78 KANSAS UNIVERSITY QUARTERLY. 
the reception and transmission of stimuli. The fact that it is nec- 
essary for the nuclear membrane to be dissolved away during 
mitosis is evidence of its efficiency in demarking the nucleus as a 
distinct organ of the cell. It is, therefore, not necessary in ac- 
counting for the action of the nuclear membrane during nuclear 
division to anticipate for it any special function at this time, and it 
is highly probable that it undergoes only enough change to render 
it soluble, and that the substance of it 1s put to immediate use in 
the formation of the membranes of the daughter nuclei. It is pos- 
sible, however, that the substance of it may take part in the for- 
mation of the spindle! and later enter into the construction of the 
membrane of the daughter nuclei. 
The nuclear framework, from which the nuclear thread and the 
chromosomes successively arise, is unquestionably that part of the 
nucleus upon which the important duty of bearing the inheritable 
qualities specifically devolves. This is shown by the extreme ex- 
actitude with which the substance of the nuclear thread is divided 
in the formation and division of the chromosomes. 
The character and behavior of the nucleolus do not make its 
function so evident as the functions of the nuclear thread and 
membrane appear. Although the nucleolus is a structure which is 
very rarely absent in the resting nucleus there is no evidence that 
it has a function to perform at such a time other than possibly the 
nutritive one of contributing to the formation of cell walls and 
starch grains. ” 
The conception is a fairly well grounded one that the nucleolus 
is reserve material to be used in the formation of new structures 
which arise during mitotic cell division. If this is a fact the pres- 
ervation of the nucleolus within the nuclear membrane points to the 
nucleolus as a substance of great importance for the processes of 
mitosis, requiring the resting nucleus for its formation, and therefore 
not capable of being provided after nuclear division begins. The 
major part of the evidence taken from plants seems to show that 
the nucleolus is a stimulant and nourishment in the formation of 
the kinoplasm. Strasburger gives the following data for this 
conclusion: The enclosure of the nucleoli in the daughter nuclei 
after cell division appears to result in a diminution of the kino- 
plasm. The formation of the kinoplasmic spindle and the solution 
of the nucleolus occur simultaneously. After the solution of the 
nucleolus that portion of its substance which is not used in the 
1 Flemming, Neue Beitraege zur Kentniss der Zelle. If Teil. (Arch. f. mikr. Anat. 
Bd. 37, p. 685.) s ! 
2 Strasburger, Ueber Kern und Zelltheilung im Pflanzenreiche, pp. 195-200. 
