NATURE 



433 



THURSDAY, MARCH 13, 1902. 



A NEW MANUAL OF THE PROTOZOA. 

 The Protozoa. By Gary N. Calkins. Columbia Univer- 

 sity Biological Series, VI. Pp. xvi 4- 347 ; 153 text- 

 figures. (New York : The Macmillan Co. London : 

 Macmillan and Co., Ltd., igoi.) Price \2s. 6d. net. 



BIOLOGISTS have understood for a long time past 

 the importance of the study of the Protozoa as 

 an indispensable aid to the solution of some of the 

 most fundamental problems of biology. Of recent years, 

 however, a lively interest in this class of organisms has 

 been awakened in many others besides those whose field 

 of investigation includes the Protozoa amongst its recog- 

 nised subjects. Medical researchers, for instance, require 

 now to know more about the simplest forms of animal 

 life than they were taught, as students, in their elementary 

 courses of biology, and even the general public has had 

 its attention directed to " microbes " by the recent dis- 

 coveries concerning the etiology of malaria and the 

 wonderful life-history of its minute parasite. The time 

 is opportune, therefore, for the publication of a general 

 account of the Protozoa, and the latest addition to the 

 well-known Columbia Series is a handy volume which 

 will be welcomed by many classes of readers. The author 

 has not aimed at putting forward an exhaustive, severely 

 scientific treatise upon the group in question. His work 

 may be described rather as a simple and intelligible 

 introduction to the study of the Protozoa and of the 

 many fascinating biological problems connected with, or 

 illustrated by, this subdi\ ision of the animal kingdom, in 

 such a way as to awaken the interest of the beginner, no 

 less than to strengthen the hands of the expert. The 

 book is written m plain language, with avoidance of un- 

 necessary technicalities, and is profusely illustrated by a 

 great number of very excellent figures, in the preparation 

 of which the author acknowledges the assistance of his 

 wife, whose skilful draughtsmanship cannot be praised 

 too highly. 



The author treats his subject, as stated in the preface, 

 from three points of view : (i) the historical, which occu- 

 pies the first chapter ; (2) the comparative, on which five 

 chapters are spent ; and (3) the general, to which the last 

 three chapters are devoted. The historical and mtro- 

 ductory chapter gives an extremely interesting account 

 of the progress of our knowledge of the Protozoa, and 

 traces the gradual elimination of the many erroneous 

 notions prevalent even not so very long ago. 



The comparative account is a useful review of the 

 whole group and of the four principal subdivisions, 

 the Sarcodina, Mastigophora, Sporozoa and Infusoria. 

 The author is extremely up to date in his facts, and 

 makes use of the most recent observations and dis- 

 coveries. In the chapter on Sporozoa we find Siedlecki's 

 recent account of the conjugation of the sporoblasts in 

 Monocyslis {Lankes/eria) ascidiae taken as typical for the 

 class (p. 151) and made the basis of six good diagram- 

 matic figures representing the "scheme of sporulation in 

 gregarinida" (Fig. 84, p. 152). The book must have 

 been out of the author's hands before the publication of 

 NO. 1689, VOL. 65] 



Cuenot's recent memoir describing a perfectly similar 

 type of conjugation in the common Monocystis of the 

 earthworm, but it is nevertheless unfortunate that the 

 now exploded account put forward by Wolters for this 

 type should be quoted so frequently (pp. 1 57, 235 and 

 elsewhere), especially as Wolters' statements are directly 

 at variance with the "scheme of sporulation" to which 

 reference has been made. 



The three general chapters deal with sexual phenomena 

 in the Protozoa, with the special morphology of the 

 Protozoan nucleus, and with some problems in the 

 physiology of the Protozoa respectively. The sexual 

 phenomena are divided into four categories — union of 

 similar adult individuals, of similar but different-sized 

 individuals, of swarm spores or reduced individuals, and, 

 lastly, of "eggs and spermatozoa," i.e. of highly differ- 

 entiated gametes. A great deal of very interesting 

 matter is brought forward under each heading, but the 

 facts relating to the Coccidia, which form the bulk of 

 the fourth subdivision, are set down in a very inaccurate 

 manner, and require revision. It is not true, for instance, 

 to say that " so far as the nucleus (of the macro gamete) is 

 concerned, ... no maturation process has been recorded," 

 unless the term maturation be used in a very restricted 

 sense. In Adelea ova/a the entrance of a male element 

 is not effected through a special opening or micropyle, as 

 stated; but perhaps Coccidium prop7-ium is meant, where 

 this does occur. Again, it is incorrect to say that in 

 Adelea ovata the microgamete divides twice while in 

 contact with the macrogamete, and that three of the 

 resulting nuclei are eliminated. It is the microgameto- 

 cyte which divides in this way to furnish four micro- 

 gametes, one of which fertilises the "egg." In a book 

 which bears evidence of so much careful and well-con- 

 sidered work, it is strange to find so many misstatements 

 so close together, but the whole paragraph (pp. 229-232), 

 from which is taken the above statement concerning the 

 microgamete, is confused and contradictory, since, begin- 

 ning by referring to Adelea by name, and without 

 introducing the name of any other species, it goes on to 

 make statements which evidently refer to Coccidium, and 

 then to institute comparisons between the facts stated and 

 the processes occurring in other Coccidia, including 

 Adelea itself 



In the chapter dealing with the nucleus, an attempt is 

 made to trace the steps in the elaboration of the structure 

 of Protozoan nuclei and of the mechanism of nuclear 

 division. Four stages are recognised in the evolution of 

 nuclear structure: (i) compact spheres of chromatin, 

 multiple division of which is the prelude to the reproduc- 

 tion of the cell ; (2) nuclei with membranes, enclosing 

 each one or more chromatin masses or " karyosomes,'' 

 which break up to form granules, and the granules unite 

 secondarily in lines forming primitive chromosomes ; 

 (3) nuclei without karyosomes, with granules distributed 

 widely over the nuclear framework ; (4) nuclei with 

 granules as in (3), or aggregated into " net knots " which 

 break up into granules at the period of nuclear division, 

 the granules then coming together in lines which seg- 

 ment into chromosomes of definite number and size. The 

 fourth and highest of these stages is that found in Meta- 

 zoa and Metaphyta. The author comes to the conclusion 



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