METHODS 



31 



cells, forming a sort of suspensor, and a terminal portion, consisting of 

 four tiers of cells, from which all of the sporogonium except the sus- 

 pensor is derived (Fig. 16, B). It is probable that two of the three pri- 

 mary cells of the embryo contribute to the suspensor, while all the rest 

 of the sporophyte — foot, seta and capsule — is derived from the terminal 

 cell. This, however, was not positively demonstrated. 



Fig. 17. 



A. Longitudinal section of an embryo of P allavicinia radiculosa, x 300. 



B, C. Cross-sections of embryos of about the same age, of P. Levieri. The embryo 



shown in B was cut somewhat obliquely. 



The lower suspensor cell does not undergo any further division, but 

 the upper one may divide two or three times, and there results an ex- 

 tremely conspicuous haustorial organ of the same character as that ob- 

 served in various Jungermanniales, both acrogynous forms like Junger- 

 mannia bicuspidata and anacrogynous types like Aneura. (See Leitgeb 

 [1], Clapp [1].) 



Material was wanting for the next stages of development, but to 

 judge from such stages as those shown in Fig. 16, C-E, the first division 

 in the terminal cell of the embryo is vertical, and this is followed later by 

 a series of transverse divisions. There is, however, a certain degree of 

 irregularity in the divisions, as there is considerable variation in the ar- 

 rangement of the cells in different embryos. 



The upper part of the embryo rapidly elongates, and forms a nearly 

 cylindrical body, the apex of which is slightly enlarged, and marks the 



