436 THE POPULAR SCIENCE MONTHLY. 



productive. It fits his central nerve-system for the most complicated 

 functions ; it sharpens his senses, and by it his mind, reacting upon 

 itself, is enabled to augment its own elasticity and versatility. Return- 

 ing to our starting-point, we ask, Is not this one of the means, perhaps ' 

 the principal one, by which the collectivity of living existence becomes 

 a self -improving machine ? As to the crystal, the parts of like struct- 

 ure and properties composing it ; as to the whole organism, the ele- 

 mentary organisms whose life makes up its life, so are related to the 

 whole of organic nature the single living existences, that is, the prop- 

 erties and functions of the whole are the sum of the functions and 

 properties of the individuals ; and if the individual living being is im- 

 proved by exercise, does not this also sufficiently explain the progress 

 of the aggregate ? Lucid as the supposition appears, on a nearer trial 

 it encounters serious difficulties. 



First, only the most highly organized animals are amenable to ex- 

 ercise, or, what means the same thing, trainable. After the generally 

 distributed companions of man, the horse and the dog, the most teach- 

 able animal is the elephant. Chamisso found intercourse with the apes 

 on board the Rurik uncommonly instructive, " for," as Calderon says 

 of the ass, " they are almost men," and he made the profound remark 

 that they might be able to bring themselves up to the mark if they did 

 not lack the property which Newton held to be one with genius, stead- 

 fastness. Carnivores, with the exception of the cheetah (Fells ju6ata)> 

 ruminants, and rodents, exhibit only moderate teachability ; yet Herr 

 Fritsch considered the draft-oxen at the Cape of Good Hope wiser 

 than the horse, and in Brazil and Thibet sheep are trained to carry 

 loads. Among the birds, the higher ones are the parrots, starlings, 

 bullfinches, and canary-birds ; the falcon ranks with the cheetah in 

 teachableness. Chameleons, snakes, and carp are only moderately 

 teachable. The training of fleas is only apparent ; they always per- 

 form their tricks under a kind of compulsion. The immense host of 

 other creatures all around us show no more aptitude for training than 

 they do, for the reason that every animal within its own circle has no 

 need of instruction ; what we call instinct affords to animals, without 

 effort of the individual, more than any exercise can. What practice 

 could teach birds to build warmer nests, to find the way south more 

 certainly, -or bees to solve their geometrical, spiders their mechanical 

 problems ? Instinct and perfectibility complement each other as it 

 were in the ascending series of animals to a growing sum, so that, 

 the more instinct retreats before perfectibility, by so much does the 

 living being stand at a higher stage. Secondly, although the animals 

 we have named, and many others besides, are susceptible to exercise 

 and trainable, animals still do not of themselves exercise and perfect 

 themselves, but do so only when man takes them to school. Therefore, 

 the animals around him appear less susceptible to training, the lower 

 the stage at which he himself remains. Higher races of men would 



