212 . Appendix. 



in diameter, and of medium weight. Tubes to be filled 

 with gelatin for quantitative work may be those described 

 as 6 in. X f in. "heavy." 



The standard loop for making transfers shall be pre- 

 pared as follows: 



Bend the end of a piece of No. 27 platinum wire about 

 10 cm. long over a bit of No. 10 wire, and fasten the loop 

 thus formed into a glass rod to serve as a handle. A 

 loopful of culture shall be interpreted as meaning all the 

 fluid that the loop can hold. That is, the fluid shall 

 form a bi-convex body and shall not be simply a film 

 covering the space in the loop. 



The standard fermentation tube shall be a tube 1.5 cm. 

 in diameter, bent at an acute angle, closed at one end 

 and provided with a bulb at the other which is large 

 enough to receive all the liquid contained in the closed 

 portion. The length of the closed end of the tube shall 

 be about 8 cm. 



INCUBATION. 



There shall be two standard temperatures of incuba- 

 tion for special work, namely, 20 C. and 37 C., the 

 first corresponding to ordinary room temperature, the 

 second to blood heat. The temperature of the incu- 

 bators shall not be allowed to vary from these two stand- 

 ards by more than i C. in either direction. 



The atmosphere of the incubator shall be kept moist, 

 preferably near the point of saturation. The incubator 



