328 BOTANICAL GAZETTE [APRIL 
species there is usually a further subdivision into such topics as land form, 
water form, submersed form, form with floating leaves, etc. The greater part 
of the work is taken up by the plants of the water margin (“‘zone 2”). These 
belong to two categories, so far as leaf form is concerned, those that are homo- 
blastic or with but one leaf type, and those that are heteroblastic or with two 
leaf types; the heteroblastic water plants are with us well represented by such 
plants as Siwm and Proserpinaca. Most of the plants of ‘zone 1”’ have greatly 
reduced water forms, many of which are generally unfamiliar, and some of 
which are known only from cultures; these forms rarely flower. One of the 
striking discoveries is a water form of a dodder (Cuscuta alba) which parasitizes 
Isoetes and water buttercups. Only a few of the species studied live in flowing 
water. The water forms seem related to low temperatures, and while the land 
form is essentially a summer form, it can sometimes be produced at other 
seasons by raising the temperature of the cultures. Most of the species have 
winter rest periods, but there are some species that vegetate continuously, even 
in countries with cold winters. Many Mediterranean species have periods of 
summer rest. These and many other topics are considered in the 40-page 
summary with which the volume concludes. The book should be in every 
botanical reference library, for it will serve as a compendium of general ecologi- 
cal information about the plants it treats. It is understood that Dr. Giiick is 
devoting his life to the study of water plants, and we may expect other volumes 
of this sort in the future—Henry C. Cow es. 
Plant breeding in Sweden 
The extensive series of experiments in plant breeding which have been 
conducted in Sweden, principally at the Svaléf station, beginning about 1886 
and extending with ever increasing efficiency to the present time, are of great 
interest not only to agriculturists but also to scientists by reason of the prob- 
lems of inheritance which they involve. Unfortunately very scanty reports 
of these operations have been available in any but the Swedish language, and 
these publications have been, and quite rightly so, most largely concerned 
with practical results that were of special interest to the farmers of Scandinavia. 
These circumstances will make the present report? the more useful, prepared 
as it is by one who has carefully investigated the methods employed and the 
results obtained at the Swedish stations, and addressed primarily to the scien- 
tific reader, but in language intelligible to the general public. 
e report contains a brief historical sketch of the inception and develop- 
ment of plant breeding experimentation in Scandinavia, examples of the experi- 
ments with different agricultural plants, some of the results obtained, and a 
summary of the principles now recognized by the plant breeders at Svaléf 
and followed in their work. These principles are briefly: (1) the recognition 
3 NewMaN, L. H., Plant breeding in Scandinavia. 8vo. = 193. figs. 63. Ottawa, 
Canada: Canadian Seed Growers’ Association. 1912. $1. 
