ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 605 



value of a bacteriological examination of drinking-water, concludes that it 

 is not safe to rely on it as a practical test both for the reasons given above, 

 and also because the presence of micro-organisms is no test of impurity, 

 since it is the opinion of some observers that many of these microbes 

 are normal constituents of drinking-water. Much, too, is to be said 

 against laying too much stress on the pathogenic character of the 

 organisms when they are found to liquefy gelatin. 



Apparatus for the Bacteriological Examination of Water.* — In 

 order to distribute with regularity all the germs present in a specimen 

 of water on the gelatin plate, and at the same time to be able to 

 distinguish these from aerial impurities, M. Arloing has devised a 

 complicated "analyser." A rectangular copper box, 250 cm. long, 

 85 cm. broad, and 36 cm. high, is so far closed on the short sides 

 by two glass lids, movable on hinges, that there remains between them 

 a space 7 era. broad. The interspace can be closed by means of a 

 piece of metal with a hole in the middle. To one of the small sides is 

 fixed a support, on which a pipette is fixed, so that it can hang vertically 

 down through the interspace passing through the aperture in the metal 

 plate. The support, and with it the pipette, is able to be moved in the 

 direction of the cleft by means of a screw arrangement. On the bottom 

 of the box is a strip of brass for the reception of a glass plate, and 

 which also by means of a screw is movable in the long axis of the box. 

 The glass plates intended for the gelatin have raised edges, are 

 12 cm. long, 5 cm. broad, and divided into 6U squares of 1 sq. cm. each. 



When water is to be tested, a gelatin plate is introduced, and the 

 pipette filled with water to be examined. The latter is then allowed to 

 fall drop-wise on the gelatin plate, so that every square space receives 

 one drop. The plate is then removed to an incubator. 



The advantages claimed for this apparatus are that the water is 

 distributed regularly all over the plate, and that germs from the air are 

 excluded. 



Chemical and Bacteriological Examination of Water.f — Drs. F. 

 Tiemann and A. Gartner have just issued the third edition of Kubel- 

 Tiemann's ' Introduction to the Examination of Water.' The present 

 edition, which has been enlarged and thoroughly revised, is illustrated 

 with many wood engravings, and ten chromolithographic plates. The 

 work is divided into three parts. The first of these, for which Tiemann 

 is responsible, is devoted to chemical examination ; the second, which 

 is the work of Gartner, deals with the microscopical and bacteriological 

 examination of water ; while the third part, which is the joint work of 

 both authors, sums up the results of the chemical and bacteriological 

 experiences. 



The book seems to have had considerable care bestowed upon it, and 

 is rich in details which are useful to various classes of students interested 

 in the conditions of water as considered from their diff"erent standpoints. 

 Thus the chemist, the physician, and the trader obviously regard water 

 in diiferent lights, and these and other classes will find their requirements 

 attended to in this work. 



Diagrams of Microscopical Objects for Class Teaching.| — Dr.L. 

 Klein in a long article states that he has derived much advantage from 



* Kevue d'Hygicue, x. (1888) No. 6. f Svo, Braunbchweii!:, 18S9 



X Zcitschr. f. Wiss. Mikr., vi. (1889) pp. 18-32. 



