410 Prof. H. Karsten on the Formation, 
If, notwithstanding, I now find, after the repeated and most 
careful examination of this interesting plant, that the law of 
development laid down by me is followed also in the formation 
of the cells of its tissue, particular difficulties must indeed have 
been thrown in the way of the recognition of the true phenomena 
by the structural conditions of this plant. 
And it is undeniable that such hindrances do exist in the mode 
of development of the cells of this plant,—dependent, in the first 
place, upon the existence of a large number of secretion-cells m 
the vegetation-cells concealing their youngest phases and render- 
ing observation difficult; secondly, upon the fact that in the 
tissue-cells the youngest joints do not, as is commonly the case, 
remain a long time undeveloped and exhibit their characteristic 
nucleus ; and thirdly, upon the circumstance that the sutcessive 
endogenous development in this plant proceeds in a high degree 
even in the secretion-cells, whereby the distinctive characters of 
the vegetation- and of the secretion-cell become confused and lost. 
It is partly by these circumstances that the recognition of the 
true developmental processes in this plant has been rendered 
difficult (as indeed Jessen has shown by the communication of 
his observations on various Algze), but partly also by the method 
of investigation, in which chemical reagents have been employed 
as physical aids. 
In the following account I shall relate my observations in the 
order dictated to me by the opportunities I had of making them 
upon the developing plants. 
It has been noticed, in the case of several Algee, that individual 
cells detach themselves from the cell-tissue of the organism, be- 
come free like gonidia or the buds of more complex plants, and 
at length produce perfect individuals. This phenomenon (which 
takes place in nature under certain, though as yet not fully un- 
derstood, conditions) may be artificially produced in the Clado- 
phora glomerata, and probably also in the other Confervee allied 
to it. 
On cutting a Cladophora glomerata longitudinally into small 
pieces, so that a cell remains in each portion uninjured between 
two cut ones, and on placing such sections in water (Pl. VI. 
figs. 80 & 48), a portion of the mucilaginous granular contents 
is seen to escape from the cut ends of the cells, whilst another 
portion will become progressively changed and dissolved by the 
intruding water. The single uncut cell, however, resists the 
action of the water at its internal transverse septa, now freely 
exposed, as well as at the cuticle clothing its lateral walls, which 
does not permit diosmosis to take place in sufficient amount to 
exert an injurious action upon the assimilative activity of the 
enclosed cell. The cell thus isolated proceeds in its development, 
