APPENDIX. 
I. BACTERIAL MEASUREMENTS BY PHOTOG- 
RAPHY. 
Wilson and Randolph' recommend the following 
procedure for accurately measuring bacteria : 
(a) Prepare a drawing about four times the size 
of the desired negative by ruling with ink two sets 
of equidistant lines at right angles to each other, 
making every tenth line somewhat heavier than 
the others. 
(2) Reduce this drawing by photography to such 
a size that the rulings are exactly 1 millimeter 
apart. 
(c) Adjust the photographic apparatus so that an 
amplification of 1000 diameters is secured. Obtain 
this by measuring the image of a stage micrometer 
on the ground-glass screen. 
(7) With this adjustment make a photomicro- 
graph of the bacteria to be measured. 
(e) Superimpose the print of the photomicro- 
graph of the bacteria on the print of the scale, or 
' Journal of Applied Microscopy, vol. ii, No. 11, Nov., 
1899. 
163 
