1894J NEW-YORK MICROSCOPICAL SOCIETY. 13 



Preparations of Jnfiisorians. — Excellent methods have been 

 devised for preparations of these organisms by Certes, Kiinstler/ 

 Fabre-Domergne/ and others. My method, by evaporation, is 

 perhaps only applicable to the smaller forms. With the larger, 

 hitherto, in my experiments, the dried organisms become injured 

 by bursting and outflow, or by irregular contraction, the contour 

 of the sac even parting often from the cilia. With smaller forms 

 the process specified for bacteria may be followed, with use of 

 the special fixative found by trial best suited to each species — 

 e.g., concentrated solution of osmic acid (Kiinstler), boiling solu- 

 tion of tannic acid, 3 per cent (C. O. Sonntag),^ equal parts of 

 osmic acid solution (i per cent) and acetic acid (20 per cent), 

 Kleinenberg's solution, alcohol, chromic acid, picric acid, etc. 

 The dried minute infusorians, like the smaller rhizopods thus 

 prepared, seem as well adapted for study as the bacteria in a 

 dried film, as they display the cilia, sac, vacuoles, nuclei, enclosed 

 food particles, etc., in a satisfactory state of preservation, with 

 no visible distortion. 



In place of drying the larger infusorians, the following method 

 has been found useful. They are first narcotized in the drop of 

 water, under observation with a low power, after the method of 

 E. A. Schultze,* by addition of a neutralized solution of hydroxyl- 

 amin hydrochloride (0.25 to i per cent), or by Rousselet's 

 method '" for rotifers, by addition of a weak solution of cocain 

 hydrochloride. At the moment the cilia cease to move the 

 organisms are suddenly killed, after Schultze's method, by add- 

 ing a drop of alcohol, picric acid, or acetic acid ; or, after Rousse- 

 lefs method, by a drop of osmic acid solution (i per cent), or 

 by a drop of Flemming's mixture (15 parts of chromic acid, i-per- 

 cent solution ; 4 parts of osmic acid, 2-per-cent solution ; and i 

 part of glacial acetic acid). The organisms are then washed and 

 stained, as described in preparations of spirilla. The use of 

 Loeffler's mordant on the infusorians is found of the highest 

 advantage, as the cilia become readily absorbent of stain to any 

 depth of coloration desired. A serious difficulty is found in the 



1 Jour, de Micrographie, x. (1886), 59. 



2'' Notes techniques sur I'etude des Protozoaires," Ann. de Micrographie, ii. C1889), 545. 



3 Internal. Jour, of Mic. and Nat. Sci., iii. (1893), 306. 



* This Journal, viii. (1892), 28. 



6 Jour. Quek. Micr. Club, 2, v. (1893), 205. 



