2 o 8 Lang . — On the Sporogonium of Notothylas. 
degree of development of the columella is quite consistent with this. Not 
only do Leitgeb’s observations on this species agree with what has been 
shown above as to the complete absence of a sterile columella in some 
capsules, but his few observations on arrested embryos suggest that a further 
grade of simplification may occur, in which only the endothecium is sporo- 
genous. Were no amphithecial archesporium cut off, the sporogenous 
tissue would be traceable downwards to four rows of cells in the stalk, as he 
describes and figures it. It would be of great interest to have these observa- 
tions, the possibility of which must be admitted, verified. Unfortunately 
satisfactory preparations were not obtained of the two dwarf capsules found 
in my material, and in all the other embryos and sporogonia examined it 
was clear that both endothecium and amphithecium had contributed to the 
sporogenous tissue. If such extreme forms occur they would seem to be 
infrequent and exceptional. 
The position of Notothylas among the Anthocerotaceae, and of the 
group as a whole in relation to the other Hepaticae, may in conclusion 
be briefly considered in the light of the facts as at present known. The 
point that has emerged from the study of this form of N. Breutelii , that 
the endothecium must be regarded as potentially sporogenous, is of con- 
siderable theoretical interest. It increases the justification for considering the 
central group of cells, which in all other Anthocerotaceae is wholly devoted 
to the formation of a sterile columella, as the original sporogenous tissue 
and the amphithecial archesporium as of secondary origin. The duty of 
producing spores would seem to have been transferred from the central 
to a more superficial set of cells. This may, I think, be regarded on com- 
parative grounds as probable, whether or not sporogonia are met with in which 
the amphithecial archesporium is absent. Leitgeb’s deduction that the colu- 
mella was to be looked on as originating by gradual differentiation within the 
sporogenous tissue does not, on the other hand, properly represent the facts. 
The causes of the change from the fertile to the sterile condition of the 
products of the endothecium must be looked for in influences acting on the 
primary meristematic tissue of the embryo, or on the intercalary zone of 
secondary meristem. The idea of a grouping of elaters in a central position 
to form the columella is not in this case in accord with the facts. The 
diverse results of the development of the similar embryos of the Antho- 
cerotaceae suggest the influence of nutritive factors acting on the young 
embryo when it is enclosed and dependent like a foetus in the uterus on the 
tissue of the gametophyte. 
The interest of the potentially sporogenous nature of the region usually 
developed as columella is independent of the question as to whether the 
species of Notothylas are to be regarded as primitive or reduced in com- 
parison with the Anthocerotaceae with larger sporogonia. I am inclined to 
regard the evidence as pointing to their being reduced forms. The appear- 
