Page:Popular Science Monthly Volume 16.djvu/865

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erally, then, that the intelligence of an animal depends principally upon the size of the brain in proportion to the size of its body, the size of the cerebrum, and also upon the number of convolutions and the complexity of its structure, although there are many exceptions to this rule which we are still unable to account for.

Another interesting point in connection with this subject is the great increase in the size of the brain that has taken place within the last few hundreds of years, without a corresponding increase in the size of the body in all animals. This very interesting fact we learn from fossil zoölogy. The brain of animals at the present day is much more developed than it was in former times. This may be owing to the struggle for existence which there is, the animals which are weaker in body and intellect gradually being extinguished by the stronger, so that only the latter remain and are allowed to propagate the species. We know that exercise and training strengthen the brain and increase its weight in man, so the probability is the same thing takes place among the lower animals. There is every likelihood, therefore, that the brain will still go on developing as time advances.—Land and Water.



DR. HERMANN GROTHE, of Berlin, has published a work on the textile fibers furnished by the world of plants, embodying the fruits of studies pursued among the yarn and cloth materials of all nations at the great Industrial Exhibitions that have been held at the European capitals and in Philadelphia. The subject is one of much interest, in an economical sense, and in the relation it bears to the development of early civilization. Men's first steps in civilization may be traced almost directly in their efforts to clothe themselves; and their first essays in skilled labor are made in the adaptation of the materials which nature has furnished them to use for dress. On the banks of the White Nile are tribes who content themselves with simple aprons of leaves, or less; and Sir Samuel Baker noticed that a great advance in general civilization had taken place when, after having spent several months among peoples of that grade, he came into Unyoro, where the people wore garments fashioned out of the bark of a fig-tree, which they had to prepare by soaking and beating with a mallet. Thrift seemed to follow naturally upon the acquisition of the taste for clothing, for the fig-trees have to be cultivated to secure a sufficient supply. Accordingly we are told, when a man takes a wife, he plants a certain number of the trees in his garden, as a provision for the wants of the family he has in prospect. A grade above the naked races are the Papuans of New Guinea, with their loin-girdles of grass or palm-