188 0. P. Dellinffer 



&^ 



Chromic and Acetic Acid. 

 These two agents enter into strong and weak Flenmiing and the 

 common chromo-acetic acid solution. Chromic acid shrinks and fuses 

 cilia. (PI. I, Fig. 10.) Acetic acid melts them down into a mass of 

 granules. (PI. I, Figs. S, 9.) The combination of the two fuse the 

 cilia so that they appear matted. (PI. I, Fig. 11.) The action of 

 Flemming's solutions has been discussed above. 



Picric Acid. 

 Picric acid enters into Mann's and Rabl's fluid, which I have 

 placed in the HgCl group, and is used with acetic acid. Cilia treated 

 with it are fairly well preserved. The ends are fused, but in some 

 cases the fibrils remain quite distinct nearer the base. (PI. I, Fig. 

 12.) 



Formal. 



Formol in 4 per cent, and 10 per cent, solutions and in a 1 per cent, 

 solution of osmic acid in 5 per cent, formol was used. It is difficult 

 to interin-et the action of this agent. The body of the animal was 

 poorly preserved. In the case of Stylonychia it was broken into 

 fragments. The fibrils of the cilia attached to these fragments 

 seemed well preserved, but the cilia themselves had their identity 

 destroyed. The stronger solution gave the best results. (PI. I, 

 Fig. 13.) 



Platinum Cliloride. 



A 1 per cent, solution of Platinum chloride was tested. It yielded 

 no results to recommend it. 



Conclusions. 



Cilia treated with different reagents show a marked difference in 

 structure. Of the twen.ty-eight agents tested osmic acid (.4 per cent, 

 to 2 per cent. ) is the only one that preserves the cilia in normal condi- 

 dition. Wherever it enters into a killing fluid its influence can be 

 seen. All other reagents produce marked changes in cilia Avhich are 

 characteristic for each reagent. 



In interpreting the structures revealed in tissues killed with these 

 reagents their action on fibrillar structures should be taken into 



