ZOOLOGY AHD BOTANY, MICEOSCOPY, ETC. 561 



be substituted : 10 parts acetyl-cellulose, 1 part aluminium palmitate, 

 15-20 parts chloroform, 1 part nitro-benzol. The solution is smeared 

 on a piece of plate glass until it forms a layer about 0'15 mm. thick. 

 When dry it can be peeled off in strips and cut up into slips of suitable 

 size. 



Method of Mounting Bacteria from Fluid Media. — In a communi- 

 cation made at the June meeting, J. A. Hill describes a method of 

 mounting bacteria which is based on the principle of gradually changing 

 the microphytes from aqueous to resinous media. 



One volume of the fluid containing bacteria is mixed with two 

 volumes of a solution containing equal parts of glycerin and absolute 

 alcohol and well shaken. The sediment from this is treated with absolute 

 alcohol several times to ensure the removal of all the glycerin and 

 water. The fresh sediment is treated in a similar way with oil of cloves 

 to remove the alcohol. After this the bacteria are stained by replacing 

 this reagent by a saturated solution of fuchsin in oil of cloves. After 

 about a week an equal bulk of balsam dissolved in benzol (undried 

 balsam 1 part, benzol 1 part) is added, and this mixture is treated several 

 times with the balsam and benzol solution to remove the excess of 

 fuchsin. To the final sediment is added about three times its bulk of 

 balsam or styrax mounting medium, and from this last mixture micro- 

 scopic preparations are made in the usual way. 



. After each step the fluid is allowed to stand until the bacteria are 

 deposited as a visible sediment ; the supernatant fluid is then poured off 

 and the sediment used for the next stage, but the process might be 

 hastened by the use of the centrifuge. 



(6) Miscellaneous. 



Microscopical Examination of Foods and Drugs.* — An up-to-date 

 treatise in the English tongue on the microscopical examination of foods 

 and drugs has long been a desideratum. For about fifty years the student 

 of this important branch of science has had to rely mainly on Hassall 

 or on foreign publications. This reproach has now been removed and 

 a long felt want supplied by H. Gr. Greenish, whose work is specially 

 devoted to instruction in the methods of examining vegetable foods, 

 drugs, and their powders by the aid of the Microscope. 



The author has fully succeeded in his task and is to be congratulated 

 on demonstrating that the Microscope is capable of furnishing with the 

 expenditure of a minimum of material, and also often of a minimum of 

 time, information concerning the substances analysed that cannot be 

 obtained by any other means. 



The contents are divided into twelve sections arranged so that the 

 student may begin with the simplest and proceed gradually to the com- 

 plex ; e.g. starting with starch, the subject matter deals successively with 

 textile fibres, spores and glands, ergot, woods, stems, leaves, barks, seeds, 

 fruits, rhizomes, and roots. There are two appendices which contain 

 very useful information. The first of these is a list of reagents, with 

 their composition and remarks on their use ; the second is a list of the 

 chief varieties of cell-wall and cell-contents, and the means adopted for 

 their identification. The volume is well got up and freely illustrated. 



* J. & A. Churchill, London, 1903, pp. 24 and 321 (168 figs.). 



