THE POPULAR SCIENCE MONTHLY. 



Smithsonian Institution. Annual Report of the 

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Sohn, C. E. Dictionary of the Active Principles 

 of Plants. Philadelphia: J. B. Lippincott Co. 

 Pp. 194. $3. 



Spencer, J. W., State Geologist. Geology of 

 Ten Counties of Northwestern Georgia. Atlanta. 

 Pp. 406, with Map. 



Spencerian System of Penmanship. Common 

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 Business Forms. Parts VIII, IX, and X. Ameri- 

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Tales from Town Topics, No. 11, March, 1894. 

 New York: Town Topics Publishing Company. 

 Pp.240. 50 cents. 



Thorpe, T. E. Essays in Historical Chemistry. 

 New York: Macmillan & Co. Pp. 381. $2.25. 



University Review, January, 1894. New York: 

 University Review Company. Pp. 74. 25 cents. 



Veeder, M. A., M. D., Lyons, N. Y. The 

 Source of Solar Heat. Pp. S. 



Vines, S. H. A Student's Text Book of Botany. 

 New York: Macmillan & Co. Pp. 430. $2. 



Walker, Francis A. Bimetallism: A Tract for 

 the Times. Boston. Pp. 24. 



Ward, Lester F. Status of the Mind Problem. 

 Washington. Pp. 18. 



Webb, The Rev. T. W. Celestial Objects for 

 Common Telescopes. Vol.1. New York : Long- 

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Welcome, S. Byron. From Earth's Center. 

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Whitman, C. O. Biological Lectures delivered 

 at the Marine Biological Laboratory of Woods 

 Holl, 1893. Boston: Ginn & Co. Pp. 242. $2.15. 



Wright, G. F. Continuity of the Glacial Pe- 

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POPULAR MISCELLANY. 



Reptilian and Amphibian Motions. M. 



Marey has extended his time-photographic 

 studies of locomotion to mammals, birds, 

 reptiles, fishes, and articulates. The pro- 

 cesses are rather difficult, because they have 

 to be applied to a great variety of move- 

 ments, and of methods and habits of carry- 

 ing them on ; but it is nearly always possi- 

 ble to assure satisfactory representations by 

 adapting the methods of working to the con- 

 ditions. The chief difficulty is in getting the 

 animal experimented upon to go at its ordi- 

 nary gait. This is much more easily accom- 

 plished with domesticated animals than with 

 wild ones. By comparing the types which 

 he has got represented, M. Marey discovered 

 some very interesting analogies. Thus, in 

 locomotion on land and on water, he was 

 able to follow the gradual transition between 

 simple "reptation" and the most compli- 

 cated kinds of locomotion. An eel and a viper, 

 put in water, advance in the same manner; 

 a wave with lateral inflections runs continu 

 ously from the head to the tail of the animal, 

 and the velocity of the retrograde movement 



of the wave is much greater than the speed 

 of translation of the animal. If the animals 

 are set upon the ground, the mode of repta- 

 tion will be modified in both in the same way. 

 The amplitude of the undulatory movement 

 from one side to the other will be greater, 

 and will increase as the surface on which the 

 animal creeps is smoother. A vestige, more 

 or less pronounced, of the undulatory reptil- 

 ian movement remains with fish that have 

 fins and reptiles endowed with legs. In the 

 sea-dog, for instance, the retrograde wave 

 running along the whole body is very pro- 

 nounced. It is considerably reduced in the 

 salmonides, and does not appear except at 

 the tail in fishes the bodies of which are 

 more stubby. This retrograde wave is plain- 

 ly manifest in the gecko, but less so in some 

 other lizards. The analysis of the varieties 

 of locomotion of the batrachians in the dif- 

 ferent stages of their evolution is very inter- 

 esting. The tadpole, for example, exhibits 

 in its earliest stage progression by the undu- 

 lation of the caudal fin; a mixed type of 

 locomotion comes in with the paws ; the tail 

 continues to wriggle, and the hinder limbs 

 make the swimming motions appropriate to 

 them ; and the latter movements exist alone 

 for some time after the tail has disappeared. 

 These motions, which so much resemble 

 those of man's swimming, present the pecul- 

 iarity of the fore legs having no part in them, 

 and of the hind legs, after having been sepa- 

 rated so widely as to form a right angle with 

 the axis of the body, approaching one an- 

 other till they become parallel, then bending 

 and spreading out again to begin a new 

 spring. The motions of lizards' legs are so 

 swift as to escape direct observation, but the 

 successive movements of the fore and hind 

 limbs can be followed in photographs taken 

 forty or fifty times a second. The normal 

 gait of the lizard and the gecko is the trot 

 that is, their limbs move diagonally. The 

 great amplitude of the motions, combined 

 with the undulation of the axis of the body, 

 causes the limbs on the same side to come 

 very near one another, and then separate 

 widely in the following instant. The lizard 

 projects its hind foot nearly into its armpit 

 on the side on which the body becomes con- 

 cave ; an instant afterward that side becomes 

 convex, the fore leg is carried far forward, 

 and, the body forming a convex arc on that 



