730 THE AMERICAN NATURALIST. [Vol. XXXVIIl. 



are not different in any essentials from those of other plants.. 



Fig. 12. — Spore mother-cells of Hepaticze. «, b, c, d, Pallavicinia lyellii. a. Prophase ; the 

 fibrillae gathered on four sides of the nucleus which has a tetrahedral form pointing into 

 the four lobes of the spore mother-cell; the nuclear membrane has not yet broken down; 

 similar stages of prophase were probably considered by Farmer as quadripolar spindles. 

 bi metapbase of the first mitosis; the spindle in all respects a normal bipolar structure 

 without centres pheres. c, Metapbase of the second mitosis; one spindle shown in side 

 view, the other, almost perpendicular to the first, presents the eight chromosomes at the 

 nuclear plate, rf, anaph'ase of the second mitosis; one spindle viewed from the side, the 

 other from one end shows the group of eight grand-daughter chromosomes. e,y", g, antho- 

 ceros laevis, k, i, a larger species from Italy, e, prophase; one pole of spindle developed. 

 f, just after metapbase of the first mitosis ; eight chromosomes ; blunt poled spindle with- 

 out cent rosphe res. g^ metapbase of second mitosis; very small spindle. A, cell p-ate 

 forming in the spindle between two nuclei. /, two nuclei at the side of their respective 

 chromatophores and the cell plate between, after the second mitosis ; a third chromato- 

 phore shown with strands of protoplasm connecting it with otlier regions of the cell, (a, 

 ^, c, d, after Moore, : 03 ; h, i, after Van Hook, ; 00.) 



The " quadripolar spindle " proves to be nothing more than a 

 condition of prophase. 



Besides Pellia and Pallavicinia, which are the most thoroughly 

 studied of the lower liverworts, we know the processes of sporo- 



