356 BOTANICAL GAZETTE. 
a large number of healthy young prothallia was the result. En- 
couraged by this success, O. sensibilis was tried with similar 
results. Lack of time prevented following out the complete de- 
no sexual organs were developed upon them. Other cultures 
pre Made upon rotten wood, upon which they are frequently 
found naturally, an upon porous pottery, but in neither case 
was the result as good as when grown upon damp earth. In 
order to maintain an even degree of moisture, it was found best 
to the air. Excess of moisture, especially after the prothallia are 
at all advanced, must be guarded against, as they will decay if 
and be kept damp, but not muddy. 
Spores may be started at any time, but the best results are 0 
tained by sowing in warm weather, or at least when they can be 
kept at a tolerably uniform temperature. In winter, even with 
artificial heat, growth almost ceases, the deficient light seeming 
to affect them unfavorably, as well as the lower temperature. 
Probably in a green-house, where the fluctuations of temperature 
are less marked, this would be less apparent. 
By following the directions given, no trouble should be ex- 
perienced in growing any of our common fern 
spore adhered so firmly to the spore as to make it impossible te 
determine whether this third coat was present or not. 
