442 



NATURE 



[April 8, 1922 



tions have been made on the living organisms, and that 

 only in certain cases has he used some intra vitam stains 

 for special purposes. It is a grievous pity, however, 

 that with such interesting material passing through his 

 hands he has not been able to employ an artist to 

 provide at least a few illustrations of the same delicacy 

 and accuracy as those to be found in the works of Jean 

 Roux. There is not a single one of the three hundred 

 figures that can be said to be a good picture of a living 

 infusorian. They are all crude and inaccurate diagrams. 



But these serious defects must not be allowed to 

 obscure the fact that there are recorded in this volume 

 many very interesting and important observations on 

 the natural history of these protozoa. The detailed 

 account, for example, of the explosion of the large 

 trichocysts of Microthorax haliodiscus, the description 

 of the conjugation and gemmation of the new Hetero- 

 trich Strombilidium gyrans, the discovery of the forma- 

 tion of small copulation buds in Cothurnia, and many 

 other records of the author's observations are really 

 valuable contributions to knowledge, and suggest at 

 any rate interesting lines of research for some one who 

 can use more modern methods of technique. 



Dr. Penard proposes to add to our lists the names of 

 several new genera and many new species ; • but it 

 seems very doubtful if these new genera and species 

 can be established until a better and more trustworthy 

 account of the nuclei and other details of structure can 

 be provided. Any one who has had experience of 

 investigations of these active minute organisms must 

 be aware of the uncertainty of observations on the 

 form and structure of the meganuclei that are made 

 when the animals are still living. Such observations 

 must be confirmed and extended by a study of properly 

 fixed and stained preparations before they can be 

 regarded as trustworthy. More particularly is this the 

 case with the micronuclei, which are usually quite 

 invisible during life and require the best technical 

 methods for their complete elucidation ; and we may 

 note, in this connection, that the author does not 

 mention either the sixteen micronuclei of Bursaria 

 truncatella or the single but remarkably conspicuous 

 micronucleus of Spirochona gemmipara. 



In a group of animals such as the Ciliata, which 

 possess so few trustworthy characters for systematic 

 work and vary so much as regards these characters 

 according to environmental conditions, the systematist 

 should not be satisfied with his description of new 

 species until every important character that can be 

 seen by the ordinary methods of research has been 

 seen and described. If microscopists pass from the 

 description of one species of Ciliata to that of another 

 before the nuclear structures of the first have been deter- 

 mined, as Dr. Penard has done, our literature, already 

 NO. 2736, VOL. 109] 



overburdened with unnecessary specific names, will soon 

 become most hopelessly perplexing and cumbersome. 



Dr. Penard's work will be useful for reference, and 

 perhaps suggestive of lines for further investigations 

 by other methods of research, but it cannot be regarded 

 as one that excites great confidence. 



(2) The new volume on the freshwater Heliozoa of 

 the British Isles published by the Ray Society gives a 

 record of genera and the species that have been found 

 by microscopists in this country who have been in- 

 terested in the group, but it does not do justice either 

 in text or plates to the important morphological 

 features or to the beauty of form that these remarkably 

 interesting protozoa possess. 



It is very disappointing that in this monograph the 

 general account of the structure and reproduction of 

 the Heliozoa is so incomplete. For example, in the 

 very slight treatment of the reproduction of Actino- 

 phrys and Actinosphaerium there is no reference to the 

 works of Schaudinn or R. Hertwig. It seems extra- 

 ordinary also that those who are responsible for the 

 publications of the Ray Society have no better methods 

 to suggest to the young microscopist for the preserva- 

 tion of these delicate organisms than 5 per cent, 

 carbolic acid, formalin, and methylated spirit, and that 

 no methods at all are given for staining preserved 

 specimens to bring out more clearly the structure of the 

 nuclei and other minute details. 



The purely systematic part of the work is more 

 satisfactory, and the microscopist will find a short but 

 clear description of all the species that have been 

 recorded in this country with references to many of 

 the more important papers in the literature of the 

 subject. Of the eighteen text-figures only two seem 

 to be original, the others being either reproductions of 

 the coarse and lifeless illustrations in Penard's mono- 

 graph or taken from other authors. Figures such as 

 these, in which the detailed structure is not clearly or 

 accurately shown, do not incite to careful and patient 

 study, although they may assist to some extent in the 

 identification of species. The illustrations in the plates 

 also, with a few exceptions, are far below the standard 

 we might reasonably expect in the publications of the 

 Ray Society. They do not represent these beautiful 

 little organisms as spherical in shape with radiating 

 pseudopodia on the whole circumference, but rather as 

 flat discs with the pseudopodia in one plane. 



Another fault which seems to be unpardonable in a 

 work of this kind is the failure to give any description or 

 descriptive lettering of the figures to assist the reader. 

 In such a figure as that on p. 44, for example, it is im- 

 • possible to determine which of the several circles in the 

 endoplasm of Pompholyxophrys is the nucleus and what 

 the other things are supposed to represent. And again. 



