l894-] NEW-YORK MICROSCOPICAL SOCIETY. 3 



drying of the film. The elements of groups are falsely disturbed, 

 even with those lucky organisms which have escaped injury dur- 

 ing the preceding rough treatment. These may be due to con- 

 traction during drying, and it may affect even forms and groups 

 whose shapes allow them to be pressed down upon a plane sur- 

 face without distortion, such as rods, cocci, chains, and merismo- 

 pedia. The bacteriologist is familiar with the faulted lines and 

 short offsets which signify irregular shrinking during overhasty 

 drying of these delicate watery organisms, and with ghostly 

 lines and spots showing where they have drawn aside or often 

 split entirely away from the cover. But with those forms which 

 must obviously become distorted when flattened upon a plane 

 surface, such as many vibrios and all spirilla, spirochete, staphy- 

 lococcus bunches, and sarcina packets, any process of drying 

 upon covers must be objectionable on account of this distor- 

 tion. Still further, during the drying of ciliated forms in active 

 motion, even at the natural temperature of the laboratory, a seri- 

 ous cause of deformation arises from the writhing toward the end 

 of the drying, especially in forms which become cemented at one 

 end to the cover, while the remainder continues twisting and 

 wriggling into strange, often fractured shapes. These contortions 

 and dislocations can be actually watched during the struggles of 

 the entrapped micro-organisms, and are abundantly displayed on 

 any film of dried spiral bacteria and in numerous published pho- 

 tomicrographs ; spirilla are shown twisted into a curve, spiro- 

 chsete actually bent at right angles, etc. A recent example of 

 such distortion is shown in the photomicrograph of Sp. volulans 

 by Dr. R. L. Maddox, accompanying his interesting paper in the 

 Journal of the Royal Microscopical Society for December, 1893 ; 

 he had already shown the true form in his previous paper in 

 the International Journal of Microscopy and Natural Scietice, iii, 

 (1893), page 233. 



The needed precautions, in my opinion, are, first, that all 

 micro-organisms, including bacteria, should be suddenly killed 

 and fixed before evaporation of the film or any other process of 

 mounting, especially those of active movement ; secondly, that 

 such evaporation should be carried on very slowly and at a low 

 temperature, especially with curved and thick organisms. One 

 purpose of the evaporation, especially the later heating in or over 



