5 2 ° 
Piercy . — The Structure and Mode of Life of a 
splitting septa ; occasionally, the entire remaining portion of a partially split 
septum became blue, but usually, with these and intact septa, only a restricted 
area of the thickening substance within the fork of the lamellae was affected. 
Fig. 3. A, bend in a filament, causing ‘ cuticle ’ at the concave surface to become corrugated. 
B, biconcave septum in optical section. C, thickening substance of septum drawn out between two 
cells. D, disintegrating ‘ cuticle ’ stained by methylene blue. E-f, septa stained by Ehrlich’s 
haematoxylin, in optical section; E, F, splitting septa in which. the middle layer of the intact part 
and the debris of thickening substance adhering to the dissociated part have taken up the stain ; 
G, shows stained area within fork of the lamellae of the septum ; h, shows stained thickening 
substance in a drawn-out septum. I, entire middle' layer of an intact septum stained, j, k, septa 
from filaments growing in nutritive solutions stained with Ehrlich’s haematoxylin. l, septum 
in which splitting is nearly accomplished. M, cell recently detached by splitting of filament, 
widened at its free extremity. N, curved filament which has contracted on becoming dry, showing 
the ‘ cuticle ’ dissociated from longitudinal wall on convex surface, and corrugated on the concave 
surface of bend, c., 1 cuticle ’ ; m., thickening substance of septum ; /., lamellae of septum; w., longi- 
tudinal wall”; other lettering as in Fig. 1. (a, b x89o;c-k xi,50o;l xi,30o;m x 480; n x 1,150.) 
The longitudinal walls remained unstained. Treatment with Ehrlich’s 
haematoxylin for about seven minutes, and rapid rinsing in water sub- 
sequently, produced results (Fig. 3, E and F) similar to those obtained with 
methylene blue, the longitudinal walls as a whole being still unstained, 
though the cell-contents had become deeply coloured, while usually the 
