256 Scientific Intelligence. 



their natural level; for the changes in the former would be due 

 not only to altitude but in great part to the transplanting and 

 acclimatization in new situations. Differences of soil, exposure, 

 encroachment of neighboring plants and other such factors would 

 of course introduce like inaccuracy into the results. Professor 

 Bonnier's ingenious methods of avoiding these difficulties have 

 been in brief as follows : 



The root or base of a plant has been taken from a medium 

 altitude and divided into two equal parts, one of which was 

 transplanted to a higher altitude, the other to an equal distance 

 below its original position under similar conditions of exposure. 

 In this way the disturbing influence of acclimatization is lessened 

 by half; while as both plants are removed from their original 

 situation the effect of transplanting may be presumed to be 

 equal in both cases. The plants have in all instances been placed 

 in soil brought from the spot from which they were taken. The 

 species selected for experimentation have been mostly such as 

 were spontaneous in the regions where they were cultivated; and 

 lastly no comparisons have been made until the plants have be- 

 come so far acclimatized in their new situations as to bloom and 

 bear fruit. Professor Bonnier has made over two hundred such 

 cultures, choosing his plants from widely different orders. Some 

 of the cultures were begun as early as 1884, and more than half 

 were still alive at the time of writing. The observed effects of 

 high altitude upon the growth of phaenogams have been a smaller 

 form, shorter internodes, a comparatively large development of 

 subterranean parts, leaves smaller, thicker, and brighter green, 

 and flowers more highly colored. Some of these traits vary di- 

 rectly with the altitude, while others, as the greenness of the 

 leaves, have been observed to reach an optimum at a certain 

 height, beyond which the plants in these regards come more or 

 less to resemble specimens growing at lower levels. Certain 

 plants, as Chenopodium Bonus-Henricus, appear to undergo little 

 or no modification for differences of altitude. b. l. r. 



5. Insecta ; by Alphetjs Hyatt and J. M. Arms. — Guides 

 for Science Teaching, No. viii. Boston Society of Natural His- 

 tory, pp. i-xxxiii, 1-300, 223 illustrations, 1890. — The methods 

 upon which this work is based will recommend themselves to 

 students and teachers, as they furnish a philosophical account of 

 the various members of the class and of the formation and inter- 

 dependence of the various organs and functions of the organism. 

 The characters of Thysanura represent the key to the system of 

 modern classification, and the Thysanuran stock is taken as the 

 primitive type from which have been derived the present sixteen 

 orders of insects. A phylogenetic arrangement, illustrated 

 graphically by diverging and parallel bars, expresses in a satis- 

 factory way the relations of the orders, while a plane at right 

 angles to the axial stock represents the surface of the earth. The 

 authors conclude that the thorax is primarily a three segmented 

 region, and has become modified into greater complexity by 



