20 
Lang . — Studies in the Morphology and 
also might have a suspensor. The study of a number of series of sections 
through young plants attached to prothalli established the existence of 
a well-developed suspensor in Helminthostachys ; this was recorded in 
a brief preliminary note. 1 These additional series also provided two 
embryos of intermediate age which were present alongside successful plants. 
It is obviously desirable that the embryogeny of Helminthostachys 
should be fully worked out on normal and adequate material. My material 
was collected in the Barrawa Forest Reserve in Ceylon in the month of 
March, after the annual inundation of the forest had subsided. All the 
female prothalli found bore young plants or mature embryos. Since 
Campbells experience in the same locality in February, 1906, was similar, 
no unfertilized prothalli being found, his inference 2 that there is an annual 
periodicity in the development of the prothallus of Helminthostachys seems 
highly probable. The prothalli probably grow from the spores shed in the 
previous season, and are fertilized at maturity, the young plants developing 
forthwith and the prothalli perishing. Under the peculiar conditions that 
obtain in this locality the collection of a full series of prothalli and embryos 
may be a matter of great difficulty, and it seems advisable to publish 
the results obtained from the study of the imperfect material at my dis- 
posal. The main features of the embryogeny will therefore be described in 
this paper, and the form of the young plant followed until the horizontally 
growing rhizome is established. The consideration of the vascular anatomy 
will be deferred until the next number of these studies. 
Before considering the early stages in the embryogeny it may be well 
to point out that in the advanced embryo three tiers or regions can be 
distinguished. The tier next the archegonial neck will be referred to as the 
upper tier of the suspensor ; it often remains as a large undivided cell. 
The next tier also takes no part in the formation of the embryo proper and 
will be spoken of as the second tier of the suspensor. The third tier gives 
rise to the organs of the embryo plant and is comparable to the whole 
embryo in those Ophioglossaceae that have no suspensor. The embryo 
proper can be distinguished into a hypobasal half adjoining the suspensor 
and an epibasal half occupying originally the end of the embryo furthest 
from the archegonium. It will be shown that the large foot is formed from 
the hypobasal half, while the stem-apex, first leaf, and probably also the first 
root, all arise from the epibasal half. The two tiers of the suspensor (A, j- 2 ) in 
relation to the young plant or embryo are seen in PI. Ill, Photos. 10 
and 12. This anticipation of the organization of the mature embryo will 
make the significance of the younger stages clearer as they are described in 
order. 
The very young embryos were in almost all cases more or less 
contracted or broken down ; the limits of the cavity, in which the embryo 
1 Ann. of Bot., xxiv, 1910, p. 611. 2 loc. cit., p. 54. 
