178 Report OF DEPARTMENT OF BACTERIOLOGY OF THE 
have confirmed this belief. Moreover, these recent studies have 
Shown that the inner lamellae contain varying proportions of 
pectose or pectic compounds intermingled with the celluloses. 
The relation of these is evidenced if Schweitzer’s reagent, which 
is a cellulose solvent, be carefully applied, when it will remove 
the cellulose and leave the pectic skeleton. The converse oc- 
curs, as will be shown in detail later, when the carrot-rot 
enzym acts upon the walls, removing the pectic elements and 
leaving the cellulose. 
Mangin’s studies led him to conclude that in the early stages . 
of its development the wall consists more largely of the less 
soluble pectose, whereas in the mature wall the calcium pec- 
tate predominates in the original plane, i. e., the middle 
lamella, and the pectose which occurs is in the inner lamellae, 
i.e., nearer the cytoplasmic layers. The proportion of cellulose 
becomes increasingly predominant, however, as one passes 
from the middle to the inner layers. Although this is the case, 
there probably occurs, even in the young walls, a thin sheet of 
calcium pectate invisible under the microscope but evidenced 
by the splitting of the walls along the middle plane under the 
action of pectate solvents. With the increasing age of the cell 
this layer is thickened and more clearly defined until it be- 
comes plainly visible in the mature cell as the middle lamella. 
The splitting of the lamella along the middle lane as a result 
of the tensions set up between the growing cells indicates that 
this apparently homogeneous plate is in reality from the be- 
ginning a double sheet, one-half of which originated with each 
daughter cell following mitosis. 
Fremy’s enzym, pectase, which is especially abundant in 
growing tissues, is supposed to function’® in this lamella for- 
mation by converting the insoluble neutral pectose of the inner 
lamellae into the more soluble pectine and ultimately into 
pectic acid, which then passing, perhaps by diffusion pressure, 
to the outer surfaces of the inner lamellae, i. e., to the planes 
where this meets the middle lamella layers, is there combined 
with calcium to increase this middle lamella substance. This 
appears homogeneous, but as will appear later is, like the 

asCoT Green. 1901: 297-306, 
