ROUTINE TESTS FOR THE DESCRIl'TIN E CHART V49-3 



entered at the bottom. By the use of right-hand margin and bottom 

 edge, a long series of charts may be compared, one on top of the other, 

 by ghincing only at these two edges. The back of the Slaii(hird 

 Chart is now reserved hirgely for supplementary data, nearly all of 

 which is summarized on the front. (See first insert, following p. 12.) 

 The increasingly large number of tests called for in the study of 

 bacteria has resulted in making a somewhat complicated chart. 

 Although all these tests may be needed in some research work, they 

 plainly are not needed in the use of the chart for instruction pur- 

 poses. To meet the demand for a simpler chart for use in teaching, 

 a new form known as the Descriptive Chart for Instruction was 

 published in 1939. This chart is designed to fit a standard note-book 

 for 11 by 83^ inch sheets. (See second insert, p 12.) In numerous 

 research laboratories, also, this chart is proving more useful than the 

 Standard Chart, because of its flexibility and the amount of space 

 available for special tests. 



Determining Optimum Conditions for Growth 

 Before beginning the study of any pure cidture, it is important to 

 know something about the growth requirements of the organism. If 

 the organism in question does not grow in ordinary media, either 

 because it is an obligate parasite or because it requires the complete 

 absence of oxygen or of organic matter, it ob\'iously cannot be studied 

 by the methods called for on the Descriptive Chart. For such organ- 

 isms the investigator must use his own methods of study, and may 

 record the results in the blank space at the bottom of the back of 

 the Chart. For those organisms that grow on ordinary media, methods 

 must be varied according to whether the organisms grow better in 

 liquid or in solid media and at high temperature or low temperature. 

 It is important, therefore, that before studying an unknown culture 

 which is able to grow in laboratory media, these two points in regard 

 to growth requirements be determined. (As pointed out in Leaflet 

 II, many such media are now available in dehydrated form.) 



After these growth peculiarities are determined, it is possible to 

 proceed with the study of an organism under 0})tinium conditions. 

 Space is left on the Chart under all of the procedures listed where 

 the medium used and the temperature of incubation can be recorded. 

 So far as possible the same imiform set of conditions should be used 

 throughout the entire study of one organism. If, for example, one set 

 of tests is made on solid media at 25°C, the other tests should be 

 made likewise. Leaving out those organisms referred to above which 

 require special conditions of study, and other organisms of peculiar 

 growth requirements, such as the thermophilic bacteria, there are 

 four different sets of conditions that wall suit practically all bacteria. 



