456 The Botanical Gazette. [November, 
The actual length of the spindle from pole to pole was greater 
than the length of the cell. It appeared as though there was 
not enough room for the division of the nucleus, and the 
bodies had wandered to the corners in order to gain more 
space for the formation of the spindle. It seems to me that 
this phenomenon explains itself if we admit that the attrac- 
tion-spheres are directive in their function, and control 
nuclear division; but the appearance might be just as well 
accounted for by supposing that the controlling power rested 
in the nucleus or the cytoplasm of the cell in general. 
Results. 
The special results of the investigation are as follows: 
I. Centrosomes aud attraction-spheres are present in non- 
reproductive as well as reproductive vegetable cells. 
2. They remain on the outside of the nucleus during its 
resting stage. 
3. They persist in cells which have ended their growth 
and division. : 
Besides the foregoing results, the present investigation 
furnishes confirmation to the following propositions: 
I. In phanerogams there are two of these bodies for each 
resting nucleus. : ; 
2. When the nucleus begins to divide, one or both of the 
bodies migrate so as to take their positions at the poles of 
the future spindle. 
3. Subsequently they immediately begin to divide, the 
division being completed in the prophase of the mother nu- 
cleus. ; 
4. After-their migration, the attraction-spheres remain at 
the poles of the nuclear spindle, and do not change their post- 
tion until the beginning of the following division. _ 
5. They seem to be organs which institute and direct nu- 
clear division. 
Summary. 
The theory advanced by Van Beneden has received the pt 
port of many of the leading biologists, and has with some a¢- 
ditions been quite generally substantiated by investigations. 
Taking the facts and opinions of those who have studied these 
bodies, into general consideration, the subject seems to be Hn 
the following condition: There is a permanent body in t 
