432 BOTANICAL GAZETTE [JUNE 
as resulting from PAasTEuR’s work on spontaneous generation. An insight is 
given into the relations of molds, fungi, bacteria, and yeasts to each other, with 
an outline of their general morphology and classification. Modern methods of 
cultivation and the introduction of pure cultures in fermentation industries and 
dairies are discussed. A short chapter is devoted to the activity of bacteria in 
the soil and their relation to agriculture. Considerable space is finally devoted 
to pathogens, and the spread of infectious and contagious diseases. Advice and 
methods are given as to their prevention and treatment. A number of illustra- 
tions elucidate the text. The whole book represents a good summary of our 
present knowledge of micro-organisms in a concise, popular style-—P. HEINE- 
MANN. 
GoEBEL"+ has investigated the cleistogamous flowers of a variety of plants 
from the point of view especially of the adaptation theory, and presents an inter- 
esting account of the external condition under which these occur in nature, or 
can be made to occur in culture. It appears that a large number of plants have 
the ability to produce cleistogamous instead of chasmogamous flowers under the 
aig of certain external conditions. Contrary to the belief of Darwin and 
, GOEBEL shows that there is no causal connection between the absence of 
festa. or the formation of seed, and the appearance of cleistogamous 
e latter is due to insufficient food relations, and this may arise from 
poor soil, a lack of mineral constituents, or insufficient light. In many plants 
the cleistogamous flowers do not set seed. In these cases the appearance of 
cleistogamous flowers is not due to the suppression of seed-formation, but GOEBEL 
thinks the seed-formation is suppressed by the appearance of cleistogamous 
flowers.—W. B. McCativum. 
Motiscu's has reported convincing evidence that stems of certain seedlings 
respond with positive curvatures when exposed to rays emanating from sealed 
tubes containing a mixture of radium and zincsulfid. The seedlings should be 
less than 7™ distant from the tubes and preferably about 2°™. Tubes con- 
taining radium bromid only (activity 3000) fail to give positive results, as pre- 
viously found by Drxon. When radium bromid and zincsulfid are mixed, 
cage a steady phosphorescence of considerable intensity develops, due to 
the influence of the radium on the zincsulfid. Moriscu therefore regards the 
curves pianist as heliotropic, indirectly induced by radium. The interesting 
fact is also recorded that while such experiments succeed in the laboratory they 
usually fail in the greenhouse. The author believes that the illuminating ges 
and other volatile impurities in laboratory air reduce the negative geotropism, 
thereby increasing sensitiveness to phosphorescence and heliotropic stimulus.— 
Raymonp H. Ponp 
4GorBEL, K., Die kleistogamen Bliiten und die Anpassunpstheorie. Biol. 
Sc a ene etc. 1904. 
1s Moriscu, Hans, Ueber ii ens indirekt hervorgerufen durch Radium. 
Ber. Deutsch. Bot. Gesells. 23:2-7. fig. I. 1905. 
