280 Evans: HEPATICAE OF PUERTO RIvO 
of on the margin. In consequence of this position the stalk cell 
becomes displaced, as it were, from the margin to the surface of 
the gemma but is always eccentrically attached. Since the gem- 
mae in Cololejeunea are essentially like those in Leptocolea and 
A phanolejeunea, the three genera will be considered together. 
In some species gemmae are very abundantly produced, while in 
others they are much more sparingly developed. It is probable 
in fact that certain species are never gemmiparous, but it would 
be premature to make a statement to this effect about many indi- 
vidual species at the present time. The production of gemmae is 
not accompanied by any striking modifications in leaf structure 
or by any marked limitation of growth. 
The structure and development of the gemmae have been 
described more or less fully by Goebel in Leptocolea Goebelii,* by 
Stephani in Leptocolea cuneifolia (Steph.) comb. nov.,t by Cavers 
in Cololejeunea calcarea,t and by Stevens in C. Biddlecomiae.§ 
Stevens showed that the gemmae of C. Biddlecomiae and C. cal- 
carea pursued essentially the same course of development as that 
described by Goebel for the gemmae of L. Goebelii and explained the 
slight discrepancies to be found in Cavers’s account of C. calcarea. 
The writer has been able to study the gemmae in five species of 
Cololejeunea, nine of Leptocolea, and two of A phanolejeunea and 
finds that all agree closely in their development with the species 
discussed by Stevens. According to his account the leaf cell 
which is to form a gemma projects beyond its neighbors and 
divides by a wall parallel with the surface of the leaf. The outer 
cell represents the mother cell of the gemma, while the inner cell 
becomes the stalk. The mother cell then proceeds to divide by a 
series of walls perpendicular to the leaf surface, and the resulting 
gemma consists in consequence of a plate of cells one cell thick. 
The first wall divides the mother cell into two semicircular cells, 
and the subsequent divisions which take place in these cells are the 
same, thus making the mature gemma symmetrical with respect 
to the median plane. The two semicircular cells are first divided 
* Ann. Jard. Buitenzorg 7: 240. 887. ee 
+ = Lejeunea (Cololejeunea) cuneifolia Steph. Hedwigia 30: 167. pl. ro. 
1892. 
' t New Phytol. 2: 160. J. 8. 1003. 
§ Bull. Torrey Club 37: 366-369. f. 1. 1910. 
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