CEREBRAL HEMISPHERES AND MEMORY 255 



power-rate of activity of the muscles is proportional 

 to their mass, and something similar may be true of 

 the glands. The results obtained by weighing the 

 brain of man have proved, conclusively, that the mass 

 of the cerebrum, unless it falls below a certain mini- 

 mum, in no way affects the degree of intelligence. 

 The same facts prove that the number of ganglion- 

 cells bears no direct relation to the degree of intelli- 

 gence. The small dog has fewer ganglion-cells than 

 the large dog, inasmuch as the size of the cells varies 

 comparatively little in dogs of different size. 



Speck, who has called attention to this difference 

 between muscles and brain (8), has also made another 

 important discovery, namely, that in case of lack of 

 oxygen associative memory first disappears. He in- 

 haled air deficient in oxygen from a gasometer, and 

 counted during his experiments. As soon as the 

 partial pressure of the oxygen of the air fell below 

 8 % of one atmosphere, he forgot to count very soon 

 and then fainted, although the other functions of his 

 body showed no change. Speck concludes from this 

 that the cerebral hemispheres are most sensitive to a 

 lack of oxygen. It is not absolutely necessary to 

 conclude from this that the cerebral hemispheres 

 have relatively the greatest metabolism of all the 

 organs. It is possible that lack of oxygen affects the 

 physical qualities of colloids in the brain in such a 

 way as to make the functioning of the mechanisms of 

 associative memory impossible. I have shown that 

 lack of oxygen leads to a liquefaction of the cell-walls 



