1 82 Farmer and Digby. — Studies in Apospory and 
first, but ultimately a strand is formed which marks the primary vascular 
tissue of the young embryo. The root is formed endogenously, and bores 
out through the tissues in the posterior direction, whilst the first leaf and 
the apex of the stem are differentiated from the superficial cells of the 
excrescence. The embryo has thus a somewhat broad attachment to the 
prothallium (Fig. 76), but there is no structure that can be definitely 
recognized as a foot. 
The chromosomes have been counted in dividing nuclei of the pro- 
thallium (Figs. 70, 71), in the antheridia, and in the embryo (Figs. 72, 73). 
The numbers obtained indicate, as in Scolopendrium , a certain degree of 
variation, but they quite preclude the occurrence of reduction in the sense 
of meiosis. For the prothallium, 60 is the probable number ; the variation 
on either side, in nuclei favourable for counting the chromosomes, was very 
small. In the case of the embryo, on the other hand, whilst some nuclei 
showed 60, others exhibited a mean number of about 78. 
It thus seems probable that the actual number of chromosomes is not 
quite constant even in the nuclei of the same individual. Possibly, as will 
also appear later, this variation in chromosomes is to be associated with 
other varying characters presented by these Ferns. 
We searched a considerable number of prothallia to ascertain whether 
or not there is a migration of nuclei, such as occurs in the apogamous (but 
not aposporous) Lastrea ps-m. var. polydactyla , but with a negative result. 
The importance of this becomes sufficiently obvious when it is remembered 
that there is no reduction in this plant, for with the omission of meiosis 
from the life-history there would appear to be no grounds for anticipating 
the intercalation of a process tending to duplicate the number of chromo- 
somes. Indeed, with the cessation of the meiotic phase, it is difficult to 
understand how any such process could persist. 
In comparing this Fern with the other varieties of Lastrea , it is im- 
possible, especially if we fix our attention on the sporophyte, not to be 
struck by the relatively small number of chromosomes which the nuclei of 
its sporophyte contain. It is true that the other varieties diverge from the 
type in the matter of their complement of chromosomes, but their differences 
are insignificant as compared with that shown by the plant under considera- 
tion. If, however, we consider the gametophyte only, the difference is very 
slight, and the question naturally arises as to whether we are not, in this 
Fern, dealing with a case which is the correlative of those which we have 
hitherto considered ; that is, whether, regarded from the standpoint of the 
chromosomes, the gametophyte character has not been impressed on the 
sporophyte, instead of the reverse process which we have encountered, for 
example, in the varieties of the Lady Fern. In the latter, we have every 
reason for believing that the gametophyte has arisen directly from the 
sporophyte, and owing to the absence of meiosis it has become endowed 
