1901] SPORANGIA AND GAMETOPAYTES OF SELAGINELLA apt 
spore. The upper layers of cells are much smaller and irregu- 
larly polyhedral in shape. No diaphragm is formed. Three 
tufts of trichomes grow from the upper surface of the prothal- 
lium, rend the exospore into three flaps along the ridges at the 
apex, and push them up out of the way of the developing 
archegonia. Only a limited number of the latter develop, some 
five to ten as compared with Pfeffer’s report of thirty in S. 
Martensii. There are four rows of neck cells, with three cells in 
each row. Pfeffer reports but two cells in each of the four rows 
in S. Martensii; Campbell reports two in S. Kraussiana. Heinsen 
gives a list of eleven species: S. Martensii, S. lepidophylla, S 
Willdenoviana, S. denticulata, S. apus, S. erythropus, S. Helvetica, S. 
serpens, S. Douglasi, S. glauca, S. pilifera, and says that he agrees 
with Pfeffer on this point. Bruchmann finds that although sev- 
eral embryos may start to grow, but one comes to maturity. 
The first division of the oospore of S. spinulosa is transverse to 
the axis of the archegonium, and the cell nearer the neck 
becomes a suspensor. . 
The most notable fact, however, is that this embryo has no | 
: foot. ‘Ein Fuss in dem Sinne, sie ihn z. B. S. Martensii, S. 
Apo Kraussiana und andere Arten besitzen, fehlt.” Whereas, the 
ryo of S. apus; as 1 have found, has (no suspensor, After 
tupesives ete perme the cover cells of the archegonium close together, 
ov cfenozs the walls of the neck cells thicken and turn brown. On the 
other hand, Pfeffer maintains that the neck of the archego- 
nium of S. Martensii gapes widely during the entire embryonic 
development; and he represents the suspensor pushing up into 
the neck canal like a wedge. This latter method is the rule 
in most pteridophytes, and hence S. spinulosa together with S7 
apus-and S. rupestris are exceptions. 
In the last twenty years, as far as I know, but four other con- 
tributions have been made to a knowledge of these phases of 
the history of the Selaginellas. In 1871, Pfeffer published his 
paper ‘Die Entwickelung des Keimes der Gattung Selaginella.”’ 
The extreme difficulty of interpreting the spore and prothallial 
Structures, even with the aid of all the modern technique, makes 
