34 ON PROTOPLASMIC CONTINUITY IN THE FLORIDEX. 
repeatedly branched filaments, composed of a single row of cells, 
joined end to end, the whole often forming a delicate feathery 
fr in Ww * . . . 
m 
e. g., C. Rothii, retain this comparatively simple structure through- 
out the whole frond ; but in others some degree of vege pe 1s 
composed of descending filaments, which become adherent to the 
main axis. In C. roseum these filaments arise from the bases of the 
lateral branches, are few in number, and are confined to the stouter 
portions of the stipes and its primary branches. They do no 
become interwoven so as to form a complete investment, but remam 
isolated, and run for the most part parallel to the stronger filameut 
to which they are attached. In C. arbuscula and C. tetragonum, 
which are among the most robust forms, they are much mo 
numerous, and become so closely felted together as to form a cortex 
of considerable thickness compared with the central filament which 
it envelopes. : 
ery little examination of the Callithamnions is needed in order 
to demonstrate the existence of protoplasmic continuity in every 
part of the frond. 
In Callithamnion Rothii the contents of each cell are connected 
joneteaatma ly. with those of the next by a single fine protoplasmic 
thread.. 
ends they swell out considerably, or rather remain uncontracted. A 
single connecting thread of protoplasm proceeds from the centre of 
the other right through the end walls of the contiguous cells. Con- 
tinuity is brought about therefore by means of single threads, and 
not by several such, as occurs in the sieve tubes of Dicotyledons. | 
In the lateral branches continuity o imilar character 18 
equally evident, and it is frequently possible to trace it from ¢e to 
cell along the whole length of a branch. Moreover, the protoplasm 
of the basal cell of a branch is in the same manner connected with 
that of the axial cell from which it arises. So also the cells of the 
cortical filaments have their protoplasmic bodies united, no 
one with another, but also with that of the basal cell of the branch 
from which they take origin. The connecting threads grow with 
‘ ns will have 
any difficulty in convincing himself that the normal condition 15 
one of uninterrupted continuity throughout the whole frond. 
pedioeh 
