BOT— Vol. I.] LAWSON—COBMA SCANDENS. 



179 



In all other cases where multipolar spindles have been 

 observed the earlier stages have not been sufficiently inves- 

 tigated to warrant any statement as to whether they follow 

 the Equisetum type or that here described for Cobcea. 



From the series of stages here figured the writer can 

 only conclude that centrosomes or directive spheres can 

 take no part in the formation of the spindle, and they con- 

 firm the idea that has already been expressed that in the 

 vascular plants the method of spindle-formation is entirely 

 different from that which prevails in the lower plants and 

 animals. 



In conclusion I wish to acknowledge my indebtedness to 

 Mr. Osterhout for many valuable suggestions in the prep- 

 aration of this paper. 



SUMMARY. 



The observations made upon the formation of the spindle 

 in Cobcea may be briefly stated as follows : 



A granular substance gradually accumulates and forms a 

 complete zone around the nucleus. This zone is designated 

 perikaryoplasm. Upon the breaking down of the nuclear 

 wall the linin of the nucleus and the perikaryoplasm form a 

 network which occupies the central portion of the cell. 



This network grows out into several projections which 

 become the cones in the multipolar figures. 



The spindle-fibres are formed by the elongation of the 

 meshes of the network in the direction of the projections. 



The cones elongate and become sharply pointed. They 

 fuse in two groups and form the bipolar spindle in the same 

 manner as that observed by Osterhout in Equisetum. 



The mature spindle is characterized by the great length 

 and crossing of the mantle-fibres. 



The spindle-formation of the second division is identical 

 with that of the first division. 



No bodies that could be identified as centrosomes were 

 found in any stage of the process. 



Botanical Laboratory, 



University of California, 



April, 1898. 



