26 Mr. H. J. Carter on the Development of the Root-cell 



comes invisible, or very faint under the action of sulphuric acid, 

 iodine fails to restore its form, or render it more distinct ; and 

 in no instance have I ever been able to produce the characteristic 

 blue colour of starch in any part of the nucleus. 



We now come to the offices of the nucleus, of which nothing 

 more is revealed to us in the development of the roots of Chara, 

 than that, so long' as new cells are to be budded forth from the 

 one to which the nucleus belongs, the nucleus continues in active 

 operation, but when this ceases it becomes effete ; while the rota- 

 tion of the protoplasm and subsequent enlargement of the cell, 

 &c., which are much better exemplified in the plant-stem than in 

 the root-cell, go on after the nucleus ceases to exist. Hence 

 the development of the root-cells of Chara affords us nothing 

 positive respecting the functions of this organ ; and, therefore, 

 if we wish to assign to it any uses in particulai*, they must be 

 derived from analogy with some other organism in which there 

 is a similar nucleus whose office is known. Now, if for this 

 purpose we may be allowed to compare the nucleus of Chara 

 with that of the Rhizopodous cell which inhabits its protoplasm, 

 we shall find the two identical in elementary composition ; that 

 is, both consist at first of a " nuclear utricle,^' respectively 

 enclosing a structureless, homogeneous nucleolus ; the latter, 

 too, in both, is endowed with a low degree of movement. After 

 this, however, the nucleolus of the Rhizopod cell becomes granular 

 and opake ; and, when, under circumstances favourable for pro- 

 pagation, a new cell-wall is formed around the nuclear utricle, — 

 or this may be an enlargement of the nuclear utricle itself, — I do 

 not know which ; the granular substance of the nucleolus becomes 

 circumscribed, and shows that it is surrounded by a spherical, 

 capsular cell ; the granules enlarge, separate, pass through the 

 spherical capsule into the cavity of the "nuclear utricle;" a 

 mass of protoplasm makes its appearance, and this divides up 

 into monads, or, as I first called them, "gonidia*." The 

 nucleolus of Chara, on the other hand, after having provided the 

 two cells developed from its own root-cell, becomes stationary, and 

 also divides up into a number of small, round, graniform nucleoli, 

 which disappear in some way or other unknown to me, leaving 

 the nuclear utricle, at least, effete. Whether these small nucleoli 

 are ultimately dissolved, or find their way into the rotating pro- 

 toplasm, I am, as I have before stated, ignorant ; but, so far as 

 this multiple division goes, we have an analogous termination 

 between the nuclei of these two organisms; and when we re- 

 member that the nucleus of the cell in which the globule of 

 Chara originates, must furnish all the cells with nuclei which 

 bear respectively the antherozoids, — that these nuclei are very 

 * Anu. and Mag. Nat, Hist. vol. xvii. p. 101, 1856. 



