250 The Plant World. 



habit, for example, of relying implicitly on the stimuli of 

 light and gravity. l>y responding to these stimuli, it 

 finds its proper place with such certainty (hat other mode ; 

 of response to other stimuli are ignored habitually." 



By means of isolation and sterilization the author \v;is 

 able to prove that the green cells in the Convoliita oripiiiaie 

 from a free swimming alga, one of the clamydomonads, 

 v.hich infects the larvae soon after hutching. He raise 1 

 colorless larvae but found that they went to pieces long ].c 

 fore maturity, indicating that these animals are depe ide.sr 

 upon the algae for essentials in their food supply and f,)r 

 the elimination of nitrogenous wastes, the excretory sys- 

 tem being entirely lacking. 



The algae when free have a cell wall, four flagellae, a 

 nucleus, a pyrenoid, an eye-spot and several ch]oroplast>. 

 All of these except the chloroplasts degenerate and disap 

 pear after existence in the larvae for a few generations. 

 This the author thinks lends support to the suggestion of 

 Schimper and Lankaster that the chloroplasts in the higher 

 plants originated by the degeneration of symbiotic algae. 



The book as a whole is verv interestins: and well worth 

 while, but I cannot forbear entering a protest against ex- 

 pressions such as the following, which, in the mind of the 

 present writer are neither popular nor scientific and serve 

 only, especially in the layman's mind, to mystify Avhat 

 actually occurs in the responses of these organisms. 

 "They phototrope themselves to the light," p. 64 ; "It takes 



the hint and photrotropes," p. 70 ; "Vibrations 



troping," p. 67.— S. O. Mast. 



Vegetation IN THE Alps. — Riibel has published * the results 

 of an extended study of the climate and vegetation of the Ber- 

 nina Valley and its adjacent peaks, in the upper Engadine region 

 of the Alps. The author lived for over one year at the Hospice 

 of Bernina and carried on personally the principal part of his 

 instrumentation, at the same time that he used for compari- 

 son all reliable climatological records for his region. The 

 Hospice of Bernina is at an altitude of 7,S78 feet; (2,309 m.) 



•Riibel, E.. Pflanzengeograohische Monographic des Beminagebietes. Botan. Jahrb.. 47 

 1, pp. 1-296; 36 plates and map; 1911. 



