BOOK REVIEWS. 



671 



additions and modifications to the account of the Sphenophyllales. The 

 bearing of recent work (on Psilotum and T7nesiptens) on the supposed 

 connexion between Sphenophyllaceae and Psilotaceae is fully dis- 

 cussed. Incidentally, the "genus " (?) Psilophyton is discussed, and 

 the author suggests that probably the various forms now grouped under 

 this name will be found later to belong to various genera, and even to 

 different phyla. 



"The greater part of vol. ii. is devoted to Lycopodiales and Filicales. 

 The Pteridosperms are reached on p. 485, but will receive more attem 

 tion in vol. iii. An interesting feature of the book is that a brief survey 

 is given of the existing plants of any group before the fossil plants of 

 the group are described. This will be specially useful to students of 

 geology, while students of botany, who should he familiar with the 

 matter of these surveys, will welcome them none the less, since the 

 arrangement makes comparison easy. 



We are glad to see that, in his discussion of morphological 

 problems, the author protests strongly against the formal attitude of 

 mind which causes so many writers to try to lit every plant organ into 

 an artificial scheme of plant members. It is by no means necessary 

 that a sporangiophore should be labelled " shoot," " leaf," or '' sterile 

 frond," or that an " underground organ " of a fossil plant should be 

 described in terms ("root," "rhizome," &c.) which have been the 

 result of comparative study of receiit plants only. Professor . Seward 

 says (and we cordially agree) that " discussions of this kind (on the 

 nature of the sporangiophore) tend to assume an exaggerated import- 

 ance, and frequently carry with them the implication that every appen- 

 dage of the nature of a sporangiophore can be labelled either ' shoot ' 

 or ' leaf.' We treat the question from an academic standpoint, and run 

 a risk of ignoring the fact that the conception of stem and leaf is based 

 on morphological characteristics, which have been evolved as the result 

 of gradual differentiation of parts of one originally homogeneous whole. " 



The illustrations are very useful and clear. In some cases the 

 practice of showing only the small part of the object in a sketch makes 

 the drawings less artistic than they might be, but in these cases the 

 illustrations are what they profess to be — namely, illustrative sketches 

 in which artistic finish is subordinate to morphological accuracy and 

 perfect clearness. There are some good photomicrographs and a full 

 hst of authorities. ' ■ 



"Morphology of Gymnosperms. " By J. M. Coulter, Ph.D., and 

 C. J. Chamberlain, Ph.D. 8vo., 458 pp. (University Press, Cam- 

 bridge, 1910.) 16s. net. - 



This is a valuable work, and must be studied by all interested in 

 the minute structure of gymnosperms. It deals very fully with the 

 latest researches, not only of the authors, but others ; and covers the 

 ground, as far as is known at present, of fossil as well as living 

 members of the group. It is beautifully illustrated, and contains . 

 an ample bibliography and index. 



