214 BOTANICAL MICROTECHNIQUE. 



and 347) give very good results. Especially after fixing 

 -with nitric acid, preparations may be pretty easily obtained 

 in which the granula are still deeply colored, while the much 

 larger chromatophores are wholly decolorized. I can recom- 

 mend the leaves of Trade scantia albiflora as suitable objects 

 for study, as they contain comparatively large granula, 

 especially in the spongy parenchyma (cf. Fig. 48, g). 



[Crato (I) has lately observed, in Chcetopteris and other 

 plants, certain structures, hitherto included under the gen- 

 eral term microsomes, which he regards as special organs 

 of the cell and calls physodes. For further details, his 

 account of them may be consulted.] 



8. The Cilia. 



376. The cilia, which occur on most of the freely motile 

 lower organisms and are always directly connected with the 

 protoplasm, are often so fine that during their active motion 

 they can be recognized with difficulty or not at all, even with 

 the best objectives. 



377. In many cases the cilia may be made better visible 

 by bringing the organisms to rest by quickly killing them. 

 For this purpose, the vapor of osmic acid or \% osmic acid, 

 \% chromic acid, or the solution of iodine and potassium 

 iodide may be used. The cilia often appear sharply, also, 

 If a drop containing the organisms be allowed to dry upon 

 the slide. 



378. If the position of the cilia is to be determined while 

 in motion, fine granules of carmine, or the like, may be 

 added to the fluid containing the organisms, according to 

 the method proposed by Butschli (I, 7). The movements 

 of these granules will show the cilia-bearing end. 



379. Recently staining methods have also been used for 

 the recognition of cilia. 



Migula (I, 76) obtained a fine staining of the cilia of 

 Gonium pectorale by using the following method : A very 

 small drop of a concentrated alcoholic solution of cyanin 

 was added to the living specimens, and, after a time, enough 



