ANATOMICAL NOTES ON MALAY APES, 87 



That is, the gibbon carries a diet about one-twenty-fifth part 

 of his weight and spends one-hundredth of his internal economy 

 in carrying it and doing the first part of his digestion. On the 

 other hand, this white-eyed, steel-grey monkey has to perform 

 his locomotion with a diet load nearly one-third of his weight 

 and expends as much as one-twenty-fifth part of his bodily 

 substance on his stomach, as much as he does on his liver. 



And it is from the stomach that the brain receives its im- 

 pulse for work. And the progress is from a plentiful food sup- 

 ply that is difficult of digestion, such as the steel-grey monkey's 

 staple and abundant diet amongst the bamboo leaves, to a 

 scarcer and more inaccessible but more easily digestible food, 

 as the green acid figs, and other fruit foods of the gibbon. 

 On the one hand an intricate, large and expensive apparatus 

 is used ; on the other a simpler and smaller organ does the 

 work. The extensive foraging excursions of the gibbon en- 

 tail much more brain labour than the ' barn-door ' feeding of 

 the grey monkeys. The gibbon has added to his brain and sub- 

 tracted from his stomach. And it was this simple mathema- 

 tical calculation that brought us to where we are. 



Such a statement the facts of the case bear out. We tabu- 

 late the brain statistics of the above group of monkeys, and 

 this is how the matter stands :-— 



Actual Brain | Relative Brain 

 Weight. Weight, 



Hylobates lar, ... j 12.5 lbs. 



S. albocinereus, ... | 15.5 lbs. 



1,607 g rs - .0187 



1,113 g rs - .0120 



The relative weight of the brain is in inverse ratio to that of 

 the stomach, the gibbons spending T \ of their tissue on brain 

 + Ts-o on stomach, while the grey monkey spends about -^ on 

 his brain -f- -£ T on his stomach. Man has reached the furthest 

 point in this direction ; he spends about T \-^ of his economy 

 upon a stomach, he gives about -fa to his brain. In a young 

 rang-utan (7 months), 1 found the brain weighing one-four- 



