30 



GENUS PALLAVICINIA 



The Embryo 



The only account of the development of the sporophyte in the genus 

 Pallavicinia that we have been able to find is that of P. decipiens. In this 

 species Farmer [i] gives a brief description and figures of early stages 

 of the embryo, which seems to differ a good deal from that of P. Zollin- 

 geri and P. radiculosa, and to more nearly resemble that of Morkia hiber- 

 nica. (See Leitgeb [i], Pt. Ill, PL vi.) 



While the sections of the embryos that were obtained were more or 

 less badly shrunken, still the most important points in their development 

 could be made out pretty well. Most of the younger stages found were 

 of P. Zollingeri, but a few were also found in P. radiculosa and P. Levieri 

 which agreed closely with the former species. 



The youngest specimen that was examined consisted of two nearly 

 equal cells, separated by a transverse wall (Fig. 16, A). The next divi- 

 sion probably is also transverse, and arises in the upper cell, dividing the 

 embryo into three superimposed cells, as is the case in P. decipiens. In 

 the next older stage that was found, the embryo showed two large basal 



Fig. 16. Pallavicinia Zollingeri. 



A. Two-celled embryo, enclosed in calyptra, x 200. 



B. An older embryo. 



C. D. Older embryos, x about 50. 



E. Upper part of D, more highly magnified. 



