3oS BOTANICAL GAZETTE [October 



the family are given concisely, as well as the more interesting features of the 

 history, distribution, and uses of the more important economic representatives. 



The book is written in attractive style, and the material is well selected, 

 and is a commendable effort to differentiate secondary-school botany from 

 university botany. The numerous half-tones are of unusually good quality. 



Martin^ has attempted the same task, except that his book is more 

 specifically directed to the botanical needs of the student of agriculture. The 

 first part deals with flowers, seeds, cells, roots, stems, buds, leaves, etc. The 

 application to agriculture consists chiefly in the fact that economic plants are 

 used as illustrative material. For example, oats, corn, wheat, pineapple, 

 tomato, etc., are made to show the usual fundamental facts of morphology. 

 The second part presents an outhne of the plant kingdom, from Thallophytes 

 to Angiosperms, along with chapters on ecology, evolution, heredity, and 

 plant breeding. 



The presentation throughout is botanical rather than agricultural, a 

 foundation for agricultural study rather than a study of agriculture. The line 

 drawings are not as well done or as accurate as they should be, and the illus- 

 trations in general are in contrast with the excellent presswork and the easy 

 and pleasing style of presentation. — F. L. Stevens. 



NOTES FOR STUDENTS 



Physiology of dormancy. — Recent work by Crocker and Harrington^- 

 materially increases our knowledge of the physiology of dormancy and germi- 

 nation of seeds, and throws much light on the problems of vitality and respira- 

 tion. Differences in the optimum temperature requirements for germination 

 of Johnson grass and Sudan grass led to a study of their physiological differences, 

 and a comparison of their behavior with seeds of widely separated groups of 

 plants. The discussion therefore is a general contribution* of much significance 

 to seed physiology. The study centers in the relation of catalase content to 

 dormancy and vitality. Some improvements in methods of measuring catalase 

 activity are suggested, chief of which is neutralization of the hydrogen peroxide 

 used, as it is found to be injuriously acid if unneutralized. Degree of pulveri- 

 zation must be considered, as seeds vary somewhat as to optimum degree of 

 fineness. Bolting cloth of 70-100 mesh gave the best results in the seeds used. 

 Material must also be freshly ground, as degeneration of catalase is rapid 

 after destruction of morphological integrity. 



Catalase activity is found to be 28 or 29 times as great in the embryo of 

 Stoner wheat as in the endosperm. Sudan grass and a hybrid between Tunis 

 grass and sorghum gave similar results. Bracts surrounding the caryopses, 



2 Martin, J. N., Botany for agricultural 'students. 8vo. pp. xv-fsSs. figs. 

 488. New York: John Wilej^ & Sons. 1919. 



3 Crocker, Wm., and Harrington, G. T., Catalase and oxidase content of 

 seeds in relation to their dormancy, age, vitality, and respiration. Jour Agric. 

 Research 15:137-174. 1918. 



