NON-PROTOPLASMIC CELL CONTENTS 95 
CELL-CONTENT Muciace has been found in the leaves of Alee, 
the rhizomes of Triticum, the bulb scales of Squill and Onion and 
in certain cells of many other Monocotyledons, especially those 
containing raphides. 
MEMBRANE MuciLaGE has been observed in Buchu leaves, 
Elm bark, Psyllium seeds, in Althea, Linum, Astragalus, and 
Acacia species, in the Blue-green Algae, and many of the Brown 
and Red Alge. 
Gum.—When mucilage is collected in the form of an exudate 
from shrubs and trees it constitutes what is termed a gum. Chem- 
ically gums consist of glucosidal acids combined either partly 
or completely with calcium, potassium and magnesium. Many 
gums are used in pharmacy, medicine, and the arts. The four 
most important from a pharmaceutical standpoint are: ACACIA, 
yielded by Acacia Senegal and other species of Acacia; ‘T'RAGACANTH, 
yielded by Astragalus gummifer and other Asiatic species of Astra- 
galus; CHERRY Gum, obtained from Prunus Cerasus and its varie- 
ties; and Rep Gum obtained from Eucalyptus rostrata and some 
other species of Eucalyptus. 
Mucilage may be demonstrated in plant tissues containing it by placing sections 
of these in a deep blue solution of methylene-blue in equal parts of alcohol, glycerin 
and water on a glass slide, allowing them to remain in the solution for several min- 
utes, then draining off the stain and mounting in glycerin. Those cells containing 
mucilage will exhibit bluish contents of deeper aspect than other elements. 
18. Frxep Om anp Fats.—These are fatty acid-esters of 
glycerin which are found in the vacuoles of cells or formed with 
the cell walls from which they may be liberated as globules 
upon treating sections with chloral hydrate or sulfuric acid or 
heating them. The fats differ from the fixed oils only in that 
they tend to solidify and crystallize at ordinary temperatures. 
They are quite soluble in ether, chloroform, benzol, acetone and 
volatile oils but insoluble in water, and, with the exception of 
castor oil, insoluble in alcohol. They are readily distinguished 
from the volatile oils in that they leave a greasy stain upon paper 
which does not disappear. Fixed oils and fats take a brownish 
to black color with osmic acid, a red color with alkannin or 
Sudan III and a blue color with cyanin. In Vaucheria, the 
Diatoms and a few of the other Thallophytes, fixed oil is formed 
