264 
METHODS IN PLANT HISTOLOGY 
For the development of the antheridium and sperm, and especially 
for the blepharoplasts and their transformation, cut about 3 y in 
thickness and use iron-haematoxylin; for the development of arche- 
gonia, cut at 5 y and stain in the safranin, gentian-violet, orange 
combination. 
The gametophyte of Botrychium is subterranean and tuberous. 
It sometimes reaches a length of 7 to 12 mm. and a thickness of 4 to 
5 mm. Usually, it is not more than 5 or 6 mm. long and 2 or 3 mm. 
thick. Gametophytes showing the development of antheridia and 
Fig. 89. —Osmunda cinnamomea: photomicrograph of vertical section from the notch toward 
the base of the prothallium showing four stages in the development of the archegonium—chromo- 
acetic acid; safranin, gentian-violet; from a preparation by Dr. W. J. G. Land. Negative by 
Miss Ethel Thomas. X425. 
archegonia are not likely to be more than 2 or 3 mm. long and 1 or 
2 mm. thick. Near large plants, look for small sporelings, not more 
than 1 or 2 cm. in height. Dig very carefully and you may find the 
gametophytes attached. The soil should be examined for smaller 
specimens. Most of the gametophytes will be found at a depth of 
1 to 3 cm. Fix in chromo-acetic acid. 
No one has yet succeeded in raising the prothallia from the spores. 
The prothallia always contain an endophytic fungus, but even when 
this is present no one has succeeded in raising prothallia. 
The prothallium of Ophioglossum is harder to find or, perhaps 
it would be better to say, harder to recognize, for it is also subter- 
