ee ee Se 
1909] CURRENT LITERATURE 65 
eyes when the sun is low. As the red Florideae are colored in complement to the 
green-blue rays least weakened by traversing sea water, so the green and yellow 
of chlorophyll are complementary to the red and blue that traverse the atmospheric 
sea. It thus appears that the yellowish green of vegetation is really an adaptation 
to the composition of diffuse light. 
Various lines of reflection, more or less closely related to this idea, are elab- 
orated, such as, Regulation of the absorption of the sun’s rays; Variable content 
of chlorophyll in nutritive organs; Biology of non-green algae; Etiolation, 
autumnal yellowing, and their biological significance. 
The book is almost purely philosophical, only a few experiments, and these 
avowedly superficial, being recorded. Of course the general thesis does not 
touch the fundamental reason for plant coloration, and it is doubtful whether there 
is any logical gain in this mode of looking at the facts. To give it validity, it must 
be shown that the absorption of other rays by different pigments (and consequently 
a different colored vegetation) would be nutritively inefficient. Considering the 
fact that most plants get far more energy than they can use at ordinary tempera- 
tures, by reason of the inadequate supply of CO., it would surely be difficult to 
show this —C. R. B 
MINOR NOTICES 
Bacterial classification.—JENSEN has attacked the difficult problem of bac- 
terial classification with a view to making a ‘‘natural system,” that is, one which 
will express relationship by descent. Most attempts to classify bacteria have 
been based first upon form or upon mode of cell division, and then upon physio- 
logic characters. This m@thod has led to many anomalies. For example, in one 
sharply defined family, the red sulfur bacteria, there are found rod, spiral, and 
round forms; and in the case of certain species of Crenothrix and Azotobacter, 
division occurs first in one, later in three planes. JENSEN argues that bacteria 
ag a “ae Bagelbum, 0 or pane as of polar flagella, are closely allied, but that 
well as other reactions from those 
tie hasell dintributed over ie cell-body. Hence he divides the whole bacterial 
kingdom into two orders: (1) Cephalotrichinae and (2) Peritrichinae. In the former 
he groups seven families, in the latter four families. For genera he selects, as a 
means of discrimination, the oxidizing, reducing, fermentative, and other chemical 
_ processes of metabolism, as shown by the work of himself, WINOGRADSKY, 
_ Betyerrnck, Kaserer, Burri and StitzER, MoLiscH, OMELIANSKI, BUCHNER, 
_ and others. JENSEN regards the genus Methanomonas as the origin of all organic 
_ life, since this autotrophic, monotrichial, rodlike form builds up its cell substance 
_ in the simplest manner possible, without requiring either organic carbon, organic 
nitrogen, or outside energy such as light or heat. On the contrary, a certain 
° JENSEN, O., Die Hauptlinien des natiirlichen Bakteriensystems nebst einer 
‘ Uebersicht der Girungsphinomena. 8vo. pp. 42. fig- I. Jena: Gustav Fischer. 
3 M 1. 
1909. 
