393 
Life-history of Notothylas. 
columella and spore-forming layer, agree with Anthoceros. 
That, moreover, in all species one finds capsules in which 
a columella is present, but where the cells of the columella 
are formed throughout similarly to the other sterile cells of 
the capsule, and may be very easily separated from one 
another. The columella of such capsules is not developed, as 
in Anthoceros , independently of the spore-forming layer, but 
arises as a secondary differentiation within the spore-chamber, 
and in this respect agrees with the columella of the Moss- 
capsule. Again, in his conclusions he says : ‘ In many 
(perhaps all ?) species of the genus Notothylas there are 
capsules that possess no columella, and the examination of 
half-ripe sporogonia shows that this is not due to the eventual 
separation of the cells, but that no columella is ever differ- 
entiated.’ These conclusions were drawn from a study of 
the four species mentioned above. In N. fertilise as many 
capsules were found without the columella as with it, and in 
no case did the columella extend farther up than the middle 
of the capsule. The other species possess a columella. 
According to Gottsche 1 , N. fertilis is identical with N. val- 
vata , and there is reason to believe that N. valvata is the same 
as N. orbicularis 2 , the species here under consideration. 
The question to be answered then is what is the origin of 
the columella? Does it arise as in Anthoceros ? 
This work, the results of which are set forth in the fol- 
lowing pages, was taken up at the suggestion of Dr. Douglas 
H. Campbell of the Leland Stanford Jr. University. 
It may be well first to give a brief outline of the method 
used, as the results will thereby be more fully understood 
and appreciated. All specimens were fixed in chromic acid 
(i per cent, aqueous solution), remaining in the fluid about 
two hours ; then, after washing repeatedly in water for about 
two days, they were brought gradually into 70 per cent, 
alcohol, where they remained until wanted. In this way all 
1 Leitgeb, loc. cit., Heft V, p. 40, footnote. 
2 Gray’s Manual, revised edition, p. 727, 
