J. M, MACFARLANE ON VEGETABLE AND ANIMAL CELLS, 589 
easily to notice the nuclei than if prepared by the osmic acid process. It is to 
be understood that while the multinucleolar phase has been seen in all cells, 
the same cannot be said of the multinuclear phase, except in the internode of 
the stem, which invariably has a greater or less number of nuclei. Only here 
and there in the other parts of the plant have I detected multinucleated cells. 
Whether this be due to imperfect histological examination or to the more 
common presence of one nucleus only, cannot as yet be fixed. 
Having studied Chara, I examined the genus Natella, which, while closely 
allied to the former, is much simpler in structure. The internodal cells both 
of the stem and leaf elongate greatly after their formation, while the nodal cells 
scarcely increase at all. Though they all alike become multinucleolar, the inter- 
nodal cells only progress to the multinuclear condition, but this is of a most 
pronounced character, since in internodes still elongating I have counted thirty 
to seventy nuclei. 
These observations enable us to understand and group together facts which 
have been more or less isolated. To do so we will take up the structurai parts 
in detail. 
Endonucleolus.—Though I have not been able always to follow the fate of 
the endonucleolus in Chara, owing to many of my preparations being pretty 
deeply stained, from all that I have seen of it Iam led to conclude that division 
begins with it. 
Nucleolus.—The nucleolus has been shown to pass through a most precise 
and very remarkable series of changes, which force upon us the conclusion 
that it isa most important part of the cell. But, as Dr Hamitron has remarked 
in going over some of these points, a belief in its reality and importance is, to 
a great extent, a return to former ideas. If we refer to SCHLEIDEN’S classic 
paper on cell structure,* we learn that he regarded it as “a small sharply 
defined body.” But to Narcexrt is due the merit of pointing out its very wide 
occurrence and definite nature, for, after an examination of many Cryptogams 
and Phanerogams, he is ‘inclined to set forth generally and to claim as an 
essential character of the nuclear vesicle, that it contains one or more nucleoli.” 
Again, he says, “as to the structure of the nucleolus, in my opinion, nothing 
universal or precise can as yet be said. In some cases they appear to be merely 
accumulations of mucilage. In others a membrane which surrounds them is 
wholly unmistakable. In every case it is certain that they always appear with a 
clearly defined margin. This circumstance speaks strongly in favour of the 
assumption that they, like the nuclei, are enclosed ina utricle. Since if they 
were merely agglomerated mucilage, we should have nucleoli, the substance of 
which would pass gradually into the mucilage of the nuclear vesicle, and which 
* MU.uer’s Archiv., part ii, 1838. 
+ Ray Society Bot, Papers, 1845 (Trans.). 
