HIBERNATION AND ALLIED STATES IN ANIMALS 111 



into a condition which is related to that of hibernation. 

 The so-called encysted stage of protozoa is perhaps 

 analogous and similarly preservative of the individual 

 and the species. 



The study of a subject like the present one gives rise 

 to many questions. Can the molecular machinery of 

 life entirely stop, and yet be set in motion again ? We 

 know that cold-blooded animals may be frozen and 

 completely restored to a natural condition. This and 

 the encysted condition of protozoa are suggestive of 

 such a possibility. 



Yet in insects a condition of perfect quiescence is 

 accompanied by the most wonderful changes. The 

 worm-like caterpillar becomes within its cocoon the 

 butterfly, with locomotive powers immeasurably greater. 



For myself, the more I study biological problems, the 

 less am I inclined to subscribe to rigid formulae of 

 being. The study of a single group of animals from a 

 physiological point of view, much less that of a single 

 individual, does not suffice to enable one to lay down 

 laws that will apply to similar processes in other groups 

 of animals except in the most tentative way. I can 

 never forget the lesson of my marmot that did not 

 hibernate at all, and what modification of present 

 views more extended study of this subject of sleep in 

 all its phases will produce, it is impossible to say. 



All my own studies have greatly impressed me with 

 the plasticity of living things, their power to adapt to 

 altered environments, and, if I might suggest one of 

 the great changes that is likely to come over the 

 biology of the future, it is a recognition of the above 

 fact; so that we will cease to generalise so widely 

 from such narrow data, or rather, perhaps, we will be 

 ready to believe that phenomena, very different from 

 those we know, may be possible in the realm of living 

 things. 



