38 THE AMERICAN BOTANIST 



author has been greatly aided by his studies of fossil species 

 which, owing - to improvements in technique, are now almost 

 as easily studied as sections of fresh material. Though 

 botanists long ago abandoned the idea that the dicotyledons 

 originated from the monocotyledons and trees from herbaceous 

 forms, it may be worth mentioning in passing that the author 

 finds no evidence in support of the old belief. As a matter of 

 fact, the monocotyledons are now supposed to have arisen from 

 the dicotyledons and herbs from trees. In some monocotyle- 

 dons a second rudimentary cotyledon is frequently found. A 

 great group of plants, the Pteropsida, which has existed from 

 early geological times with possibly all its forms tree-like in 

 the beginning, is assumed to have given rise to three great 

 divisions, namely : the fern-like plants, the Gymnosperms of 

 conifers, and the Angiosperms or true flowering plants. On 

 anatomical and other grounds the author regards the genus 

 Casurina as one of the most primitive of dicotyledons and 

 closely related to the Betulaceae, Fagaceae and Ericaceae. This 

 latter family ( the heaths) has always held a much more advanced 

 position in systems of classification. The book is of special 

 interest for the large number of photo-micrographs used as 

 illustrations. Such examples carry conviction when a mere 

 drawing would not. There are 475 pages and 306 illustrations 

 in the book, which is octave in size. It is published by the 

 University of Chicago Press, at .$4.00 net. 



