HIBKKNATION, ETC., IN ANIMAIvS. 65 



inau lias not aud which iii a souse makes them wiser thau our scieme aud wiser than 

 they kuow, for they act reflexly as it were. Ofteu my iparmot would be heard iu the 

 night scraping the straw about him prior to a storm that did uot reach us for mauy hours 

 after. 



Marshall Hall laid it down as one of his principal conclusions that in hibernating 

 animals " muscular irritability" is increased. 



If the term reflex be substituted for muscular I believe the conclusion is correct. I 

 found as a result of scores of trials that when the marmot was hibernating he was more 

 sensitive to slight stimuli such as blowing on the hairs of the skin than when merely 

 sleeping. Plainly this was not a case of muscular irritability at all but it does indicate 

 that the reflex mechanism is more excitable as it is for example in an animal under the 

 influence of strychnine, and as it is in animals from which a portion of the cerebrum has 

 been removed. 



It may be because the unconsciousness is so profound, i. e., the brain so far from its 

 ordinary functional activity, for it is well established that the brain inhabits the .spinal 

 cord normally to a certain extent. 



Apparently this increased reflex excitability must be to the advantage of a hibernat- 

 ing animal, for the cord and medulla oblongata are the parts of the nervous centres that 

 especially preside over the functions of organic life which are necessary to maintain 

 a mere animal existence. 



All problems of a biological kind must ultimately be referred to cells and so 

 with this of hibernation. Indeed it would seem that unicellular animals pass 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 mauy Cjuestions. 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 wonder- 

 ful 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 formulfe 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 cautious 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 generalize 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. 



Sec. TV., 1892. 9. 



