The Cilium. 187 



resemble the mitoins of Flemming, also those so often figured bj 

 botanists whenever a fibrillar structure is represented. 



Two per cent, osmic + formol : — Cilia treated with this solution 

 are straight and entire. In stylonychia the fibrils seem broken up, 

 but the cilium, as a whole, is well preserved. 



Mercuric Bichloride Group. 



Saturated solution of HgCL in normal salt, HgCL and 2 per cent, 

 osmic acid, equal parts Mann's Fluid, Rabl's Fluid, and HgCl + 95 

 per cent, alcohol. Mercuric bichloride gives better results when used 

 alone than when used in any combination with other agents except 

 osmic acid. In most cases the cilia are twisted, shrunken and broken. 

 HgCl in combination with alcohol gave the poorest results. Fig. 4, 

 PI. I, shows a group of cilia killed with Rabl's Fluid. They are 

 tyi^ical for the cilia killed with any reagent of this group. 



AlcoJiol Group. 



This group contains besides alcohol absolute, 95 per cent., and 50 

 per cent, alcohol in combination with HgCL, osmic acid and acetic 

 acid. Alcohol with the exception of acetic acid gave the most unsatis- 

 factory preparations of all the reagents tested. Cilia were often 

 entirely destroyed. The animal was shrunken and in case of Sty- 

 lonychia broken up. It was often difficult to find pieces for record. 

 PI. I, Fig. 5, shows one of the best groups of cilia found after treat- 

 ment with absolute alcohol. Out of twenty animals only three or 

 four showed any cilia. 



Potassium Bicliromaic Group. 



This agent enters into Mliller's, Zenker's and Tellyesniczky's fluids. 

 Cilia treated with these reagents are shortened. In Stylonychia the 

 fibrills are much crinkled and twisted, in Actinosphaerium the fibrills 

 are granulated. Zenker's fluid, which is used more than any other of 

 the group, gives the best results, but with it the ends of the cilia are 

 rounded and fused. (PI. I, Fig. 1.) 



