BEHAVIOR OF VERTEBRATES 409 



the water and its effects upon the movements, migrations and 

 general health of the animals. We should know more of the 

 chemical conditions in which the animals breed in order to secure 

 the preservation of their natural breeding grounds against the 

 contamination which follows as a result of advancing civiliza- 

 tion and industry. The study is extremely suggestive as to the 

 physiological explanation of the migration of fishes, etc. The 

 economic value of such work is not sufficiently appreciated. 

 The authors say: — " The extreme sensitivity of the fishes studied 

 as shown by their detection of slight deviations from neutrality, 

 of temperature differences as small as .2 of a centigrade degree, 

 of small fractions of a cubic centimeter per litre of hydrogen 

 sulphide, etc., makes it very clear that there is no difficulty in 

 fishes determining the direction to large rivers from hundreds 

 of miles out at sea or finding their way into any bay or harbor 

 which their particular physiological condition at the time 



demands." 



OLFACTION 



Mammals. — The only article dealing exclusively, or predom- 

 inately perhaps one would better say, with olfaction in animal 

 life is one by Seffrin (24). This investigation attempts to find 

 odorous substances and the necessary amounts of each to cause 

 a reaction. The registration of these reactions was by means 

 of the breathing movements, — -a method previously used in 

 similar experimentation by Heitzenroder. The apparatus and 

 method are fully described. He used such substances as ether, 

 formaline, xylol, oil of rose, violet, extract of vanilla, etc., and 

 also mixed odors of animal origin, — urine, blood, flesh extracts, 

 etc. He found the dog less sensitive than man to the first class 

 of odors but far more so to those animal odors more closely re- 

 lated to his life. Tables are given showing the amount of the 

 stimulus and the time of the reaction. 



VISION 



Mammals. — In a paper included in the transactions of the 

 Illuminating Engineering Society, Johnson (16) reports, with 

 clear comments, some recent experiments of his own and others 

 in the field of animal vision. De Voss and Ganson (8) publish 

 some work on the color blindness of cats. They say: — " The 

 term ' color blindness ' is used in the title of this paper not 



