74 BOTANICAL MICROTECHNIQUE. 



In various other objects, as, for instance, in sections from 

 the endosperm of Bertholletia excelsa or from the cotyledons 

 of Helianthus annuus, I obtained much larger sphaerocrystals 

 or groups of them, which were often not to be distinguished 

 from oil-drops by ordinary illumination, but behaved quite 

 like sphaerites in polarized light. 



Whether these differences are to be attributed to chemical 

 differences between the various fats, or whether all fatty 

 oils yield crystalline formations under the treatment de- 

 scribed, must be determined by further researches. It is 

 also still to be shown whether other compounds, especially 

 many ethereal oils, do not show the same relations. 



4. Wax. 



113. The name wax is commonly given to the substance 

 which covers those parts of many plants which are above 

 ground and gives them a characteristic bright blue-green 

 color. 



Morphologically, three distinct kinds of wax coverings 

 may be distinguished. In the first, the wax forms a com- 

 plete coherent crust over the epidermis; in the second, it 

 occurs in the form of rounded granules ; in the third, in the 

 form of small rods. 



Concerning their chemical relations it may be remarked 

 that, according to Weisner's investigations (I and II), these 

 wax coverings contain true fats, free fatty acids, and a 

 number of other substances. But in general the study of 

 their chemical constitution has to do with little known 

 compounds. 



114. The wax coverings are characterized microchemi- 

 cally, as DeBary (I, 132) first showed, by being always 

 insoluble in water, though they melt together into drops in 

 boiling water, since their melting points are all below 100 

 C. They are also insoluble or hardly soluble in cold alco- 

 hol, but are always completely dissolved by boiling alcohol. 

 In ether some of them are readily soluble ; others are not 

 soluble or very slightly so. On heating in a solution of 

 alcannin in 50$ alcohol, they run together into red drops. 



