236 
METHODS IN PLANT HISTOLOGY 
while the asters take the violet. Achromatic structures are very 
prominent during these three divisions, but become less and less 
conspicuous as division progresses and 
before the intrasporal stage is over, the 
radiations are scarcely demonstrable. 
For the older sporophytes of Mar- 
chantia, it is better not to cut the 
whole receptacle. Remove the radiating 
branches. The sporophytes are in radi¬ 
ating rows, alternating with the branches. 
A piece 2 mm. wide can be cut so as to 
include two of the radiating rows, one on 
each side of the stalk, and such a piece 
will include early stages in other rows. 
By taking such care, you can get median 
longitudinal sections of nearly all the 
Fig. 70 .—Pellia epiphylla: photo¬ 
micrograph of longitudinal section of 
sporophyte still inclosed in the 
calyptra. The deeply lobed spore 
mother-cells are dividing. Eastman 
Commercial Ortho film, Wratten E 
filter (orange); arc light; J. Swift and 
Son 1-inch lens; exposure, 1 second. 
Negative by Dr. P. J. Sedgwick. 
X30. 
Sporophytes. For class Fig. 71 .—Pellia epiphylla: photomicrograph of spore 
work, 5 to 10 IX is a good germinating while still within the capsule. Fixed in 
n r , r p. chromo-acetic-osmic acid, and stained in safranin, gentian- 
tnickness, but lor figures, violet, orange. Negative by Miss Ethel Thomas. X276. 
especially the reduction 
mitoses in the spore mother-cells, the sections should not be thicker 
than 2 or 3 / 1 . 
