650 
Notes. 
course modifies this to some slight extent. There seems evidence that this type of 
division can, under certain circumstances, be continued for some time during the life 
of the young plant (cf. below). 
In a large proportion of the young plants the lower surface of the basal cell was 
more or less completely enveloped by a hyaline substance (Fig. 61 b, e), which was 
sharply delimited towards the periphery. This substance is quite unaffected by 
Iodine and Chlor.-zinc-iodine, whereas Vesuvin stains it a dark reddish-brown colour, 
thus indicating its mucilaginous nature ; at the same time the cell-walls take on an 
almost equally deep tint. This dense mucilaginous mass, which is thus found on the 
lower side of the basal cells, undoubtedly serves to attach these filaments, which are 
otherwise but badly suited for attachment. The occurrence of mucilage in this 
position is not without parallel in other species of Oedogomum, for the branched 
processes of the attaching-disc are in some cases mucilaginous at their tips, as are also 
the ends of the rhizoids 1 ; in many species of Oedogomum, however, some ferric salt of 
iron appears to play a part in the attachment of the young plants, acting as a kind 
of cement 2 . I am not prepared to say in what way this mucilage is developed, i. e. 
whether it is formed by excretion or by the gelatinization of the cell-wall, but the 
former seems more probable. 
In a very large percentage of the young plants examined, the apical cell pre- 
sented a peculiarity, which I do not remember having seen recorded as yet; this 
phenomenon was generally wanting in the very young, few-celled filaments, although 
indications of it were occasionally also to be observed here. Instead of the apical 
cell having a rounded or pointed extremity, it was provided with a longer or shorter 
cap of cell-wall substance with square corners, so that the apex of the filament had 
a rectangular appearance (Fig. 61 a, c). This cap fits tightly over the terminal cell of 
the filament, which is generally slightly pointed and thus insinuates itself into a 
V-shaped incision in the cap. Examination of this cap under a high power shows 
that the cuticle (i. e. the outer layer of the cell-wall) extends right round it, and that 
its main mass is constituted by a not very highly refractive substance, enclosed 
between this cuticle and the inner layer of the cell-wall, which is quite conspicuous 
as a membrane limiting the apex of the cell contents of the terminal cell, i. e. the 
main mass of the cap consists of a rather darker substance enclosed between the 
cuticle and the bright inner layer of the cell-wall. Similar caps were occasionally 
also observed in the course of the filaments 3 ; this was, however, rather rare, and 
they were never seen to attain the dimensions of the terminal caps (cf. Fig. 61 d). Their 
occurrence quite agrees with the explanation of their origin given below. Under 
a high magnification these caps are seen to have a very distinctly stratified structure, 
recalling the usual cap-structure of the cells of Oedogomum. This undoubtedly also 
explains their origin. The terminal cell has again and again formed cellulose- 
1 Wille, Uber das Keimen der Schwarmsporen bei Oedogomum, in Pringsh. Jahrb., vol. xviii, 
1887, p. 458; Pringsheim, Morphologie der Oedogonien, in Pringsh. Jahrb., vol. i, 1858, p. 55; 
Fritsch, Structure and Development of young plants in Oedogonium , in Ann. of Bot., vol. xvi, 
1902, p. 471. 
2 Fritsch, loc. cit., p. 473. 
3 I have also noticed such intercalary caps in other species of Oedogomum, although no notes 
were made on the subject at the time. 
