140 BOTANICAL GAZETTE [FEBRUARY 
books of COULTER or BERGEN. It is refreshing to miss the old familiar cuts that 
have done service for so long. Not only do the photographic reproductions 
represent South African scenes, but even the diagrams and cuts are made from 
South African plants, and for the most part especially for this book. The first 
chapters deal with seeds and germination, growth and duration of the vegetative 
organs, and various fundamental physiological topics. The chapter on plant 
defenses is illustrated by some of the remarkable desert xerophytes of the region, 
such as Crassula and Mesembryanthemum. Then follow chapters on vegetative 
reproduction, climbing plants, and migration. After a rather full consideration of 
flowers and fruits, there is a simple but useful key to the more conspicuous plants 
of the region. The old-fashioned order of BENTHAM and HooKER is used in the 
classification, but this is probably justified by the fact that South African syste- 
matic works have followed the BENTHAM and HooKkER scheme. The 
should do its part in making botany in the schools a more living and attractive 
subject.—HeEnry C. Cow Les 
MINOR NOTICES 
Spontaneous heating.—The ‘“‘heating” of hay and compost heaps has been 
an interesting biological phenomenon as to whose causes many were content to 
reason, but few to experiment. MIreHE recently published a scientific summary 
of his work, which is now followed by a booklet, addressed to a wider audience.’ 
It embodies his own investigations for the past two years, to which are added the 
facts already known, so as to make a complete discussion of this subject, which 
is of both biological and practical interest. 
The topics treated are: The course and maximum of the rise of temperature; 
chemical changes in the heating of compacted hay with exclusion of oxgyen; 
cause of heating; culture substrata and researches with pure cultures; descrip- 
tion of the nine most important organisms found in hay; self-sterilization by 
heating; the conditions of existence of thermophilous organisms in nature; heat- 
ing plant materials as brood-beds for pathogenic organisms; relation of the 
fermentation of tobacco to the heating of hay; respiration and warmth; heating 
and spontaneous combustion, present and past. 
will be particularly useful to men in experiment stations who are 
concerned with this problem, as it forms an excellent summary of present knowl- 
edge. It is handicapped by lacking an index, though it has an exhaustive bib- 
liography. af. RH, 
The origin of species and varieties by mutation.—It is an encouraging sign 
when such a scientific treatise as Professor DEVrRIES’ Species and varieties comes 
to a second edition within one year. Probably no work on evolution written in 
7 MrexE, Huco, Die Selbsterhitzung des Heus. 8vo. vi+127. figs. 11. Jena: 
G. Fischer. M 3250. 
8 DeVrigs, Huco, Species and varieties; their origin by mutation. wag by 
The 
D. T.. MacDoucat. sep edition. 8vo., pp. xviiit+847. Chicago: 
Court Publishing Co. 
