5^r 
Form of Hormidium flctccidum , A. Bratm. 
same localized region of thickening substance within the fork of the lamellae 
of the septum became deep purple, and could be traced as a continuous 
girdle round the filament, embedded in the septum some little distance 
within the ‘cuticle’ (Fig. 3, G). The stained substance appeared in great 
bulk in drawn-out septa (Fig. 3, h). When splitting was in progress, as well 
as occasionally in intact septa, the whole middle portion of the septum, 
between two unstained lamellae, became deeply coloured (Fig. 3, E and 1). 
A debris of stained particles was occasionally seen in contact with the new 
end cells of pieces of filament recently detached. 
The results produced by the above stains show that in the material 
examined the cuticle was somewhat mucilaginous, especially where obviously 
disintegrated. The thickening substance in the septa was usually mucilagi- 
nous near the periphery, and in certain cases formed a continuous plate of 
mucilaginous material through the middle of the septum. Also, mucilaginous 
substance was generally associated with the separating lamellae of splitting 
septa. 
For comparison, similar observations were made on material which had 
been growing for some weeks in nutritive solution and showed no indication 
of splitting. Here the ‘ cuticle ’ of the longitudinal walls was not distinguish- 
able except opposite the septa, and there was no degeneration. The two 
distinct lamellae of the septa were often apparent, diverging a little before 
joining the longitudinal wall and often dissociated to a small extent in the 
central region, thus rendering the septum slightly biconvex (Fig. 3, j). 
There was always a thickening substance between the two lamellae, but 
this did not respond to methylene blue and Ehrlich’s haematoxylin so 
readily as that in the material examined above. With both these stains, only 
small particles within the fork at the edge of the septum and scattered in 
the thickening of the central region became coloured (Fig. 3, J, K). 
From the preceding data the following conclusions may be drawn : 
The ‘ cuticle ’ tends to undergo a certain mucilaginous degeneration and to 
become especially thin opposite the septa. There is normally secreted in 
thickening septa a mucilaginous substance, which may form a continuous 
layer throughout the septa. This substance is very generally associated 
with splitting septa and frequently with the end wall of newly separated 
pieces of filament. 
An examination of partially split septa, which were numerous in the 
material described on p. 527, furnished the following details regarding the 
process of splitting. The latter was usually initiated by the disintegration 
of the ‘cuticle’ at a septum, but sometimes the lamellae of the latter first 
separated at their edges, and the ‘ cuticle ’ adapted itself to the new shape 
by stretching, until it ultimately broke across. Partial splittings were 
common in bent filaments, being restricted to the portions of the septa on # 
the outside of the curve. They were, however, occasionally present in 
