540 BOTANICAL GAZETTE [DECEMBER 
Many investigations have been made on the so-called influence of various 
environmental factors on the production of pigments by fungi, but a survey of 
the facts seems to indicate that between the absorption of an elementary 
nutrient and the production of a complex pigment two processes intervene to 
permit of the establishment of a direct relation between stages at the extreme 
ends of the series. A much better knowledge than is at hand at present of the 
nature and structure of fungous pigments is necessary before their physio- 
logical status can be determined. Different colors may often be due to the 
modification of the same pigment, depending on different reactions of the 
medium.—H. HASSELBRING. 
Origin and goal of geobotany.—Rtset’ has issued a compact and useful 
paper, dealing with the main phases of the development of geobotany and with 
the aims of its various subdivisions. Geobotany he regards as embracing all 
interrelations between plants and the earth, including much of ecology, cho- 
rology, chronology, and genetics; thus it includes all of phytogeography in the 
widest sense, and more. The historical presentation deals especially with the 
work of THEOPHRASTUS, TOURNEFORT, LINNAEUS, HALLER, SOULAVIE, WILLDE- 
now, HumBoLtpt, WAHLENBERG, and ScHouw. Geobotany may be either 
floristic or vegetational, each of which subdivisions may consider the problems 
of space (distribution), habitat (ecology), or change (genetics). Thus RUBEL 
recognizes 6 fields of geobotany: autochorology, or floristics; synchorology, or 
the distribution of plant associations; autecology, or the relation between the 
individual and the habitat; synecology, or the relation between the plant asso- 
_ ciation and the habitat; ra or the change of floras; and syngenetics, 
or the change of plant associations. It appears to the reviewer that this is the 
most logical classification of dese fields of study with which he is familiar. 
As a matter of practice, however, it is unlikely that investigators will increas- 
ingly recognize such subdivisions. A treatise dealing only with synchorology 
was fairly satisfactory in times gone by, but in these days it would seem sterile, 
except as livened up with ecology and genetics.—H. C. Cow Les. 
ontinuous variation.—Stout and Boas,’ as the result of their extensive 
statistical studies of variation in Cichorium, recommend that critical study of 
species variation should be based upon intensive studies of partial (existing 
among the parts of a single individual) and individual (characteristics of plants 
as wholes based on their entire record) variabilities. They suggest that failure 
to appreciate this necessity has allowed considerable error to creep into the 
work of a number of investigators. For example, hereditary studies of such 
* Riser, Epuarp, Anfinge und Ziele der Geobotanik. Vierteljahrsschrift der 
naturforschenden Gesellschaft in Ziirich 62:629-650. 1917. 
9 Stour, A. B., and Boas, HELENE M., Statistical studies of flower number per 
head in Cichorium Intybus: kinds of variability, heredity, and effects of selection. 
Mem. Torr. Bot. Club 17:334-458. pls. 10-13. 1918. 
