99 
The Nucleus and Heredity. 
to the view that the nuclei of this group are not all comparable 
with one another; we have, in Hartmann’s terminology, monoenergid 
and polyenergid nuclei, and we have mitoses of different nature. 
Again there is the hypothesis of the “dual” nature of the nuclei, 
which applies especially to the Flagellata, one part of the nucleus 
being concerned chiefly with the motor activities of the cell and the 
other being of ordinary, so-called idiochromatic, nature. 1 Also it 
appears possible that in many cases a protozoan nucleus is 
comparable not with the whole nuclei of higher organisms but 
merely with a single chromosome of such a nucleus. From such a 
point of view what appears to be a simple, direct nuclear division in 
a protozoon may be quite as efficient a process of equal division as 
that of the splitting of a chromosome of a nucleus of one of the 
higher forms. Then again there is the possibility that the material 
particles representing the simpler hereditary equipment of the 
lower forms may be many times repeated, 2 so that a less complex 
method of separation than that of mitosis with chromosome splitting 
may be sufficient to safeguard, during division, the equality of the 
hereditary equipment handed on to the new cells. 
Some workers on the evidence of the occurrence of amitosis 
and the behaviour of the Protozoa have been inclined to give up the 
theory of the importance of the chromosomes and even that of 
nuclear idioplasm. This does not seem, however, a judicial position 
to take up on consideration of the balance of evidence from the two 
sides. On the one hand we have the evidence, of rather a doubtful 
nature, of amitoses in higher forms; and the evidence of amitoses 
in lower forms, which is rather difficult of interpretation. On the 
other hand there is the large amount of circumstantial evidence 
already detailed, the important experimental evidence of Godlewski, 
Herbst and Boveri, and the striking evidence from some of the 
Angiosperms. On the whole it must be admitted that, for the 
higher organisms at least, the theory of nuclear monopoly in the 
transmission of hereditary properties still holds the field, and is the 
theory which most fully explains the majority of facts. In the case 
of some Angiosperms the absence of the male cell-protoplasm may 
fairly be considered as direct proof of this monopoly. 
1 In the blood-parasite, Hamoproteus noctiuB, for example, the 
sexually produced individual has a single nucleus which soon 
divides into two ,one an ordinary nucleus, the other, (the so- 
called blepharoplast) connected with the flagellum. On cell 
division both these nuclei can divide mitotically. 
1 This may explain the fact that the cell and nucleus of such a 
form as Stenlor may be divided and each of the parts will 
grow into a complete individual. 
