'l894-] NEW-YORK MICROSCOPICAL SOCIETY. 11 



a-educed the number of distorted spirals, apparently all that would 

 have been produced by writhing movements of organisms par- 

 -tially adhering to the cover. Only those remained that were 

 inseparably connected with the process of flattening down spiral 

 forms upon a plane surface. To eliminate this last source of 

 deformation the following process has been devised, which requires 

 some care and patient manipulation, but yields the spirilla in 

 perfect preservation. There is, of course, greater difficulty of 

 studying a spiral under a high magnifying power, and a trouble- 

 some tendency of these spiral forms to intertwist in bunches dur- 

 ing concentration. 



Put a sufficient quantity, say 20 c.c, of the liquid containing 

 the living bacteria in a conical sherry glass or in a urinary 

 deposit tube. Add a little fixative, say 5 c.c. of tannic acid 

 or chromic acid solution, mix by shaking gently, and allow to 

 settle for at least half an hour. Draw off the supernatant liquid, 

 with utmost care not to disturb the light invisible deposit, and 

 wash by a change of sterilized water, allowing to settle as before. 

 Draw off the liquid and transfer the deposit to a number of slides 

 with very shallow cells. Add to each a drop of cold colorant, 

 remove excess by slips of absorbent paper, and wash by changes 

 of sterilized water, removing each by absorbent paper. Then 

 add saturated solution of potassium acetate, cover, and seal. 



Preparations of Amoeboid Organisms. — The difficulty of pre- 

 paring permanent mounts of amoebse, foraminifera, etc., is shown 

 by the rarity of such preparations in all collections and exhibi- 

 tions. The long-accepted but unfounded conviction as to the 

 constitution of such forms of but slightly differentiated and there- 

 fore unstable protoplasm has probably led to discouragement of 

 much effort'in this direction. 



Certes has advised the following process' for preparation of 

 mounts of amcebse. To 30 c.c. of the water containing the liv- 

 ing amoebse about i c.c. of osmic acid solution (i per cent) is 

 added. After settling a few hours, the deposit is washed, con- 

 centrated, stained, and mounted in distilled water containing a 

 trace of osmic acid. 



I have not succeeded by thismethod, partly perhaps on account 

 of the loss of amoebee in the confusedly heaped-up mass of asso- 



1 R. G6rard, Trait6 pratique de Micrographie (1887), 383. 



