METHODS OF HEALING IN SOME ALGAL CELLS 
Susan P. Nichols 
(Received for publication April 30, 1921) 
Introduction 
At the present time very little is known regarding the method of healing 
in mature plant cells. The researches of Kite ('13), Chambers ('17), and 
Seifriz ('18) have been devoted principally to invertebrates and to ova. 
Their interest was directed to the study of the structure and character of 
the cell contents as revealed by dissection, rather than to the later reactions 
to the injury. The repair of the injury and subsequent growth of a few 
ova have been recorded, but these studies did not involve the rebuilding 
of plant cell walls. The difficulty of piercing plant cell walls seems to have 
prevented work along this line. 
Kite, in his initial work, dissected Spirogyra and found that 
The cellulose wall is enormously cohesive. It is cut or punctured with extremely fine 
Jena glass needles with considerable difficulty. The outer surface is covered by an almost 
invisible soft gel, . . . The protoplasm of plant cells is much more dilute or less rigid than 
that of animals. 
Chambers used the. ova of Fucus, which did not involve the study of 
wall or plastids. 
Seifriz, in his studies of plant structure, avoided forms with definite 
cell walls, with the exception of pollen tubes, the walls of which are extremely 
delicate. In speaking of oogonia of Fucus, Seifriz states : 
If these oogonia are teased out at a very early age they can be entered by a sharp needle. 
Very soon, however, the outer wall (exochiton) becomes too hard to be penetrated. 
Topler ('03) in some experiments on injured or sectioned cells of Bornetia 
secundiflora found that the protoplasm remaining in a wounded cell would 
form a new wall. The amount of protoplasm lost in his experiments was 
sufficient to cause the remaining protoplasm to contract from the old wall 
against the adjacent uninjured cell of the filament, where it sometimes 
assumed an abnormal shape. A new wall was then developed by this 
protoplasm, forming a new cell. 
The present article deals with some of the reactions of mature plant 
cells when punctured. 
Material 
Both fresh- and salt-water algae were used in the following described 
experiments. The fresh-water forms were collected near Oberlin, Ohio, 
and grown in culture in the laboratory. The marine forms were studied 
18 
