NOTES AND COMMENT 



An important gap in our knowledge of the developmental mor- 

 phology of the Pteridophytes has been filled by Prof. A. Anstruther 

 Lawson, of the University of Sydney, in his investigation of the pro- 

 thallia of Psilotum and Tmesipteris (Trans. Royal Soc. Edinb., vols. 

 51, 52). This work gives us the first knowledge of the sexual genera- 

 tion of these relict genera, if we except the work of Lang, based on 

 material which Professor Lawson now regards as having pertained to 

 some plant other than Psilotum. The members of both genera are 

 commonly epiphytic on arborescent ferns, and the brown rhizome-like 

 prothallia were found on the rough fern trunks in several localities. 

 The development is very similar in the two genera, and the vegetative 

 characters and development are alike in presenting important differ- 

 ences from the prothallus of Lycopodium, as well as from that of Equi- 

 setum. The relationship of these plants to Lycopodium is therefore not 

 so close as has been presumed, and strength is thereby given to the 

 view already advanced by several workers that they have their closest 

 affinities with the extinct Sphenophyllales. 



The second part of Prof. W. F. Ganong's Textbook of Botany for 

 Colleges has recently appeared (Macmillan, 1917). It is chiefly de- 

 voted to a description of the morphology and relationships of the great 

 groups of cryptogamic plants and the orders of phanerogamic plants. 

 The treatment is brief and general, but is accurate and down to date, 

 and the illustrations are both numerous and excellent. A final chapter 

 on the ecological classification of plants is well done, but it demon- 

 strates how difficult it is to marshal the generalizations of ecology into 

 a well-ordered presentation such as that given the facts of morphology. 

 The appealing style in which the book is written should give it a field 

 of utility outside the classroom, among that small and rapidly vanish- 

 ing body of adults who read to improve their minds. 



Around the Year in the Garden is a very practical and comprehen- 

 sive book by which Mr. Frederick Frye Rockwell makes it possible for 

 the man who is without a head gardener to carry out all of the opera- 



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