REVIEWS, BOOK NOTICES, ETC. 24I 



physiology, general ecology and etiology, it is written from a genetic 

 standpoint, so that the w^a/wV/^ of structures or phenomena discussed 

 is at once apparent. Moreover, not only are the latest discoveries 

 in botanical work, recent or fossil botany, referred to, but many of 

 the more important zoological facts are contrasted with them. It will 

 illustrate the scope of the work best perhaps to refer to a few of these. 

 In connection with the origin of life, Winogradsky's researches on 

 nitrogen bacteria are mentioned. In discussing the lower plants, 

 Bower's theory of sterilisation finds a place, and the antithetic 

 alternation of generations of pteridophytes and bryophytes is 

 affirmed. 



In relation to heredity, F. Darwin's views on memory are accepted, 

 and, we think, with good reason. Bower's theory of sterilisation is 

 however, not accepted, an entirely separate origin for the sporophyte 

 in club-mosses and ferns being assumed. Researches amongst the 

 carboniferous and mesozoic floras as to the origin of seed plants by 

 Scott, Seward, and Wieland are given due prominence. By the way, 

 Seward's view that conifers such as Araucaria are related to the 

 Palaeozoic lycopods is favoured. The cumulative effects of stimuli 

 are illustrated by Jenning's work on Infusoria. In determining the 

 value of current theories of the origin of species, the mutation theory 

 of De Vries and Mendel's laws of heredity are fully discussed, but 

 Lotsy's views as to the cause of mutations are preferred, the germ- 

 plasm theory, in so far as plants are concerned (since they are more 

 plastic and respond to external stimuli more readily), not being con- 

 sidered to apply. The nature of the Palaeozoic climate is explained 

 on Manson's view that a mantle of cloud excluded sunlight. Great 

 stress is laid upon Kleb's experiments as to the effect of stimuli in 

 determining sex and regulating other factors of the environment. 

 All the important results of plant breeders bearing on the questions 

 discussed are surveyed, and Bailey and Burbank are cited here. 

 Winckler's work on graft hybrids also receives adequate notice. 



The book is divided into ten chapters, including an introduction, 

 the factors in evolution ; the lower plants ; the origin of land plants 

 (which are derived from green algje) ; seed plants, leading on from 

 heterospory in pteridophytes from the zygote or resting stage in 

 algae required by dry conditions ; the Angiosperms, where the division 

 into monocotyledons and dicotyledons is regarded as artificial, and 

 their characters considered as adaptive, developed in parallel series ; 

 environment and adaptation, the terrestrial phase being the cause of 

 seed plants, and their possession of fruit is regarded as the cause of 

 their dominance. The chapter on plant distribution is especially 

 interesting and will appeal particularly to American students. The 

 human factor in plant evolution is dealt with from an original out- 

 look, and the great importance of extinction is adequately recognised. 



The origin of species is lucidly expounded, and it is justly re- 

 marked that plants differ from animals in this respect, for while the 

 germ-plasm may play a part in the case of the latter, in the case of 

 plants, "to assume that there is a special germ-plasm, which is passed 



VOL. I. 18 



