1901 | SPORANGIA AND GAMETOPHYTES OF SELAGINELLA 139 
they go (figs. roS-r20). Avery close series of stages from start 
to finish is necessary to produce confidence in any interpretation 
of phases of a plant which displays so many irregularities, and 
evidently has so nearly lost its power of sexual reproduction. 
The development of the microspores has not yet been fol- 
lowed in detail. Observations on this subject, together with the 
growth of the female gametophyte and the embryology, will be 
given in a future paper. One interesting feature that may be 
noted now is the incomplete septum which projects into the 
cavity of the microsporangium (fig. 725). This is formed in 
part from sterilized sporogenous tissue and in part from the 
cells of the pedicel. 
Since the above was written, a package of fresh material has 
been sent me from Texas. All the plants have begun their 
spring growth and the winter strobili are growing at the apex. 
The first sporophylls of the season subtend megasporangia. I 
find not more than eight or ten in each strobilus. Above these 
are microsporangia to the number of twenty or thirty. In this 
material it has been my good fortune to observe the method by 
which the spermatozoids obtain their entrance to the megaspo- 
rangia. A perfectly fresh, vigorous strobilus was cut from the 
plant and stripped of its sporophylls, thus exposing the sporan- 
gia zm situ. A megasporangium, which was observed gaping 
open and in close proximity to a microsporangium that had 
discharged its microspores, was separated from the strobilus and 
examined under the microscope. Six microspores were caught 
on the sculptured surface of the megasporangium near the edge 
of the valves, which were slightly separated from each other. 
One microspore, evidently mature from the fact that the exospore 
was split and the endospore protruding, suddenly discharged a 
current of slime which at first proceeded directly away from the 
megasporangium. Soon, however, as if acted upon by some 
attractive influence from the gametophytes within, the stream 
turned abruptly and entered the opening between the megaspo- 
rangium valves. The spermatozoids were swimming with char- 
acteristic rotary motion in this stream. With difficulty, it was 
