tg2t] CURRENT LITERATURE 405 
_ Teviewer is ready to agree with his conclusion that “the watchwords of a 
rational and reasonable ecology are logic, common sense, and physiological 
experimentation,” and perhaps to echo his “We do not need their cpio 
“9 their abominable nomenclature; we have enough of our own.” —GEo 
ULLER. 
Alpine adaptations.—In 1884 BONNIER began his classical experiments 
upon the structural changes induced by growing plants at various altitudes. 
Plantations were made in the lowlands and at various altitudes in the Alps, 
So arranged that the two individuals to be compared were produced by divid- 
ing one plant. Similar experiments were begun in the Pyrenees in 1886, and 
the botanical world is familiar with the remarkable results as reported in 
Bonnter’s earlier publications. Now after a lapse of over 30 years he makes 
a Summary of what are probably the most notable and proerecs experiments 
of their kind on record.” 
A few of the plants taken from the plains to alpine stations died, but a 
list is given of 58 species that proved able to maintain themselves at high 
altitudes. These have all undergone changes which make them closely 
resemble indigenous alpine plants. The principal changes are relatively large 
development of the subterranean as compared with aerial parts, shortening of 
the leaves and of the internodes of stems, increased hairiness, and relatively 
larger development of bark and protective tissue. The leaves became thicker in 
proportion to their surface and are a deeper green, with more highly developed 
Palisade tissue and a larger number of chloroplasts, while the flowers are larger 
and more highly colored. In at least 17 species the changes are so great that 
the plants have apparently been transformed into distinct alpine “species. 
Thus Lotus corniculatus L. began to show decided modifications within 10 
years, and finally became identical with L. alpinus Schleich; Helianthemum 
vulgare Gaertn. has in 30 years become H. grandiflorum vse while Leontodon 
proteiformis Vill. in 6 years is completely transformed into L. alpinum Vill. 
For all the species able to maintain themselves ais considerable alti- 
tudinal range, there seems to be an optimum altitude at which the transfor- 
mations are most rapid, most complete, and where intensity of color and 
development of chlorenchyma reach a climax. Species of Potentilla may be 
cited as indicating individual differences of range. Thus the optimum con- 
ditions for P. argentea appear to be found at 1050 m., for P. repians at 1500 m., 
and for P. tormentilla at about 2000m. Cultures of alpine plants at lower 
altitudes showed reversed although less marked transformations. Alpine 
species, able to maintain themselves at various altitudes, at the lower stations 
gradually lost many of their typically alpine characteristics, and a list of 14 
species showing such changes is given. Certain annuals taken from the 
° BONNIER, GasTON, Nouvelles observations sur les cultures expérimentales a 
diverses altitudes et cultures par semis. Rev. Gén. Bot. 32:305-326. pls 2. figs. 4. 
1920. 
