50 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



tionally, but his caterpillars also formed typical tissues by 

 using leaves of abnormal forms intentionally prepared, or by 

 using leaves of plants that are not normally employed. 



It is to be hoped that future research will follow in 

 the track of the one last mentioned, that is to say, that 

 entomologists will observe the behaviour of their insects 

 with the full appreciation of the bearing of the study upon 

 the problems of theoretical biology, and not only in the 

 interests of natural science proper. 1 



f. CONCLUSION 



Here, then, we may close our discussion of instinctive 

 movements. It has yielded some indications of vital 

 autonomy in the field of instinctive life, but no real, 

 absolute proofs ; for the facts are too scanty at present to 

 allow any definite answer to the chief problems appearing 

 in this field, viz. the problem of the nature of the stimuli 

 and of the regulability of instincts, the latter problem being 

 reducible to the former. It is probable that both these 

 problems will be answered some day in favour of vitalism, 

 that, as matters stand, no machine can in fact be imagined 

 capable of accounting for what happens. 



Such a result would not be in conflict with the analytical 



1 Once more I call attention to the "turning over" of animals when put 

 into an abnormal position, though we are not accustomed to speak of instincts 

 proper in these cases (see page 31 f.). No doubt the process of turning in 

 its single phases is exclusively made up of "regulations." Are they of such 

 a type that the "whole " of the actual abnormal state enters in some way, or 

 are they mere sums of single acts, purposeful only on account of their per- 

 former's general organisation ? Certain experiments of Preyer's seem to me to 

 deserve more attention with regard to our question than they have generally 

 received (Mitt. zool. Station Neapel, vii., 1886. See also Jennings, 

 Behaviour of the Lower Organisms), 



