THE AMRRICAX XAIT RA IJST. [\\n.. XXXVIII. 



(•99) Im Bi^nonia. WicM^uul ('99; on ( mvallaria and Potamo^e- 

 ton, (irc-oiR" (•99) on Lilium and iMitillaria. (iuio-nard ('99) on 

 Naias, Williams ("99) on Passiflora. Du-'-ar (: 00) on Symplo- 

 carpus and Pcltandra, Lawson (:oo) on (iladiohis, Hyxbee (: 00) 

 on Lavatera, Andrews (: 01) on Magnolia and Liriodendron, 

 Schniewind-Thies (:oi) on Galtonia and Osterhout (:02) on 

 Agave. 



Of the papers listed above several demand especial attention 

 for the conij)leteness of the studies on the early stages of spindle 

 formation in the pollen mother-cell. Lawson ('98 and :oo) 

 found that the nuclei of Cobea and (Gladiolus previous to mitosis 

 were surrounded by a zone of granular kinoplasm which he 

 perikaryoplasm. This zone developed a felted envelope 



fibrillre 



projec 



a multipolar figure. The cones by fusing in two groups devel- 

 oped the bipolar spindles. 'Phe spindle tillers of (iladiolus are 

 formed entirely fr<^m the jjerikaryoplasm, the nucleolus and linin 

 apparently taking no part in the development of the spindle. 

 The nucleolus remains ijitact until after the dissolution of the 

 nuclear membrane when the spindle is practically completely 

 organized. Miss Williams ('99) found for Passiflora that the 

 nuclear cavity became filled with a network developed from the 

 linin. l"he nuclear wall became also transformed into a mesh 

 which connected the network from the linin with the surround-' 

 ing cytoplasmic reticulum, thus forming a continuous system 

 throughout the cell. The central region of this network, 

 enclosed by a granular zone, developed a multipolar figure 

 whose poles finally fused to form a bipolar spindle. The con- 

 trast between this type of spindle in which so much of the 

 fibrous structure is derived from the linin and that of (Gladiolus 

 just described is very marked. A granular region outside of 

 the fibrous network around the nucleus is much more conspic- 

 uous m laxatera, described by Byxbee (:oo), than in Passiflora. 

 It torms m I>a\atera a den.se zone that suggests a gathering of 

 nutritive material (deutoplasm). The fibrilkc are developed as a 

 felt around the nuclear membrane and enter the nuclear cavity 



