Page:Popular Science Monthly Volume 13.djvu/457

Rh being furnished by women. The difference between the mass of the brain of man and that of the gorilla is proportionally, perhaps, the greatest that exists to separate the two. It has been considered by Huxley to approximate to twelve ounces. But the difference between the extremes of brain-weight in man, as exemplified in the figures here given, shows that we cannot consider intelligence to depend on the weight of the brain. All that we can say is, that a man with a large brain has capacity for the display of intelligence. It depends on his use of the senses, which are the feeders of the intellect, whether he displays high wisdom or not. It is quite possible that an ape may be more intelligent than a human being who has not properly supplied his brain with information. Human beings born dumb and blind are not born ipso facto intelligent, but are taught with great trouble and patience through the channels of the remaining senses. The facts known in regard to afflicted persons are amply sufficient to warrant the statement that the intelligence depends on the senses, and if these are interfered with, either in the structure of the organs, or by giving them a limited opportunity for activity, you have, as a result, less intelligence in the individual, be it man or ape, or other animal. We can show that the difference between man and apes is a quantitative and not a qualitative one.



O manifold are now the uses of photography that we need not dwell upon the importance of processes which allow of the employment of easily-handled apparatus, and which do away with cumbersome and fragile glass plates. Deyrolle's photographic process, described below, answers all the requirements of portability.

The idea of substituting sensitive paper for heavy, brittle plates of glass is not new, but all the processes hitherto offered labor under the serious disadvantage of necessitating a long exposure. Besides, the proofs are usually imperfect on account of the granulations which the paper leaves on the positive. M. Deyrolle's collodionized paper does not present these difficulties. It is covered with a special coating, insoluble in ether, alcohol, or water, and thus it undergoes all the operations of photography without change. This paper is collodionized and treated precisely as though it were glass. It is, in fact, quite equal to glass plate for the uses of photography, and in addition possesses the following advantages:

The layer of collodion is so firmly attached to the coating of the paper that it cannot be injured by contact with a hard object, nor even by slight friction. Besides, the picture can be developed by total 