September 29, 19 10] 



NATURE 



593 



" W " is a Nicols prism will be apt to confuse the 

 student. The resistance pyrometer is said to give the 

 correct temperature to a tenth of a degree at 1000° 

 C but owing to the coating required to protect 

 th;' platinum wire for most work, nothing like 

 this accuracy will be obtained in practice. In speak- 

 ing of the useful Fery spiral pyrometer, it is indicated 

 that one of its objections is that it will only give 

 " black body " temperatures, but surely this limitation 

 applies to the other radiation pyrometers also. 



The account of the manufacture of Shefifield steel- 

 melting crucibles is not correct, nor is the statement 

 (p. 346) that the crucible is "put to dry, after which 

 it is used without firing," as these crucibles are sub- 

 jected to a very careful firing, or annealing, on a 

 very ingeniously designed annealing grate. Also, 

 amongst the addition of non-plastic material added to 

 enable the crucible to be made without cracking, are 

 mentioned burnt clay, silica, and graphite; but in 

 Sheffield work the material used is the best ground 

 coke-dust, which not only has this effect, but by 

 forming a solid skeleton to the material of the crucible 

 at temperatures at which the fireclay material is quite 

 soft, enables the crucible to stand the necessarily 

 rough usage to which it is subjected during the 

 making of crucible steel, without losing its shape. 

 If from any little accident in the annealing of the 

 crucible air has been allowed to impinge on any part 

 of it so as to burn out the coke-dust, the crucible 

 loses its shape at these portions, and is exceedingly 

 difficult to manipulate. 



The whole subject-matter of the book covers a very 

 wide field, and these critical observations are not in- 

 tended to indicate that the work will not be a useful 

 one for students, but are only intended to set them 

 on their guard in cases where it will be necessary for 

 them to know the exact state of practical work, or to 

 compare with other authorities where their own ex- 

 perience seems to differ from the statements made in 

 the book. A. McWilliam. 



yiEDlCXh PARASITOLOGY. 

 A Handbook of Practical Parasitology. By Prof. Max 

 Braun and Dr. M. Liihe. Translated by Linda 

 Forster. Pp. viii + 208. (London: J. Bale, Sons 

 and Danielsson, Ltd., 1910.) Price los. 6d. net. 



THIS is a handy and very useful work by two ex- 

 tremely competent authorities, and well worth 

 translating into English for the benefit of medical 

 men and others to whom the German language may 

 present difficulties. The book is divided into three 

 parts — (i.) Protozoa, (ii.) Helminthes, and (iii.) .Arthro- 

 poda. Each of these sections begins with an intro- 

 ductory portion, in which, after a general account of 

 the group, very full directions are given for its prac- 

 tical study, with an excellent summary of the most 

 important and useful methods of technique. The 

 group is then dealt with systematically, those forms 

 most important for the purposes of the book being 

 described in their place in the classification, and for 

 each main subdivision a common and easily obtained 

 tvpe is described in detail with directions for procur- 

 NO. 2135, VOL. 84] 



ing and studying it. The information given is in 

 general accurate and up-to-date — the date, that is to 

 say, of the German edition — and the figures are clear 

 and well executed. 



In the Protozoa the step is taken of abolishing the 

 class Sporozoa and elevating its two principal sub- 

 divisions, Neosporidia and Telosporidia, to the rank 

 of independent classes. The Neosporidia are placed 

 immediately after the Rhizopoda, while the Telo- 

 sporidia follow the Flagellata, but with subtraction of 

 the Heemosporidia, which are classified with the 

 Trypanosomidse amongst the Flagellata as the third 

 order, Binucleata, of that class. In their treatment of 

 these organisms the authors take up an advanced neo- 

 Schaudinnian standpoint with regard to certain highly 

 controversial questions. 



The term Helminthes has no zoological significance, 

 but is used in a sense convenient for medical require- 

 ments to comprise the Trematodes, Cestodes, Nema- 

 todes, and Acanthocephala ; not, however, the leeches. 

 In the section Arthropoda, which is a brief one, an 

 account is given of the mites, Linguatulids, lice, fleas, 

 and parasitic Diptera. The .Arthropods which trans- 

 mit parasites, such as ticks and "stinging-flies" (sic), 

 are .dealt with under the Protozoa. 



The translation is, in general, clear, but some 

 curious results arise from the translator's desire to 

 anglicise scientific terms. It appears to be a rule with 

 her to convert the termination "-idium," plural 

 "-idia," into "-ide," plural "-ides," and the conse- 

 quences are in many cases very puzzling. "Coccide," 

 for instance, suggests a cochineal insect, but means 

 in this book a coccidian parasite. No zoologist would 

 ever guess the meaning of " Myxides," used to denote 

 individuals of the common parasite of the bladder or 

 the pike, Myxidium lieberkiihni. Most zoologists, and 

 manv people' who are not zoologists, are familiar with 

 chromidia, disguised here as " chromides." In these 

 and many other cases the meaning of the term used 

 can only be inferred from the context or deduced from 

 analog)-. It is also very misleading to use the term 

 "carnivori" to denote birds of prey (p. 60); "small- 

 pox" on p. 32 should be carp-pox; and Trypanosoma, 

 in the description of Fig. 14, should be Trypano- 

 plasma. It is to be regretted that the eminent zoolo- 

 gists and others, to whom the translator expresses her 

 indebtedness for assistance, did not correct these 



vagaries. 



E. A. M. 



POPULAR ASTRONOMY. 

 (i) Astronomy, a Handy Manual for Students and 



Others. By Prof. F. W. Dyson, F.R.S. Pp. vii + 



247. (London: J. M. Dent and Sons, Ltd., 1910.) 



Price 2s. 6d. net. 

 (2) Chats about Astronomy. By H. P. HoUis. Pp. 



vi + 226. (London: T. Werner Laurie, n.d.) Price 



3$. 6d. net. 



MANY signs point to the fact that the popular 

 interest in astronomy grows from day to day. 

 Perhaps in revolt against the merely utilitarian the 

 world will not willingly let die the least obviously 

 practical of the sciences. The production of books. 



