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



never unite^ and therefore watched for the time of their provi- 

 sioning the third root-cell ; when at the end of the fifth hour 

 union commenced, and an hour afterwards was complete. Twelve 

 hours after, this nucleolus also disappeared; and about an hour 

 and a half from this time, the oblique septum dividing the second 

 from the third root-cell was just visible, with the parent nucleus 

 and its counterpart on each side of it respectively. Can the 

 conjugation of the nucleoli, if it may be so termed, have anything 

 to do with the reproduction or restoration of the size of the 

 nucleus, as in some species of Spirogyra and Diatomea, where 

 the contents of two cells, which have been derived from an in- 

 terseptal division of one, unite again to form the spore ? The 

 same kind of quadruplication of the nucleolus appears to take 

 place in the formation of the plant- cell of Char a, judging from 

 two instances which occurred to me; and in looking for this 

 generally it may be remembered that, whenever double nucleoli 

 are seen in the nuclear utricle of Chara, it is a sure sign of this 

 process having taken place, for even if the parent nucleus is ever 

 in such a condition, it is at that time invisible. 



On one occasion I found two nuclei with their two nucleoli 

 respectively still disunited, in the axial fluid of the rotating pro- 

 toplasm, while each nucleus was reduced to a clear transparent 

 oblong cell; and on looking for the primary nucleus in its 

 natural position, as well as for the nucleus of the rootlet-cell, 

 the projection for which was already somewhat advanced, I found 

 that they were both absent, while the presence of vacuoles in the 

 protoplasm filling the projection for the rootlet-cell, which was 

 not yet cut ofi" from the parent, showed not only that this proto- 

 plasm was undergoing solution, but, also, that the development 

 of the rootlet-cell had been arrested. No doubt, therefore, re- 

 mained in my mind that the two nuclei in the axial fluid were 

 the primary nucleus and the nucleus of the rootlet-cell. In these 

 instances the nucleoli were clearly seen, and they presented the 

 form of spheres filled or lined with a semi-opake, homogeneous, 

 yellowish substance, in the centre of which, on the surface of 

 each, was a circular hyaline area or vacuole. In the nucleus 

 nearest the free end of the root-cell, whose nucleoli were 

 separated for some distance from each other (fig. 11), a trans- 

 parent cell round each nucleolus could be perceived (a, a), but 

 this was not apparent in the nucleus which was furthest from 

 the end of the root-cell, whose nucleoli were in contact. The 

 position of these nuclei, away from their proper situations, does 

 not seem inexplicable, when we remember the migrating power 

 of this organ, the want of a septum to keep the nucleus of the 

 root- cell in its place, and the vacuolar solution that the fixed 

 protoplasQi was undergoing in which they ought to have been 



