36 THE AMERICAN MONTHLY [Feb., 



3. A glass of pure vaseline, paraffine aud a brush. 



4. Infection needles. 



5. A big slide (2x2 inch). 



6. A tin tray (4x3 inch). 



7. A forceps. 



8. A bell-glass. 



All properly sterilized. The moist chamber is about 

 one inch in diameter, and the cover is fastened to the 

 upper end of the glass ring (see Fig. 2, a). The cover 

 is further divided into 16 squares and the numbers 2-17 

 engraved in these. Such moist chambers are made by 

 Mr. Jacob, Hauser Plads, Copenhagen. The beer-wort 

 gelatine is thus made : 100 grammes of beer- wort is 

 heated with 10 gr. of gelatine, and, when near to the 

 boiling point, poured into a hot water funnel (see Salo- 

 monsen, 1. c. p. 467), and filtered. The flame which heats 

 the funnel is kept low and the fluid not allowed to boil. 

 When filtration is over, the gelatine is again heated, 

 poured into sterilized flasks and sterilized in the usual 

 way. 



Now the yeast emulsion is again stirred, and a drop 

 transferred into the (30°C.) gelatine ; the gelatine flask 

 is gently stirred. The big moist chamber is laid down 

 on the tray, cover downwards, and some vaseline applied 

 to the edge of the glass ring pointing upwards. Then a 

 small amount of the gelatine into which the yeast emul- 

 sion was transferred, is taken out with a glass rod and 

 placed at the under surface of the cover facing upwards 

 of the moist chamber, where it is carefully spread out 

 in a thin layer. It is left in this position to become 

 solid, being covered in the meantime with the bell-glass. 

 When the gelatine is solid, the chamber is inverted and 

 the ring pressed down gently upon the big slide. The 

 vaseline prevents the air from passing in and out. A 

 drop of water must be placed on the slide before the ring 

 is inverted and laid down upon it, in order to keep the 



