June 5, 1903.] 



SCIENCE. 



yo5 



group' and remark that ' abelian group' is 

 used in an entirely different sense in linear 

 group theory. In § 38, on abstract groups, 

 it is stated that ' these generating elements 

 define the group completely,' whereas the gen- 

 erating elements with a complete set of gen- 

 erational relations are necessary for the def- 

 inition of the group; also as alternative for 

 ' equations ' should be given ' generational 

 relations.' In § 63 add ' itself and.' In § 73, 

 3 the correspondence should be defined. For 

 (m — 1) read (m, 1). In § Y4, for (m — n) 

 read (m, n). In §85, the identity group is 

 not, as usual, included in the composition 

 series. In § 239 is quoted incorrectly the review- 

 er's generalization of Hermite's theorem on 

 the analytic representation of a substitution 

 of degree p" . The two congruences modulo p" 

 should be equations in the Galois field of order 

 i " . Since the variable z is indeterminate in 

 the field, the only reduction consists in apply- 

 ing the algebraic equation eP'' = z and redu- 

 cing the coefficients modulo p. In formula 9 

 of page 84, p*" — 1 should read p^" — 1. 



For so elaborate a piece of work, executed 

 with such thoroughness and success, both the 

 specialist and the beginner in group theory 

 must feel most grateful. In pointing out 

 various errors in the literature, a valuable 

 service has been rendered to the student. 

 L. E. Dickson. 



Pathologische Pflanzenanatomie. E. KiJSTER. 



Gustav Fischer, Jena. 1903. Svo. Pp. 



iv + 312; 121 figs. 



Dr. Kiister's investigations upon gall-for- 

 mations and structures of similar character 

 in the plant has led him to a discussion of the 

 entire subject of pathological anatomy of 

 plants. The text-book resulting from this 

 treatment of the subject takes into considera- 

 tion the major structures that might be con- 

 sidered as histological or organographical de- 

 partures from the normal, but does not include 

 degenerations, or the phenomena of decay due 

 to fungi or other causes. 



The various abnormalities are classified ac- 

 cording to the cytologieal and topographical 

 features presented by their development, and 

 are embraced under the following general 



heads: Eestitution, Hypoplasie, lletaplasie, 

 Hypertrophie and Hyperplasie. Restitution 

 is the term applied to all processes set in ac- 

 tivity by the loss of a tissue or an organ, and 

 may include the replacement of the lost mem- 

 bers by the development of new ones on ad- 

 jacent parts of the body, or on the injured 

 surface; the substitution of an organ of a 

 different character arising on the injured sur- 

 face, or the substitution of an organ of a dif- 

 ferent character on adjacent portions of the 

 plant. Hypoplasie includes all processes re- 

 sulting from disturbances of any kind in 

 which the number, size or differentiation of 

 the cells does not attain the normal. Meta- 

 plasia is taken to include all development of 

 the protoplasts by which their structure, com- 

 position, form or character of the membrane 

 is different from the normal, and includes all 

 progressive changes of the cell not connected 

 with growth and division. Hypertrophy is 

 used in its accepted sense to designate the 

 production of abnormally large cells which 

 may be aggregated in such manner as to re- 

 sult in abnormally large organs. Such en- 

 largements may ensue in meristematic or 

 permanent tissues. Hyperplasie is used to 

 designate the abnormal increase in the 

 volume of a tissiie resulting from an unusual 

 multiplication of the cells. Such increase in 

 the number of cells may consist in the forma- 

 tion of a surplus number of the ordinary 

 tissues, or by the formation of cells of a dif- 

 ferent character, such as in galls or calluses. 



The two last-named divisions of the subject 

 are of the greatest importance from the stand- 

 point of the practical pathologist, and are 

 given an adequate treatment in the present 

 volume. These sections of the book owe 

 much of their value to the original matter ad- 

 duced by the author from his own investiga- 

 tion. The concluding section of the book 

 consists in a general consideration of the 

 etiology and morphology and pathological 

 structures, and sets forth some of the more 

 important problems of general pathology. 



Dr. Kiister's book is invaluable to the stu- 

 dent of plant pathology, and has much more 

 to commend it than any of the few reading 

 books on the subject which have been written 



