SPECIAL METHODS. 211 



the same individual. In the mesophyll of Avena orientalis 

 they are of about the same size as the chloroplasts (cf. Fig. 

 46, o\ 



According to Monteverde, they lie in the protoplasm and 

 are mostly isotropic, but in many plants are also doubly re- 

 fractive, especially in dried tissues. In the grasses this 

 double refraction disappears, according to Monteverde, when 

 sections are warmed to 5O-55 C. in water, but reappears 

 after a few minutes. 



These oil-bodies generally behave with reagents like true 

 fats. I have found them, especially in Oplismenus imbecillus 

 and Elynms giganteus, insoluble in cold or hot water or al- 

 cohol, but soluble in ether, petroleum-ether, chloroform, 

 xylol, and clove-oil. They are colored brown or black by 

 osmic acid. They are deeply stained by cyanin ( 1 10) and 

 alcannin ( 109). On the other hand, they remain completely 

 unchanged in form after 24 hours in a mixture of one vol- 

 ume of concentrated caustic potash solution and one volume 

 of ammonia solution, and seem not to be capable of saponifi- 

 cation in this way(cf. 112). 



370. Besides these, Monteverde found in grasses contain- 

 ing crystals and in those free from them, drops of an oil-like 

 appearance, but of wholly unknown composition. They in- 

 crease in size in water, glycerine, and dilute acids only by 

 the formation of vacuoles, but gradually dissolve in alcohol. 

 After a long stay in water, they become insoluble also in al- 

 cohol. They dissolve with swelling in strong mineral acids and 

 acetic acid, and instantly in caustic potash, ammonia, ether, 

 chloroform, and chloral hydrate. They are not stained by 

 alcanna tincture, but easily so by aniline dyes. They be- 

 come brown with iodine. Monteverde considers it probable 

 that they consist chiefly of resin. 



I will mention here the structures observed by Lundstrom 

 {I) in the epidermal cells of various Potamogeton species, 

 which he regards as oil-drops, although, according to his 

 statements, they are soluble in very dilute alcohol. 



