172 THE entomologist's record. 



their modification ; and (2) cold considered as a mere stimulus, in 

 response to which the hybernating condition may be periodically 

 assumed — the power of hybernating having been already established 

 by a longer or shorter course of natural selection, but the organism 

 needing in some instances a signal, as it were, to set the machinery 

 going at the appropriate time. The distinction is implied, though 

 perhaj)s not expressed, in the statements quoted from Weismann ; 

 and if it be kept in view, all apparent inconsistency in the latter 

 writer's argument will disappear. 



Mr. Kane, no less than Mr. Tutt, acknowledges the adequacy of 

 natural selection for the production of the hibernating habit in its 

 various degrees of manifestation ; but by calling in the aid of 

 " inherited habits, morphological adaptations and acquired instincts 

 (which may be termed ancestral memories)," to supplement the simple 

 operation of natural selection, he is treading on highly debatable 

 ground, and will certainly fail to carry many biologists with him. 

 There would be hardly the amount of agreement that he appears to 

 anticipate in the position that " acquired habits .... play an 

 important part in animal evolution," though that doctrine would 

 assuredly meet with the approval of Mr. Herbert Spencer. Mr. 

 Kane is no doubt right in holding that some forms have not yet fully 

 adjusted themselves to their present conditions, and his excellent 

 suggestion that full observations should be made and recorded of the 

 behaviour of various species imder natural conditions, in different 

 climates, ought to be widely taken up. Some detailed knowledge is 

 already available on this point, but far more is wanted. 



There still remains the question of the physiological history and 

 meaning of the winter sleep. Mr. Kane points out that cold directly 

 induces torpidity among both the higher and lower animals. But he 

 would seem to overlook the fact that, as was clearly shown by 

 Marshall Hall, the torpor directly induced by cold in the higher 

 animals is physiologically quite distinct from hibernation. The 

 ultimate origin of the habit is no doubt to be sought, as Mr. Tutt 

 suggests, in the capacity for rest possessed by all protoplasm. Physi- 

 ologists know that every tissue in the body has its alternating periods 

 of rest and activity, succeeding one another rapidly or slowly, 

 rhythmically or irregularly, with apparent spontaneity or in answer 

 to a definite external stimulus, according to the various parts to be 

 played by the particular tissue in relation to the life of the entire 

 organism. The same phenomenon in the case of the protozoon is 

 recognisable by every observer. Take, for instance, the alternation of 

 rest and activity exhibited by a vorticella — now in response to an 

 external stimulus, now apparently resulting from causes arising within 

 the unicellular organism itself. This capability of protoplasm gives 

 the requisite material for natural selection to work upon, and we find 

 accordingly few groups in the animal world in which some means of 

 the nature of hibernation or protracted quiescence is not adopted as a 

 defence against certain vicissitudes in the environment. As far as 

 the lower forms of life are concerned, the matter is a simple one ; 

 and the physiologist knows that Avhat applies to an unicellular organism 

 like the vorticella, applies in the main to each component cell of the 

 various tissues that make up the bodies of the metazoa. But with 

 every successive step in the upward scale, fresh coordinations and 



