O LABORATORY EQUIPMENT 



the virulence of cultures, or bring about many changes in sera. Even 

 diffuse daylight should not be considered as entirely inert. A general 

 rule to be remembered is never to expose any biological reagent, be it a 

 bacterial culture or any form of its derivative, a serum, or any other sub- 

 stance to daylight any longer than is absolutely necessary. If this dictum 

 is followed, one will avoid many a difficulty. 



To conform with this idea, it is wise to have upon the table a small closet into which 

 the cultures and sera can be placed for the time that they are being used. Such a con- 

 venient receptacle can be made out of a large 

 cigar box, painted black inside and out, with its 

 lid replaced by a small black curtain. 



The table or desk at which one works should 

 be near the window, and covered with filter-paper, 

 upon which should come a glass or asbestos plate. 

 Instead of a wooden table it is certainly more 

 elegant, but costlier to have a top plate of glass. 

 Upon the table there should be a Bunsen burner, 

 a microscope, a lamp for microscopic work at 

 night, a dish filled with sublimate or cresol into 

 which the infected substances, old cultures, used 

 pipettes and graduates are placed. 



It is very convenient to have running water 

 and a hood in the same room. Still neither of 

 these is absolutely necessary. As for larger appa- 

 ratus must be mentioned, a thermostat, a mechanism for shaking, a dry sterilizer, 

 a good autoclave, a water-bath, an instrument sterilizer, a water or electrical cent- 

 rifuge, an ice chest, a closet for instruments and glassware, and finally animal cages 

 of the kind that are easily cleansed. 



As for instruments and glassware the following are required: scalpels, scissors, 

 forceps, glass-cutter, sterilizable syringes of various sizes, graduates of 10, 25, 100, and 

 1000 c.cm. capacity each, pipettes of i c.cm. with i/ioo divisions and pipettes of 10 

 c.cm. with i/io divisions, a sterilizable pipette retainer, Erlenmeyer flasks, Petri and 

 KolleV dishes, test-tubes, dark glass flasks, ordinary water glasses, funnels, glass tubing 

 of various sizes, and test-tube racks. Furthermore, a platinum needle and a platinum 

 loop are required. For making a loop of a definite size, and one which can always be 

 referred to, the small instrument devised by Czaplewski is of great help. It consists 

 of four round metal bars i, 2, 3, and 5 mm. in diameter around which the platinum 

 wire can be twisted in order to make a standard loop (Fig. 2). 



All instruments and glassware used for serum work should be per- 

 fectly clean. It is best to have all the glassware plugged with non- 

 absorbent cotton, and sterilized by dry heat. It is never advisable to 

 clean the glassware with strong acids, alkalies or other strong chemicals. 

 If this has been done, the chemicals must be thoroughly removed by wash- 

 ing, as the slightest trace may interfere with the accuracy of some tests. 



All used glassware should at once be placed into a disinfecting solution. 

 For this purpose, lysol, lysoform and cresol solutions are highly recom- 



FIG. 2. Instrument (After Cza- 

 plewski) for the standardization of 

 platinum loops. 



