830 THE POPULAR SCIENCE MONTHLY. 



trained. Again, a dog is the most intelligent animal there is, and he 

 has a large brain in comparison to the size of his body. On the other 

 hand, however, if we examine some of the Monotremata, we find, as 

 already stated, that the brain is very large in proportion to the size of 

 the body ; but the animals of this group would by no means be taken 

 as a standard of animal intelligence. It appears very probable, there- 

 fore, that in young animals and in the lower classes of the vertebrates 

 the size of the brain has comparatively little to do with the intelligence 

 the animal possesses, but that in the higher vertebrates there is some 

 relation between the amount of intelligence and the quantity of brain- 

 matter. The question may be asked. Why is it that the elephant, since 

 it has the largest brain of any land animal, is not the most intelligent 

 animal there is — more intelligent even than man, if the intelligence 

 of an animal depends on the amount of its brain-matter ? The answer 

 to this question is easy. This animal being so large requires propor- 

 tionally larger nerves and larger nerve-centers, to supply the muscles 

 and sensory organs of his body, in the same manner that a larger mag- 

 neto-electric machine is required when twenty electric lights have to 

 be supplied by it than when it has to supply only ten. The elephant 

 has, in reality, a smaller quantity of brain material available for his 

 intelligence than the dog, because the dog has a much smaller body, 

 and requii-es smaller nerves. Moreover, the intelligence, it has been 

 proved, is situated in the uj^per part of the brain, or cerebrum, as it is 

 called. Now, the dog's cerebrum is very much larger, in proportion to 

 the size of his body, than that of the elephant, after allowing for the 

 general law that larger animals have smaller brains in proportion to 

 their body than smaller ones have. The number of smooth and tortu- 

 ous eminences called convolutions, separated by grooves, which cover 

 the whole surface of the upper brain or cerebrum has also been proved 

 to have something to do with the amount of intellect of the animal. 

 The brains of those animals which possess superior intellect are gener- 

 ally more highly convoluted and more deeply divided by the grooves 

 than those of lower intellect. This may be very well seen by compar- 

 ing the brains of the horse and the ox. It will at once be seen on look- 

 ing at the brains of those two animals that the horse's brain is the 

 more convoluted and altogether the more complex structure of the two. 

 The same thing may be seen in the brain of the pig on comparing it 

 with that of the sheep. As an example of brains where the convolu- 

 tions are few in number and the grooves between them very shallow, 

 we may take those of the echidna and ornithorhynchus, already men- 

 tioned as being very large in proportion to their bodies, while they 

 themselves are of a low type. The intellect of those animals evident- 

 ly does not correspond to the size of their brain. The probability is, 

 therefore, that their brain-matter is of a low type and consequently a 

 larger quantity of it is required. Besides these examples cited there 

 are many more that could be brought forward. It may be stated gen- 



