UNORGANIZED CELL-CONTENTS. 
31 
composing them. The membrane is a plasma mem- 
brane and, while soluble in water, remains intact on 
examining sections in any of the fixed oils, as cotton- 
seed oil. Usually seeds which contain aleurone are 
rich in fixed oils, and if this oil is first removed by 
placing fresh sections in alcohol, or alcohol and ether, 
the subsequent study is facilitated. If the sections 
thus treated are mounted in water, the membrane 
gradually dissolves, leaving the crystalloids, globoids 
and calcium oxalate. On adding a OT to 1 per cent, 
solution of either sodium or potassium hydrate, the 
crystalloids dissolve, the globoids and calcium oxalate 
crystals remaining unaffected. The globoids may be 
dissolved by the use of a 1 per cent, acetic acid solu- 
tion, or concentrated solutions of ammonium sulphate 
or monopotassium phosphate. The calcium oxalate 
remaining may then be treated with hydrochloric 
acid in the usual way. 
SUBSTANCES WITHOUT DEFINITE FORM. 
1. MUCILAGES AND GUMS. 
By the terms mucilages and gums are meant those 
substances which are soluble in water, or swell 
very perceptibly in it, and which, upon the addition 
of alcohol, are precipitated as a more or less amor- 
phous or granular mass. Mucilage originates in the 
plant as a cell-content, or as a modification of the 
wall. In the former case it arises as a product of the 
protoplasm, or it may be a disorganization product of 
some of the carbohydrates of the cell-contents. When 
it occurs as a “ membrane mucilage,” it owes its 
origin to several causes: either to a secondary thicken- 
ing of or an addition to the cell wall, or a metamor- 
phosis of it, at least in part. In the latter case it 
may arise either as a disorganization product of the 
