572 BULLETIN OF THE 



in texture exactly like that which surrounds the vesicle and stretches out 

 between the globules of " protolecith." " These masses protrude slightly into the 

 cavity of the germinative vesicle, which otherwise remains perfectly rounded" * 

 This internal limitation is therefore very easy to distinguish, but externally they 

 are absolutely indistinguishable from the vitelline sarcode of which they form 

 a part. From these masses striae soon arise which take the direction of me- 

 ridional lines. These become more distinct, and are changed into [?] veritable 

 filaments. Falling short of the equatorial plane, they do not yet encounter 

 each other. During all the phases of their formation, the peripheral extremities 

 of these filaments are in continuity with the protoplasmic network which occupies 

 the interior of the nucleus. As the rays advance, the network disappears. It is 

 more than probable that the rays are only a modification of the form of the 

 intranuclear network, and that they result from a regular arrangement of 

 its trabeculoe. This view of the origin of the spindle fibres is not directly 

 reconcilable with the one I have expressed ; nevertheless, I see no occasion 

 to modify the argument based on the great distance which in Limax inter- 

 venes between the nucleus and the centres of the asters. The account of the 

 origin of the polar masses I will give in the words of the author. 



" Quant aux amas polaires, leur origine premiere est bien plus difiicile h etablir. 

 J'avoue que, pour ma part, je n'y suis pas parvenu et qu'a cet egard je ne puis 

 que poser une alternative sans la resoudre. Ces amas peuvent provenir du 

 sarcode intranucleaire qui se porterait aux deux poles opposes du noyau et se 

 confondrait avec le protoplasme vitellin,.ou bien ils peuvent provenir du proto- 

 plasme perinucleaire qui ferait irruption dans la cavite de la vesicule ; a moins 

 encore que ces deux processus ne se produisent simultanement, et qu'il n'y ait, 

 des le premier instant, une fusion entre ces deux substances. Que cette fusion 

 soit immediate ou non, il est incontestable que les protoplasmes intra- et peri- 

 nucleaire ne tardent pas a se confondre aux deux poles, en sorte que, un peu 

 plus tot, un peu plus tard, il y a toujours fusion. 



" Les amas polaires faisaient d'abord une legere saillie dans Tinterieur de la 

 vesicule spherique. Pendant la croissance des rayons intranucleaires, ils s'eloi- 

 gnent du centre et font de part et d'autre hernie dans le vitellus. II en resulte 

 que la vesicule passe de la forme spherique a celle d'un citron tres-court. Pen- 

 dant ce temps les rayons nucleaires, qui se trouvent pres de I'axe qui rejoint les 

 deux poles, sont arrives k se rencontrer et se sont sondes de maniere a consti- 

 tuer quelques filaments bipolaires ; les rayons lateraux de chaque aster vont 

 encore se perdre dans le reseau intranucleaire." 



The extranuclear rays arise at the same time as the intranuclear, and the 

 growth of both is exactly alike. There is therefore a time during which each 

 centre of attraction is surrounded by a system of rays without being yet joined 

 to that of the neighboring aster. The amphiaster occupies at first an eccen- 

 tric position. The small grains representing the nucleolus may possibly go 

 directly to the spindle, since granules of entirely similar appearance are seen 

 along the intranuclear rays when the amphiaster is still incomplete. The 



* Not italicized in the original. 



