Box.— Vol. I.] WILLIAMS— PASSIFLOR A CCERULEA. 1 95 



cases. Osterhout (1897) describes it for the spore-mother- 

 cell of Equisctum as follows: The process begins by the 

 meshes of the reticulum immediately surrounding the nu- 

 cleus becoming drawn out parallel to the nuclear wall 

 and forming a sort of skein about it. This condition is 

 transitory; soon the cytoplasm immediately surrounding 

 the nucleus does not consist of a network, but of radially 

 arranged fibers which gradually grow longer and push 

 out into the surrounding cytoplasm. At first these cross 

 each other in all directions but soon become parallel. 

 Later, they bend toward each other and form numerous 

 cones which begin to fuse, the nuclear membrane, mean- 

 while, disappearing in places. The threads of the cones 

 penetrate into the nucleus and come into connection with 

 the linin threads. The nuclear wall entirely disappears and 

 the multipolar spindle is formed. Mottier (i897«) describes 

 a similar origin of the multipolar spindle. The following is 

 a summary of Belajeff's account of its origin in the pollen- 

 mother-cell of Larix : The cytoplasm immediately sur- 

 rounding the nucleus takes on an arrangement which, at 

 first glance, produces the impression of a skein-like mass 

 of threads wound around the nucleus, forming a distinct 

 zone. It really consists of a network, the meshes of which 

 are drawn out parallel to the nuclear wall. (In this, Stras- 

 burger's work on Larix agrees with Belajeff's). The 

 nucleus soon becomes filled with a linin network. The 

 nuclear wall disappears entirely and the inner linin network 

 and the outer cytoplasmic one unite to form a continuous 

 reticulum. Fibers pass from the " Centralkorper " (as 

 Belajeff calls the central network) to the cell-wall, running 

 radially or tangentially through the cell. The fibers, by 

 their contraction, pull the " Centralkorper " out into a 

 three- or four-angled body. Several fibers unite in a pole 

 which is situated toward the periphery of the cell and is 

 connected by fibers with the cell-wall, as well as with other 

 poles. The chromosomes lie in the middle of the *' Central- 

 korper," surrounded and held in place by a network whose 

 fibers are gradually drawn out to form the spindle-fibers. 



