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THE POPULAR SCIENCE MONTHLY 



Opium-Smoking in America and China. A 

 Study of its Prevalence and Effects, by H. H. 

 Kane, M. D. New York : G. P. Putnam's Sous. 

 1882. Pp. 156. $1. 



Elements of Orthoepy, consisting of the most 

 Essential Pacts and Principles. By C. W. Lari- 

 son, M. D. Published by the author at Bingoes, 

 New Jersey. 1881. Pp. 132. 



Sewer-Gases : Their Nature and Origin, and 

 how to protect our Dwellings. By Adolfo de 

 Varone, A. M., M. D. Second edition. Revised 

 and enlarged. New York: D. Van Nostrand. 

 1882. Pp.'145. 50 cents. 



Books of All Time. A Guide for the Purchase 

 of Books. Compiled bv F. Leypoldt and Lynde 

 E.Jones. New York: F. Leypoldt. 1882. Pp. 

 80. 



A Reading Diary of Modern Fiction. Con- 

 taining a Representative List of the Novels of 

 the Nineteenth Century, etc. New York: F. 

 Leypoldt. 1881. Pp. 150, with blanks. 



The Actual Lateral Pressure of Earth-works. 

 By Benjamin Baker, M. Inst. C. E. New York : 

 D. Van Nostrand. 1882. Pp. 180. 50 cents. 



The Mother's Guide in the Management and 

 Feeding of Infants. By John M. Keating, M. D. 

 Philadelphia : Henry C. Lea's Son & Co. 1861. 

 Pp. 118. $1. 



POPULAR MISCELLANY. 



Fifty Years' Study of the Distribution 

 of Plants. Sir J. D. Hooker devoted his 

 address, as President of the Geographical 

 Section of the British Association, to a re- 

 view of the progress that had been made 

 during the last fifty years in the study of 

 the geographical distribution of living (par- 

 ticularly of vegetable) forms. The germ of 

 this study is to be found in an idea attrib- 

 uted by Humboldt and Forbes to Tournefort, 

 that in ascending mountains the vegetation 

 gradually approaches that of the higher lati- 

 tudes. Humboldt began his botanical stud- 

 ies early in life, and in his " Prolegomena," 

 published in 1815, endeavored to determine 

 the proportions which the species of certain 

 large families, or groups of families, bear to 

 the whole number of species comprising the 

 floras in advancing from the equator to the 

 poles, and in ascending high mountains. He 

 observed that some kinds of plants increase 

 relatively to others in going from the equator 

 to the poles, others diminish, while some are 

 strongest in the temperate zones, decreasing 

 in both directions. No material advance was 

 made, however, toward improving the laws 

 of geographical distribution so long as it 

 was believed that the continents and oceans 

 had experienced no great changes of surface 

 or climate since the introduction of the ex- 

 isting assemblages of animals and plants. 



This belief was dispelled by Lyell, who 

 showed, from the examples of Sicily and some 

 of the mountain-regions of Italy, that a fauna 

 may be older than the land it inhabits. Dar- 

 win conceived the same idea from compari- 

 sons of the living quadrupeds of Asia and 

 America ; and it was confirmed by the dis- 

 covery of Arctic plants on the mountains of 

 the temperate zone. The first attempt to 

 press the result of geological and climatal 

 changes into the service of botanical and 

 zoological geography was made by the late 

 Edward Forbes, who communicated to the 

 British Association a study of the distribu- 

 tion of endemic plants, particularly those 

 of the British Islands, considered under this 

 aspect. This paper shows that Forbes was 

 profoundly impressed with the belief that 

 the conditions of geological connection and 

 climate were the all-powerful controllers of 

 the migrations of animals and plants, and 

 induces Professor Hooker to pronounce its 

 author " the reformer of the science of geo- 

 graphical distribution." Before the doc- 

 trine of the origin of species by variation 

 and natural selection was published, all rea- 

 soning as to the distribution of species was 

 subordinated to the idea that they were per- 

 manent and special creations. The modes 

 of dispersion had been traced, but the origin 

 of representative species, genera, and fami- 

 lies, remained an enigma. The existence of 

 the same kinds in different places could be 

 accounted for only on the supposition that 

 these different places presented conditions 

 so similar that they favored the creation of 

 similar organisms ; and this failed to ac- 

 count for identities occurring where there 

 was no discoverable similarity of physical 

 conditions, and their failing to occur where 

 the conditions were similar. Under the 

 theory of modification of species after mi- 

 gration and isolation, the representation 

 of similar species in distant localities is only 

 a question of time and changed physical 

 conditions. New data for the study of the 

 past and present physical geography of the 

 globe were afforded by the discovery in 

 the Arctic regions of fossil plants of types 

 corresponding with those which are now 

 found only in warm temperate zones, which 

 dates from 1848. These fossils proved not 

 only to belong to genera of trees common 

 to the forests of all the three northern con- 



