291 
Ophioglossum (C heir og loss a) palmatum , L. 
which are not held as pinnae in the usual sense of the word. The spikes 
underwent a parallel pleiogenetic amplification. Sometimes this amplifica- 
tion took the form of repetition of spikes like the original one, but seated at 
points apart : this is duplication or interpolation. Sometimes two spikes 
are seated near together, or upon a common stalk ; in the latter case they 
may merely show distal branching. These are conditions indicative of 
chorisis. Other variants may also be found. But in all these amplifications 
the spike is the unit throughout, and the branchings are not to be interpreted 
in terms of pinnae as normally understood. 
Morphology of the Ophioglossaceous Spike. 
The above discussion has been concerned with the more elaborate 
types of the spike-development in the genus Ophioglossum. It has not 
touched the question of the morphology of the spike itself, which has been 
held as the unit in the amplifications seen in Ophioderma and Cheiroglossa. 
In my ‘ Studies. II. Ophioglossaceae (1896)’, the evidence up to that date was 
summarized and weighed with a view to tracing the probable affinity of the 
family, and incidentally the morphological character of the fertile spike 
which is its most notable feature. This required a careful balancing of 
evidence for and against alternative views. Of these the one indicated 
affinity with the Sphenophyllales and Lycopodiales, the spike being regarded 
as a result of amplification from the sporangiophore, or ultimately from the 
sporangium. The alternative indicated an affinity with the Filicales, in which 
case the morphology of the simple spike would be referable in some form or 
another to a pinna or a coalescence of pinnae. The evidence up to 1896 ap- 
peared to me to favour the former alternative, and that conclusion was stated 
with ample illustration and discussion of the details on which it was based. 
Since then considerable advance has been made in various directions which 
bear upon the question. The researches of Lang 1 and of Bruchmann 2 have 
greatly increased the knowledge of the gametophyte and of the embryology. 
The discovery by Lyon 3 of the suspensor in Botrychium obliquum (followed 
recently by the description of a like body in Helminthostachys by Lang 4 ) 
at first sight appeared to strengthen the Lycopod affinity, but the demonstra- 
tion of a like organ in Danaea by Campbell 5 put matters back in statti quo. 
A second line along which recent advances affect the question is the 
anatomy of some of the earlier types of the Filicales. Kidston and Gwynne- 
Vaughan, by comparison of fossils which are plainly of Osmundaceous 
alliance, whether or not they are Osmundaceae in the modern sense, have 
shown it to be highly probable that the structure seen in the modern 
Osmundaceous stem is in the main the result of an up-grade development 
with medullation from a protostele. This has paved the way for similar 
1 Ann. of Bot., xvi, 1902. 2 Bot. Zeit., 1904, and Flora, 1906. 3 Bot. Gaz., Dec., 1905. 
4 Ann, of Bot., 1910, p. 611, 5 Ann, of Bot., 1909, p. 691. 
