1901] SPORANGIA AND GAMETOPHYTES OF SELAGINELLA 173 
The diaphragm which Pfeffer thought was the wall of the first 
division of the spore Heinsen regards as the plane of separation 
between the small cells at the apex of the gametophyte and the 
larger ones below, and not a wall. He also refutes Pfeffer’s state- 
ment that ultimately the cell divisions completely occupy the 
basal region of the spore. Heinsen lays great stress on the 
supposed fact that the nuclei of the Selaginellaceae increase 
solely by direct division. He investigated material killed at all 
hours of the day and night, not only spores but vegetative tips, 
with special reference to establishing this point. He found a 
total absence of karyokinetic figures. As this statement, which 
if true would be most surprising, has not been refuted by later 
writers, it may be of interest to note a possible explanation of 
the error. In describing his methods of imbedding, Heinsen 
says that he killed his material by immersing some specimens for 
ten minutes in Flemming’s fluid, others three minutes in aI 
per cent. corrosive sublimate solution, still others ‘mit gleich 
gutem Erfolge wante ich ein zweimaliges schnelles Eintauchen in 
kochendes Wasser an.” It is doubtful whether any of the kill- 
ing fluids thus employed had opportunity to penetrate the 
sporangium wall in so brief a contact; in which case his mate- 
rial died a lingering death through the washing and dehydrating 
processes. Under such conditions naturally there would be no 
traces of karyokinesis. The statement that he had as good 
results from two quick dips in boiling water as from the Flem- 
ming fluid is otherwise inexplicable. It is somewhat difficult to 
determine whether Heinsen means his statements to be general 
with regard to all the species he enumerates or not. His sum- 
mary leads one to assume that the sequence of events there set 
down is true of the eleven species above named. There are cer- 
tainly inaccuracies in many details if applied to S. apus. 
Arnoldi in the Botanische Zeitung of 1896 followed in a brief 
article on “Die Entwickelung des weiblichen Vorkeimes bei den 
heterosporen Lycopodiaceen.”’ He investigated S. cuspidata elon- 
ata, and gives a résumé of Heinsen’s paper, He agrees with 
Heinsen on all points, thus reiterating the misinterpretation of 
| 
