VI 



Supplement to "Nature" February 5, 1903. 



observations only. One feels that the theorv of errors 

 has not been grasped with a complete mastery. After 

 glancing at such uncomfortable-looking formulae as 

 BC = rftan (BAC + 0-000069 d) and wondering whether 

 there is any advantage in such forms of expression as 

 cos. of co-dec, in place of the more familiar Sin. dec, 

 we turn to the section on longitude determination to 

 learn how the method is practised by civil engineers and 

 surveyors. And in this chapter one learns some strange 

 things. It does not appear to be at all necessary to take 

 into account the parallax of the moon in the method by 

 lunar distances, and the problem of "clearing the 

 distance," a problem fraught with much pain and anxiety 

 to many, does not seem to trouble engineers and sur- 

 veyors. Similarly, the longitude by lunar occultations is 

 treated with equal lightness and brevity. We are told 

 that the Greenwich mean times of the occultations of 

 fixed stars by the moon are given in the Nautical 

 Almanac for both immersion and emersion, and that by 

 applying the approximate longitude in time, the approxi- 

 mate local mean time of the occultation may be found, 

 and the observer will know approximately when to begin 

 to observe. We recommend the two or three pages of 

 explanation of the section "Elements of Occultation" 

 given at the end of the Nautical Almanac to the author's 

 attention. 



These remarks are not made in any unkind spirit, but, 

 if possible, to warn the student to what extent he may 

 trust his author. We can readily believe that with his 

 chain and his theodolite, the writer of the book has done, 

 and will continue to do, good work, and if he had been 

 content to describe accurately what he knew thoroughly, 

 he would have given us a valuable practical treatise. 

 But he has ventured on subjects of which his experience 

 has not qualified him to treat, and in these directions we 

 can neither follow him with satisfaction nor unreservedly 

 recommend his book to the careful study of the large 

 class of students who might have profited by it. 



W. E. P. 



PRO TOZOAN NA TURAL HIS TOR J '. 



Faune Infusorienne ties Eaux stagnantes dcs Environs 

 de Geneve. Par Dr. Jean Roux, Assistant au Labora- 

 toire de Zoologie de l'Universite de Geneve. Pp. 14S ; 

 8 plates. (Geneve: H. Kundig, 1901.) 



Faune Rhizopodique d/t Bassin du Le'man. Par Dr. 

 Eugene P^naid. Pp. 714. (Geneve: H. Kundig, 

 1902.) 



THE systematic study of the natural history of the 

 Protozoa in past years has, in general, lagged far 

 behind that of the higher groups of animals. In large 

 part, no doubt, this has been due to technical difficulties 

 of collection and examination, but it has resulted also 

 from a delay in recognition of the fact that the same 

 problems of species and of their geographical distiibu- 

 tion which have stimulated and directed the detailed 

 study of Metazoan natural history for so many years 

 have equivalent applicability and interest among the 

 Protozoa. The brilliant labours of Ehrenberg, however, 

 NO. 173^, VOL. 6/] 



who concerned himself largely with the local distribution 

 of Protozoan forms, and the later work of Biitschli, have 

 been increasingly fruitful. The conception by Biitschli 

 of the "cosmopolitanism" of the Protozoa has been sup- 

 ported by the results of numerous workers in various 

 countries and continents, and found its fullest sanction in 

 the studies of Schewiakoff during his voyage round the 

 world. Schewiakoff, indeed, by showing in how large a 

 proportion the Protozoan species already well known in 

 Europe were spread through other continents, opened 

 the most attractive field for the study of the problem of 

 species among the unicellular animals. 



The two valuable monographs we now owe to Drs. 

 Roux and Penard will rank high among the later con- 

 tributions to the Protozoan natural history. Concerned as 

 they are with the exact description of a purely local 

 fauna, they may be considered to be in a sense comple- 

 mentary to the extensive researches of Schewiakoff — 

 they have a value which is intensive, rather. With the 

 general idea of Protozoan ubiquity and specific " cosmo- 

 politanism" well grounded, we may hope that by the 

 sufficient accumulation of exact local studies, and per- 

 haps in no other way, we may eventually see unravelled 

 the intricate relationships of nutritive conditions and of 

 the environment in general, not only to secondary body 

 characters, but to the processes of fission and its secon- 

 dary developments, which determine to so large a degree 

 the life-histories of the Protozoa. Not the morphologist 

 alone, but the physiologist too, will welcome the advances 

 of our knowledge in this direction, for the latter must 

 hope to gain a widely increased outlook upon the 

 significance and origin of many cellular processes by 

 the determination of the phylogenetic relationships 

 among groups of Protozoa. 



Dr. Jean Roux has collected, identified and described 

 in detail the species of Infusoria occurring in the stagnant 

 waters, in pools, marshes and basins in the neighbour- 

 hood of Geneva. His work gives fresh verification, it 

 any were required, to the very generalised distribution of 

 Protozoa throughout the world, for he has already found 

 in his own distiict three-fifths of all the forms of non- 

 marine Infusoria which have been described for other 

 countries. His arrangement of the species follows 

 Butschli's classification, except in the order Holotricha, 

 in which the divisions of Schewiakoff are adopted. 

 Very complete systematic descriptions are given of every 

 form, the arrangement and shape of its organs, its 

 characteristic movements, and, in most cases, its normal 

 habitat and mode of nutrition. 



The text is illustrated by well executed coloured plates, 

 which give figures, drawn by the author, of about 170 

 species. Some interesting points are raised by Dr. Roux 

 in connection with the seasonal changes of population 

 among the Infusoria. Statistical inquiry has shown that 

 the population of a given species exhibits maxima and 

 minima of seasonal incidence. In general, a maximal 

 population is found both in spring and autumn, a fact 

 which has not yet received adequate explanation. These 

 two maxima may be real ; they may be due to increased 

 reproductive activity both in preparation for, and in con- 



