174 Literary Notices. 



Lyon, E. P. Rheotropism in Fishes. Amer.Jour. of Physiol., Vol. 12, pp. 149-161. 1904. 



By a series of very simple experiments the author has proved that the orienta- 

 tion of fishes in currents of water is due to a great extent to visual stimuli, and far 

 less than is usually supposed to cutaneous stimulation. "I am convinced," writes 

 Dr. Lyon, "that with the fishes experimented with orientation in currents of fairly 

 uniform velocity is usually an optical reflex. The current does not directly stimu- 

 late. Indirectly it does, by tending to move the fish away from the fixed points of 

 its environment." 



Experiments with fish in stationary vessels about which the environment was 

 moved, and with blinded fish prove conclusively that sight is of heretofore unsus- 

 pected importance in the so-called rheotropic reactions. Contact with solids in- 

 fluences the reaction, but the author believes that "pressure results from orientation; 

 it does not produce it." 



The paper is a valuable contribution to the literature on tropisms. 



R. M. Y. 



Towle, Elizabeth W. A Study of the Effects of Certain Stimuli, Single and Combined, upon Para- 

 mecium. Amer. Jour, of Physiol. ,Yo\. 12, pp. 220-ZT,6. 1904. 



This investigation of the effects of stimuli upon the form and condition of 

 Paramecium serves chiefly to emphasize, as the writer points out, the importance 

 of the large number of unknown factors with which we deal in all our studies of 

 animal reaction. The facts indicated in the paper cannot be summarized easily, 

 but perhaps the following sentence will indicate its trend and content: "Finally 

 we are, I think, forced to the conclusion that the terms 'coagulation' and 'lique- 

 faction' at present serve largely to cover our ignorance, for they express only in the 

 vaguest way the processes that take place in living organisms in response to dif- 

 ferent stimuli. The retarding influence of lowered temperature, the secondary 

 effects which take place in certain reagents, and the appearance of new phenomena 

 when mixtures of subfatal solutions are used . . . point to the occurrence in 

 the protoplasm of extensive changes which we cannot now fully analyze." 



R. M. Y. 



Thauzies, A. L'Orientation du pigeon voyageur. Revue Scientifque, 5 Ser., Vol. 2, pp. 417-420. 

 1904. 



As a lifelong student of the carrier pigeon, Thauzies rejects the theory of 

 E. DE Cyon (L'Orientation chez le pigeon voyageur. Revue Scientifique, 4 Ser., 

 Vol. 12, pp. 353-357, 1900) that nasal sensations partially condition distance 

 orientation, stating that the sense of odor is undeveloped in pigeons. This mis- 

 interprets the author in question, for he says explicitly that he is not thinking of 

 olfactory sensations, but of others arising from the stimulationof the mucous mem- 

 brane by the wind. Thauzies heartily agrees with him, however, in appealing, 

 also, to certain higher physical acts as factors in the process (local memory, choice, 

 etc.), and states that his long experience shows the animal to be of considerable 

 mental development; he believes even that it "observes, compares, reasons, 

 reflects." 



J. e. r. 



