730 THE AMERICAN NATURALIST. [VoL. XXXVIII. 



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



FIG. 12. Spore mother-cells of Hepatic.-e. a, 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. 

 b, metaphase of the first mitosis ; the spindle in all respects a normal bipolar structure 

 without centrospheres. c, Metaphase 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, d, anaphase of the second mitosis: one spindle viewed from the side, the 

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

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

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

 out centrospheres. g t metaphase of second mitosis; very small spindle, h, cell p.ate 

 forming in the spindle between two nuclei, z", 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 other regions of the cell, (a, 

 b, c, d, after Moore, :os ; h, i, after Van Hook, : oo.) 



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- 



