March 31, 1905.] 



SCIENCE. 



495 



the dark side, and the tlame is automat- 

 ically turned do^^'n. When the tempera- 

 ture falls to 37° C, the mercury column 

 on the left side makes the contact, turning 

 on the flame. Thus, the temperature is 

 regulated within one degree. Instead of 

 the mercury regulator, one made of thin 

 brass and hard rubber strips securely fast- 

 ened together and arranged between two 

 contact points, may be used. The metallic 

 thermo-regulator may be bought in the 

 open market. 



II., A Simple Method of Making Anae- 

 robic Plates. 



The medium consists of lactose agar, 

 1.2 per cent., which is plated in the usual 

 way and placed on a nivellator. When 

 thoroughly solidified, 7 c.c. of an agar 

 jelly made of 1.2 per cent, agar in distilled 

 water, are poured on each plate making 

 a closely adhering transparent film. This 

 practically accomplishes what the mica 

 plate does, with the advantage, however, 

 that the agar film adheres more closely, 

 covers the medium more satisfactorily and 

 is readily applied. 



Laboratory Expedients. S. DeM. Gage, 

 Lawrence Experiment Station. 

 In the modern public health laboratory, 

 a large amount of routine work of consid- 

 erable detail is often required, and while 

 an increase in the necessary funds is often 

 not forthcoming, constant pressure is us- 

 ually exerted, upon the head, of the labo- 

 ratory to increase the scope of the work 

 and the output of the working force. Un- 

 der these conditions it is often a problem 

 for the working bacteriologist to satisfy 

 all requirements and at the same time to 

 be able to carry on experimental work. 

 The solution of this problem usually lies 

 in systematizing the work and in the use 

 of labor-saving devices whereby the time 

 consumed in routine work may be short- 



ened. It is the purpose of the author in 

 the present paper to describe some of the 

 laboratory expedients at the Lawrence Ex- 

 periment Station as regards both the sys- 

 tem in vogue and the labor-saving devices 

 in use there, under the following headings : 

 (1) Apparatus should stand rough hand- 

 ling, (2) color system and use of tubes of 

 different dimensions for identifying media, 

 (3) dilution bottle filler, (4) apparatus for 

 holding inoculating needles during steril- 

 ization, (5) improvised apparatus, (6) 

 loose sheet system of keeping records, (7) 

 methods of keeping track of samples and 

 experiments, (8) numerical systems. 



A Method for the Direct Microscopical 

 Enumeration of Bacteria: C.-E. A. 

 W^iNSLOw, Massachusetts Institute of 

 Technology. 



One twentieth of a cubic centimeter of 

 the liquid to be examined is discharged 

 from a sterile graduated pipette on a care- 

 fully cleaned cover glass of known diam- 

 eter. This is dried in the air, fixed and 

 stained in the usual way with carbol- 

 fuchsin. The bacteria in ten square fields, 

 0.1 mm. on a side, are counted by the aid 

 of a Sedgwick-Rafter micrometer and the 

 total number determined by multiplica- 

 tion. The method is rapid, easy and ac- 

 curate, but applicable only to fluids like 

 sewage which contain 25,000 or more bac- 

 teria per cubic centimeter. 



The results obtained when pure cultures 

 are examined check very closely with those 

 of the plate method even when the number 

 of bacteria present is decreasing very ma- 

 terially. Thus it appears that dead bodies 

 of bacteria are quickly removed in the 

 presence of other living germs and intro- 

 duce no serious error. On the other hand, 

 sewage and sewage effluents show numliers 

 10 to 100 times as high as the plate count, 

 due mainly to the inclusion of forms which 

 do not grow on ordinary media. 



