ORGANIC MOVEMENTS 47 



after disturbances ; they, moreover, may change the style of 

 building them, to suit the requirements of space, and they 

 also may build their house in an abnormal direction with 

 respect to gravity, should circumstances require it : instead 

 of building from above to below, they may also build from 

 below to above, and also sideways. The silkworm is said not 

 to form its web of silk if it is cultivated in a box contain- 

 ing tulle, and some species of bees which normally construct 

 tunnels do not do so if they find one ready made in the 

 ground, they then only perform their second instinctive act : 

 separating the tunnel into single cells. 



In all of these cases, except the one relating to gravity, 

 the state of affairs seems to be the following. What has 

 been changed from without is either the perfect result of 

 the full sequence of instinctive acts, or it is what might be 

 called an embryological state somewhere in this sequence, 

 that is, some state in the sequence that leads to the perfect 

 result. And the artificial change of the second class may 

 again be of two kinds : either something may be taken 

 away from what the animal had accomplished already, or 

 something may be added to the result of its activity, some- 

 thing, of course, that would occur in the process of normal 

 construction. In all these cases the animal will adjust its 

 instinctive movements to the actual state of matters, no 

 matter whether it has to do more or less than normally 

 more, if parts of its own construction are taken away, less, if 

 parts are added to it artificially. 



There can be no doubt that the term " regulation " is 

 justified in these cases. What then does this mean, and 

 what can it teach us as to our question about the autononric 

 character of instincts ? 



