102 
Notes. 
with some degree of regularity in this species, but it is not constant, 
and is not found with any clearly defined outer limit in 0 . vulgatum 
or reticulaium ; thus far I admit the validity of Rostowzew’s criticism 
of my preliminary statement (Beitr. z. Kenntniss der Ophioglosseen. 
i. Oph. vulgatum, L., Moscow, 1892). On looking more carefully 
into this question, however, I have found that a band of superficial 
cells, differing in origin and segmentation from the surrounding cells, 
may be recognized as the spor angiogenic band ; this gives rise to the 
sterile septa, the sporogenous groups, and the external wall of the 
sporangia ; the band usually consists of two longitudinal rows of 
cells, possibly referable in origin to a single row, but there is some 
variety of detail. The observations have been made on three species, 
viz. O. vulgatum, L., 0 . reticulaium , L., and O. pendulum, L. 
The band, at first undifferentiated, subsequently forms (i) arche- 
sporia at intervals, (ii) sterile septa which intervene between them, 
and (iii) the outer sporangial walls. The cell-groups which give rise 
to septa and to archesporia are sister cell-groups, having a common 
origin, and no difference can be seen between them in early stages ; 
the distinction only becomes apparent as the archesporia attain their 
characteristic denser contents, and the difference is thus functional, 
not genetic. The archesporium of the single sporangium has not 
been found to be referable in origin to a single cell, and it is not 
defined by the first periclinal wall of the cells of the sporangiogenic 
band. These facts are all compatible with a theory of the origin of 
the spike of Ophioglossum by septation from a simple sporangium of 
the Lycopodinous type, and the sporangiogenic band may be com- 
pared with the band of cells, sometimes a single row, or two or three, 
which, after periclinal division, give rise to the archesporium of 
Lycopodium. 
The development of the sporangia of Botrychium and Helmintho - 
stachys has also been traced, but these facts do not bear so directly 
upon the question of the nature and origin of the Ophioglossaceous 
spike as those derived from the study of Ophioglossum. 
Abnormalities have played a large part in former discussions upon 
the morphology of the spike in the Ophioglossaceae. While recognizing 
the obvious correlation which exists between vegetative development 
and spore-production, it has been concluded that the abnormalities 
in this family do not form a sufficient basis for argument, certainly 
not when the conclusions drawn from them are in opposition to the 
