April 18, 1913] 



SCIENCE 



603 



able society. Of course this involves a circle; 

 but there is no way of escaping it. 



J. E. Creighton 



SCIENTIFIC BOOKS 

 An Introduction to the Study of the Protozoa. 

 With Special Reference to the Parasitic 

 Forms. By E. A. Minchin, Ph.D., F.R.S., 

 Professor of Protozoology in the Univer- 

 sity of London. London, Edward Arnold; 

 New York, Longmans, Green & Co. Pp. 

 X + 51Y. Price $6.00 net. 

 When an " Introduction " to the study of a 

 special group covers over 500 pages of which 

 perhaps a third are in fine print, a reader 

 might infer that the main text would require 

 a lifetime to prepare and digest. Of the 

 many students of the group described in this 

 book not a few have given an entire lifetime 

 and others are now devoting all of their 

 energies to the main text. Amongst these 

 Professor Minchin is one of the most conspic- 

 uous and best informed. We think, however, 

 that he is a trifle too modest in calling this 

 splendid presentation of a difficult field an 

 " Introduction," for the great variety of sub- 

 jects discussed, the judicial attitude assumed, 

 and the wealth of references used, are more 

 characteristic of a treatise than of a primer. 

 Like the majority of general works on 

 Protozoa, this one consists of two main sec- 

 tions, one devoted to general problems, the 

 other to special groups. Such treatment in- 

 volves more or less repetition and requires 

 many cross references, but is most useful in 

 picturing the nature and extent of problems in 

 general biology, as illustrated by the Protozoa. 

 In the general section four chapters are de- 

 voted to the distinctive characters, modes of 

 life, general physiology and reproduction; five 

 chapters to the general organization and life 

 cycles, and one chapter to fertilization and 

 sexual phenomena of the Protozoa. In the 

 more special part, one chapter is given to the 

 Sarcodina, two to the Mastigophora, three to 

 the Sporozoa and one to the Infusoria, while 

 a concluding chapter deals with the general 

 phylogeny of the Protozoa and with two 

 doubtful groups, the Spirochsetida and the 



Chlamydozoa. The sub-title of the book dis- 

 arms criticism of the disproportionate treat- 

 ment of the four special groups, the Infusoria 

 receiving the least attention, but such treat- 

 ment may go a long way in overcoming the 

 too-common generalization that ciliates are the 

 Protozoa, and may help to a broader compre- 

 hension of the biological value of representa- 

 tives of the other and larger groups of unicel- 

 lular animals. 



The problem of karyokinesis, especially the 

 evolution from simple to complex mitotic 

 structures, is well treated ; a more critical dis- 

 cussion of the so-called chromosomes in 

 Protozoa and the evolution of chromosomes 

 would have been a welcome addition, since 

 there is the greatest confusion at the pres- 

 ent time over this apparently simple mat- 

 ter. The terms " chromatinic " and " achrom- 

 atinic " are used in place of chromatic and 

 achromatic, the change being adopted on the 

 ground that the latter terms have a distinctly 

 different meaning in optics. We agree that 

 the change is desirable, but there is little prob- 

 ability that it will have a wide following, since 

 these terms are firmly grounded in modern 

 biology. Another new term — " chromidio- 

 some " for the smallest unit of chromatin in- 

 side or outside of the nucleus, is most useful 

 so also is the word " endosome " for the Ger- 

 man term " Binnenkorper." 



Minchin makes a distinction between 

 Protozoa of " cellular " grade and those of 

 " bacterial " grade, but the effort seems to be 

 somewhat obscure and does not help much in 

 defining the Protozoa, having a perplexing 

 rather than a simplifying effect. The bac- 

 terial nucleus is sometimes a single karyosome 

 which might be compared with a typical nu- 

 cleus; more often there is no morphological 

 nucleus, but chromatin granules are scattered 

 about the entire organism. It is presumably 

 this type of bacterial structure that Minchin 

 refers to in Protozoa of bacterial grade, and if 

 so the Spirochaetes might well fall within 

 such a group; but these are treated separately 

 as a doubtful group. On the other hand, some 

 well-defined Protozoa, such as Dileptus gigas, 

 for example, have similar scattered chromatin 



