REVIEWS 509 



genera and families are indicated, whilst considerable prominence is given to 

 economic uses. 



The volume, though forming an invaluable, and, indeed, almost indispensable 

 work of reference for the student and teacher, possesses the inestimable attribute 

 of convenience. 



It is especially true of a work of this character that perfection can never be 

 attained, since, even whilst passing through the press, genera are merged and 

 segregated, new facts are brought to light. It is with a full appreciation of these 

 difficulties that we would call attention to one or two passages where revision is 

 desirable. On page 581 we read that the genus Salicornia is "leafless," a state- 

 ment that is not justified even as a " popular " presentation of the peculiar fusion 

 between stem and leaves that here obtains. Again, in describing the Ranun- 

 culaceae the impression is given that extrorse dehiscence of the stamens 

 characterises the group as a whole, whereas, actually, as pointed out long ago 

 by Baillon, there is in this family almost every gradation between the completely 

 extrorse condition exemplified by Ranunculus and the completely introrse of 

 Eranthis or Pceonia. 



The statement (p. 544) that the prothallus of Psilotum " has not been seen " 

 was perhaps correct when the MS. went to press, though it is now over two years 

 since Lawson's description was published. 



In the article on nomenclature there seems to be an implication that the 

 difference between a form and a sub-variety or variety is one of degree and not of 

 kind, but this appellation should, of course, be restricted to states known or 

 presumed to be due to habitat conditions. 



But the existence of errors is almost inevitable in a work of this character, and 

 it is far easier to criticise than to do adequate justice to its many merits. 



The work is one that should be in the hands of every student, for it belongs to 

 the small class of the well-nigh indispensable. 



E. J. S. 



Vegetable Growing. By J. G. Boyle, B.S., M.S. [Pp. ix + 334, with 154 

 figures.] (Philadelphia and New York : Lea and Febiger, 191 7.) 



THE professed aim of this addition to the numerous works on the culture of 

 vegetables is to show " the connection between principles and practice." There 

 are certainly few occupations where empiricism is more rife, or where the prac- 

 tical man is so often at a loss to explain his success. 



The apparently irreconcilable experiences of acknowledged experts often 

 testifies to a high standard of technique divorced from a corresponding theoretical 

 knowledge. 



It is particularly with respect to the chai-acter of the soil and the use of fertilisers 

 that ignorance of fundamental principles appears most widespread. Unfortunately, 

 in the work before us it is these very subjects which receive but scanty treatment. 

 Artificial manures are dealt with in less than two pages, and the soil, as such, is 

 disposed of in a few paragraphs. The chapter entitled " Insect and Disease 

 Control " occupies seventeen pages, but attempts in this limited space to cover 

 the subjects of animal and plant parasites, and the whole question of sprays and 

 their utilisation. 



The earlier part of the text is mainly concerned with cultural methods, whilst 



