July 21, 19 10] 



NATURE 



67 



attract flies, which are often imprisoned by th-e 

 rapid closing of the glumes. These flies seem often 

 affected by the entomophthora disease, and it is sug- 

 gested that when so suffering they are often compelled 

 by thirst to seek the juice of the lodicules. In other 

 cases, no doubt, they visit the flowers for the purpose 

 of collecting pollen. 



A very valuable appendix, occupying about loo 

 pages, is added to the volume, and gives a systematic 

 list of the various insects which have been observed 

 visiting flowers and the flowers which they usually 

 frequent. This carefully compiled list will be as in- 

 forming to the entomologist as to the botanist. The 

 index of plants described in the volume which figures 

 in the German edition has not been added in the 

 translation, but is probably held over for the final 

 volume. 



The style of the English rendering is fluent, and 

 generally free from the flaws that mark some trans- 

 lations, though the volume opens with a serious 

 blunder in describing the flowers of Lobelia as actino- 

 morphous. Halftig-symmetrisch is, of course, bi- 

 laterally symmetrical or zygomorphic, as is, indeed, 

 indicated by the concluding portion of the sentence 

 which describes the bifid upper and the trifid lower 

 lip. It is unfortunate that the translator has retained 

 the use of the word oecology as a synonym for 

 biology, in dealing with observations on flower pol- 

 lination. Though formerly used in that sense, oecologv 

 has of late years been so definitely and much more 

 correctly applied to the study of plant-life in relation 

 to environment that it seems out of place when used 

 for floral biology. 



-Apart from such minor defects, the translation will 

 be welcomed as rendering Knuth's monumental work 

 accessible to a wider circle of readers and students of 

 plant biology. 



PRACTICAL WORK FOR ELECTRICAL 

 LABORATORIES. 

 Lcitfaden ziim elektrolfchnischen Praktikiim. By Dr. 



G. Rrion. Pp. xiv + 404. (Leipzig and Berli--. : 



B. G. Teubner, 1910.) Price 11 marks. 

 'T'HE laboratory has always been regarded as a 

 -»- necessary complement to the class-room so far 

 as physics and chemistry are concerned, but lor 

 engineering subjects it is a comparatively modern 

 institution. There are still engineers amongst us who 

 have had to go through their university training with- 

 out enjoying the use of a laboratory, but within the 

 last generation all technical universities and colleges 

 have recognised the immense importance of laboratory 

 work, and have fitted up hydraulic, heat, mechanical, 

 and electrical laboratories on a more or less extensive 

 scale. Teachers, as well as engineers in practice, are 

 agreed on the necessity of supplementing the theo- 

 retical work of the class-room by e.xperiment, and 

 there is keen competition between the different institu- 

 tions as regards the best equipment, each trving to 

 profit by the experience of the others, and to adapt 

 the plant to the special industrial requirements of its 

 district. 



The best equipped laboratory would, however, be 

 of little value without good organisation in its use 

 NO. 2125, VOL. 84] 



and scientific instruction in the way of carrying out 

 experiments. The book under review is an attempt, 

 and, let us hasten to say, a very successful attempt, 

 to supply such instruction. Of all Continental tech- 

 nical high schools, Dresden has at the present moment 

 the best equipped electrical engineering laboratory, 

 and since its head, Prof. Goerges, is not only an 

 accomplished teacher, but also an engineer of high 

 reputation, we may expect that a book, treating of 

 laboratory work as carried on under him, will prove 

 a most useful publication. The author is lecturer at 

 Dresden, and in the preface says that the methods 

 described have been worked out from time to time 

 bv various members of the staff. This does not mean 

 that the methods described, or even a majority of 

 them, are new, but simply that all the methods 

 described have actually been used in that laboratory, 

 and that in this w-ay the educational value of each 

 has been put to the test. 



If an author describes the equipment of and work 

 done in the laboratory in which he works himself, 

 there is danger that he will produce a somewhat one- 

 sided account, but from such a reproach Mr. Brion 

 is entirely free. All the author has to say on testing 

 applies to any well-equipped laboratory, and there is 

 a remarkable absence of references to special appara- 

 tus. He evidently does not hold with the custom 

 of giving the student cut-and-dried instructions, such 

 as "take Messrs. So and So's testing set, connect in 

 such a manner, then turn the handle and read off the 

 result." Wherever possible he not only lets the 

 student build up his apparatus, but he gives him also 

 a short theory of the test. The object of the student's 

 work in the laboratory is primarily to verify by experi- 

 ment certain physical relations of which he has heard 

 the theory in the class-room. Since, however, the 

 simple and fundamental physical relations are in prac- 

 tical machinery often overshadowed by secondary dis- 

 turbing causes, it is important that these should be 

 pointed out to the student, and that he should thus 

 be trained to scrutinise his results so as to separate 

 that which is important from that which is merely 

 accidental or disturbing. In this direction, Mr. Brion 

 has given us good advice in suflicient detail. To 

 give such advice it is, however, necessary to intro- 

 duce a certain amount of theoretical matter on a 

 mathematical basis. 



.-\ casual glance through the pages of this book 

 gives one more the impression of a text-book than 

 of a laboratory manual, but on closer inspection one 

 finds that only as much theory is introduced as is 

 necessary for intelligent working. Among the good 

 features of the book are the diagrammatic representa- 

 tions of circuits, machines, and apparatus. With a 

 correct appreciation of the probability that the 

 students who work now in the laboratory will in a 

 year or two be working in practice, Mr. Brion has 

 adopted in his diagrams the symbolic representatioi* 

 recommended by the Verband Deutscher Elektrotcch- 

 niker. He also uses, thick lines to represent wires 

 which carry main currents and thin lines for wires 

 carrying shunt currents or for voltmeter wires. This 

 is apparently a small matter, but anyone who has to 

 trace out the circuits in some complicated electrical 



