V. H. Blackman. 
98 
in these observations against the view of the monopoly of the 
nucleus in the transmission of hereditary properties, a monopoly 
which certainly exists in Lilium where, as mentioned earlier, the 
fertilising element is not a cell but a naked nucleus. 
When we come to consider the relation of amitosis to the 
hypothesis of nuclear idioplasm we are on much more difficult ground. 
The simple method of amitosis (in which the nucleus becomes 
drawn apart into two portions without any elaborate process of 
chromatin division) has been known for a long time, but until 
recently it has usually been held that amitosis was only to be found 
in cells which will soon degenerate, or at least was absent from cells 
in the direct line of the reproductive cells. Child and some other 
workers have described amitotic divisions in various tissues among 
the higher animals, even in connexion with the formation of the 
sexual cells, but the evidence brought forward has been sharply 
criticized and does not appear conclusive. Nuclear fusions are 
easily confused with amitotic divisions, and in order to prove that 
the nuclei produced amitotically are normal ones it is necessary 
that they should be followed later into an ordinary mitotic division 
which shows the normal number of chromosomes. 
Among the lower plants the experiments of Nathansohn are 
the most conclusive. He treated Spirogyra filaments with a dilute 
solution of ether ,with the results that the nuclei divided amitotically. 
The cells so produced were isolated and grown under normal 
conditions, when they divided mitotically in a normal way. In the 
case of the lower fungi amitosis occurs without much doubt in such 
cases as Synchytrimn, 1 Spongospora , 2 and Plasniodiophorap and it 
seems also to occur in the Uredineas. 4 
In the Protozoa also, direct amitotic division is frequently met 
with, though many forms show well-marked indirect (mitotic) 
division. Also in this group we meet with the fact that a fragment 
of a cell which contains only a portion of the nucleus may 
regenerate a complete new cell, as in the case of Stentor. 
As to the relation of these facts of amitosis to the general 
theory of nuclear idioplasm it is impossible to say at present how 
much weight should be placed on evidence drawn from the lower 
forms of life. The question of the nature of the nuclei of the 
Protozoa is one of considerable complexity. One need only refer 
1 R. F. Griggs, Bot. Gaz. 47, 1909, p. 125. 
2 F. T. B. Osborn, Annals of Botany, XXV, 1911, p. 27. 
3 Prowazek, Arbeit, a. d. kais. Gesundheitsamte, XXII, p. 396. 
4 Blackman, Annals of Botany, 1894 ; British Association, 
Sheffield, 1910. 
