text-books of physiology. Each part 
of physiology, and even each subdivision of a part, 
is apt to be treated in isolation from the rest, with the 
necessary consequence that not only is no place left 
for the facts relating to organic determination, but 
the isolated details are very imperfectly described, as 
has been illustrated again and again in the course of 
these lectures. 
The real reason of this defect is that physiologists 
have been endeavouring to fit their descriptions to the 
imperfect current working hypotheses of physics and 
