374 



SUMMARY OF QUERENT RESEARCHES RELATING TO 



The best temperature for cultivation is 50°-55° F. "When plasmodia 

 are sufficiently developed, the withholding of food and gradual lessening 

 of moisture induce the formation of sporangia. 



To preserve sporangia for exhibition under the Microscope they must 

 be set aside in a dry place until all moisture has evaporated, and should 

 then be mounted in air, in deep glass cells. A good plan is to stick a 

 small ledge of cork to the slip, a little below the centre of the cell, and 

 stick the specimen upon the cork, in its natural position, supported by a 

 portion of the leaf, bark, or other substance on which it has been found ; 

 shellac, or any other adhesive material commonly used, will serve the 

 purpose : and, when quite dry, all can be closed in with a cover-glass. 

 Such slides, however, must be protected from rough treatment, as a fall 

 or jar is likely to cause frail sporangia to fall to pieces. 



When under the Microscope, mounted in the manner described, the 

 specimens should be brilliantly illuminated as opaque objects ; and 

 pleasing effects can be produced by placing behind the slide, and there- 

 fore out of focus, a piece of coloured paper, or white paper with a piece 

 of blue or green gelatin laid upon it, to furnish a suitable background. 



A New Apparatus for Studying Bacterial Enzymes.* — S. L. 

 Schouten has devised the following method. The apparatus (fig. 65) is 



^v-> v^ 



Fig. 65. 



of glass, the dotted portions represent wool-corks, the line-shaded por- 

 tions being rubber tubes. In tube A is a little glass powder on to which 

 is poured a nutrient solution, in which the organism is to be cultivated ; 

 in F, G, F', G', is the material on which the enzyme is to act, and C 

 contains water ; the whole is steriHsed, and the tube A inoculated. 

 When sufficient growth has taken place water is poured from C on to 

 the cork E until it is saturated, then some of the medium in A is poured 



* Centralbl. Bakt., 2te Abt., xviii. (1907) p. 95. 



