78 BACTERIAL DISEASES OF PLANTS 



Cotton and Gauze. — The best surgeon's roll-cotton is not 

 too good for plugging test tubes and flasks. Surgeon's gauze in 

 bolts should be on hand for coarse filtering and various other 

 uses. 



Balances. — There must be coarse pan-balances for ordinary 

 weighings, and fine balances for the more delicate operations, 

 these latter usually under lock and key, especially where careless 

 persons are wandering about. The Becker chemical balance, 

 and the Kny-Scheerer analytical balance (Sartorius model) are 

 very good. 



Dry Ovens. — The best dry oven I know is Lautenschlager's. 

 This gives in all parts a very uniform temperature, and requires 

 a minimum of watching. 



Steamers. — The Boston Board of Health steamer, made by 

 the Arnold Steam Sterilizer Company, Rochester, New York, 

 is recommended. 



Autoclaves. — I use two kinds: an upright autoclave made in 

 Paris by P. Lequex, known as the Chamberland-Wiesnegg 

 (depth 17 inches, diameter 13 inches), and a larger horizontal 

 apparatus made by the Kny-Scheerer Company, New York, 

 N. Y. The latter has a capacity of twelve 2-liter flasks, the 

 depth being 28 inches, and the inside diameter 20 inches. By 

 adjusting a valve, air is pumped out of the inner chamber and 

 by another turn steam is allowed to enter whereupon the two 

 pressure gauges should register alike. The steam may be gener- 

 ated by gas flames or may be taken directly from the engine- 

 house boiler. I prefer gas, which is more easily controlled. 



Centrifuges. — Milk and other fluids frequently require cen- 

 trifuging, and for this purpose a centrifuge holding at least half 

 a liter is necessary. This may be propelled either by steam or 

 by electricity. I formerly used a very good electric centrifuge 

 made by Lautenschlager but the gearing required so much space 

 that I have abandoned it for a much more compact and equally 

 serviceable machine made by the International Instrument Com- 

 pany, Cambridge, Mass., using electricity as the motive force 

 (Fig. 52). Our instrument is so compact that it occupies only 

 some waste space behind a door. It is bolted to a thick block 

 of concrete (18 by 26 by 30 inches) resting on the floor. It is 



