738 THE AMERICAN NATURALIST. [VOL. XXXVIII. 



have been Lawson ('98) on Cobea, W. C. Stevens ('98^) on 

 Asclepias, Atkinson ('99) on Arisaema and Trillium, Duggar 

 ('99) on Bignonia, Wiegand ('99) on Convallaria and Potamoge- 

 ton, Gregoire ('99) on Lilium and Fritillaria, Guignard ('99) on 

 Naias, Williams ('99) on Passiflora, Duggar (: oo) on Symplo- 

 carpus and Peltandra, Lawson (: oo) on Gladiolus, Byxbee (: oo) 

 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 completeness 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 

 named perikaryoplasm. This zone developed a felted envelope 

 of fibrillse from which projections extended to form the cones of 

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

 oped the bipolar spindles. The spindle fibers of Gladiolus are 

 formed entirely from the perikaryoplasm, the nucleolus and linin 

 apparently taking no part in the development of the spindle. 

 The nucleolus remains intact 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. The 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 in Lavatera, described by Byxbee (: oo), than 1 in Passiflora. 

 It forms in Lavatera a dense zone that suggests a gathering of 

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

 felt around the nuclear membrane and enter the nuclear cavity 



