ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 679 



little lower (^"-l*^ C). With regard to constancy of temperature, it 

 was found that with a fluctuation of 8° C. in the room temperature, the 

 change in that of the thermostat did not amount to 2° C. With slight 

 fluctuations in the room temperature, that of the thermostat may be 

 regarded as constant. The approximate cost of the apparatus, with 

 thermo-regulator, thermometers, rubber tubing, and lamp, is from 25 

 to 80 fr. 



Milk- Agar as a Medium for the Demonstration of the Production 

 of the Proteolytic Enzyme.* — Referring to papers by E. v. Freudenreich 

 and J. Thoni, and by E. G-. Hastings,! C. Eijkman claims priority in 

 suggesting the use of milk-agar for the above purpose, and in showing 

 that the clearing of this turbid medium depends on the peptonising of 

 the casein and that the casein-splitting enzyme is identical with the 

 gelatin-liquefying one. He argues that while both milk-agar and 

 gelatin are useful in distinguishing between peptonising and non- 

 peptonising colonies, the former had the advantages of not liquefying 

 and of a higher melting-point. The author also advocates the use of 

 the " Diffusionsmetkode " for the demonstration of the production of 

 the fat-splitting enzyme. 



(2) Preparing: "Objects. 



Decantation Method for Cleaning Diatoms. J — S. Broughton re- 

 marks that diatoms should be treated with acid to clear from all soluble 

 matter and afterwards poured into a tall glass jar. Then have ready a 

 siphon, and when the coarser particles have settled down siphon off to 

 within an inch of the bottom ; then empty the sand into another vessel 

 and pour the portion first siphoned off into the glass jar and siphon off 

 again to within an inch of the bottom. Empty the portion left into 

 another vessel and repeat as often as thought desirable, keeping each 

 separate, and at the last let it stand some time, allowing the diatoms to 

 settle down, and then siphon off the clear water. They should then be 

 fairly free from foreign matter. Each lot may then be tested to see if 

 any diatoms are left in, and if so the process should be repeated. 



(4) Staining- and Injecting-. 



Apparatus for the quick and uniform Staining of Serial Sections 

 and for the Treatment of them in Number with Reagents. § — This 

 apparatus, made by R. Jung, of Heidelberg, consists of a glass vessel, 

 70 X 40 x 90 mm., into which fits a carrier for 10 slides made of nickel 

 wire with sloping cross-bars of tin for the -slides to rest on. These cross- 

 bars are turned up at the edge so that the slides cannot fall off. A ring 

 of wire allows the carrier to be lifted out without the fingers coming in 

 contact with the reagent. The glass vessels are very cheap and it is 

 convenient when working to have a number of them, each containing a 

 separate reagent or stain, the carrier holding the slides being lifted from 

 one to the other. 



* Centralbl. Bakt., 2" Abt., x. (1903) p. 531. 



t Op. cit., l t8 Abt., xxix. (1901) No. 22. 



X English Mechanic, lxxvii. (1903) p. 444. 



§ Zeitschr. angew. Mikr., ix. (1903) pp. 57-8. 



