NOTES AND LITERATURE 



PROTOZOA 1 



That so expensive and highly specialized a text-book as this 

 of Doflein 's should run through a whole edition in less than a 

 year is a tribute to the excellence of the work and an index to 

 the scientific activity in this field of biological research. An 

 indication of the rapid progress now in the making in protozo- 

 ology may be derived from the fact that every chapter in this 

 elaborate work has been rewritten or substantially emended 

 and the number of pages and illustrations increased by fifteen 

 per cent, in this third edition, the second having been issued 

 less than two years ago. The main changes include the insertion 

 of a chapter on the origin of the Protozoa, the conception of 

 species within the group, and the phenomena of variation and 

 heredity as revealed by methods of culture and experiment, 

 especially by the study of pure lines and the results of selec- 

 tion. Doflein calls attention to the appearance of direct adapta- 

 tions in parasitic organisms in response to definite environ- 

 mental factors in the form of chemical substances such as 

 atoxyl and various compounds of arsenic and of antimony, 

 unknown in the normal environment of the protozoan organism. 

 These adaptations result in so-called resistant races and may be 

 heritable. The possibility of control, the large numbers avail- 

 able and the rapidity of multiplication of these pathogenic 

 organisms unite to open an inviting field, thus far too much 

 neglected by the investigator in experimental evolution. 



Considerable additions are made to the discussion of repro- 

 duction, especially to the maturation of the gametes, in which 

 homologies to maturation in the Metazoa are becoming increas- 

 ingly definite. The detailed discussion of the various groups 

 of protozoa is noticeably extended in the case of the Spiro- 

 chetes, the Hiemosporidia and the Sarcosporidia. 



^'Lebrbuch der Protozoenkunde. Eine Darstellung der Naturgeschichte 

 der Protozoen mit besonderer Beriicksichtigung der parasitisehen und patho- 

 genen Formen." Dritte stark vermehrte Auflage. Von Dr. F. Doflein. 

 xii + 1043 pp., mit 951 Abbildungen im Text. Jena, Gustav Fischer, 1911. 

 M. 26, gb. M. 28.50. 



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