Ill 



the uses of the different species, and the geographical distribution 

 is given for each kind. 



The nomenclature used is that of the second edition of Britton 

 and Brown's "Illustrated Flora," but the sequence of families is 

 that adopted in the work of Clements, Rosendahl and Butters in 

 their "Minnesota Trees and Shrubs," published in 1912. This 

 is the "Besseyan System" which differs from the Engler and 

 Prantl sequence in following the gymnosperms by the orders 

 Ranales, Geraniales, Malvales, Rosales, Celastrales and so on. 

 One criticism that can be justly levelled at a purely popular 

 hand-book such as this are the names Cassiaiae, Fabatae and the 

 like, which are categories readily understandable by the trained 

 botanist, but will be unfamiliar to the greater part of the readers 

 to whom the book is addressed. 



As a workable pocket manual of trees, the book is sure to 

 have a wide range of usefulness. 



Warner, C. H., Formaldehyde as an Oxidation Product of 

 Chlorophyll Extracts, Proc. Roy. Soc. B. 87: 378-385, 1914, 

 reports a series of interesting experiments demonstrating the 

 production of an aldehyde when light acts on a film of chlorophyll 

 (prepared by allowing an alcoholic or ethereal chlorophyll 

 extract to evaporate on glass plates). The production of alde- 

 hyde goes on parallel with a bleaching of the chlorophyll, is 

 dependent on the presence of oxygen, but independent ot the 

 presence of carbon dioxide. Along with the aldehyde a volatile 

 substance, capable of liberating iodin from a potassium iodide 

 solution, is produced. 



In the same number of the Proceedings, Wager, H., The Action 

 of Light on Chlorophyll, Proc. Roy. Soc. B. 87: 386-407, describes 

 a more varied series of experiments covering essentially the same 

 ground. Warner is inclined to consider hydrogen peroxide the 

 active oxidizing agent, produced in the presence of oxygen and 

 light, which attacks the chlorophyll; Wager argues that probably 

 some other peroxide is concerned. 



This work again shows that the original experiments with 

 chlorophyll films as performed by Usher and Priestley did not 



