118 MORPHOLOGIC VARIATION 



mentous types on the one hand, and spherical cells on the other. 

 But it was pointed out that this measure only suffices as long as 

 the cells are symmetrical with regard to both axes. Cells which 

 show terminal or lateral or central bulgings, cells which are branched, 

 wedge-shaped cells, and such unusual types, are not classified by 

 this measure in regard to their asymmetry; they are merely placed 

 in the series according to whether their general form approaches 

 the filamentous or the spherical. Such asymmetrical cells were 

 found to be quite numerous with the cholera organism studied. 

 Nevertheless this method of studying variations in form was carried 

 through with the hope that, regardless of the asymmetry of some 

 of the cells, it would serve to classify them, although roughly, at 

 least to an extent which would give some idea as to the nature of 

 the variations which are occurring. 



A five-day-old culture was inoculated onto agar slants, from 

 which samples were removed at regular intervals for observations. 

 Photomicrographs were prepared and reprojected to give a final 

 magnification of 21,000X, the cells being traced on to cards and 

 measured as described in Chapter III. 



The general character of the morphologic variations of this or- 

 ganism are clearly indicated in Figure 33. This figure has been 

 prepared by plotting the logarithms of the number of cells against 

 the logarithms of the hours of growth. Since the growth curve has 

 been plotted from cell counts made by the direct microscopic method, 

 it does not show the true rate of death, as death of the cells is 

 not registered in these counts until they have autolysed and disap- 

 peared. I have indicated by a dotted line on this graph what I 

 believe was approximately the true death curve as it would have 

 been if plate counts had been made. This estimate may be justi- 

 fied by data to be presented later. Superimposed upon this curve 

 columns of cells have been erected in the order of their area-length 

 indices (those with the lowest index being at the bottom), choosing 

 each tenth cell from the samples of 200 which were measured. 

 The way in which the cells are classified by this value is apparent 

 from inspection of the figure. The longest and most slender cells 

 occur at the bottom, the cells becoming shorter and plmnper as 

 we approach the top of the column, those cells at the very top being 



