254 BARTHOLOMEW—ABNORMAL 
thalli which are partially fused, their archegonial ends being free 
and turned in opposite directions. In Professor Farmer’s speci- 
men, to which I have referred, there were two prothalli apparently 
more sharply separated than in the one I describe, but the 
archegonial end of each was dfrected towards the micropyle, and 
the prothalli lay therefore somewhat side by side, one, however, 
overlapping the other. In this feature Professor Farmer's 
specimen differed from my one, where the prothalli are antiposed. 
The explanation of the abnormality which naturally occurs to 
one is that two of the four potential megaspores of the sporocyte, 
instead of one as is usual, have germinated and formed each 
a prothallus ; but the solitary specimen I have for examination 
furnishes no material for a critical opinion. 
I may, however, add this, It is evident that an embryo 
formed from an egg of one of the chalazal archegonia in my 
specimen would have its cotyledons forced towards the micropyle 
in germination, whilst the apex of the radicle would in vain push 
against the hard shell around the chalaza. May it be, then, that 
it is through an anomalous prothallial development of this kind 
that those occasional abortive attempts at germination of the 
seed are to be explained, in which the cotyledons emerge first of 
all through the micropyle, the radicle does not issue, and the whole 
seedling, therefore, dies soon through want of an absorbing 
primary root ? 
Since the above was written, a series of ovules have been cut 
by the microtome in the Botanical Laboratory for the purposes 
of a demonstration series from the excellent material collected at 
Crookston, on the borders of Midlothian and Berwickshire, from 
which my specimen was obtained, and one of these ovules shows 
conspicuously the features of multiplication of prothalli; so much 
so, that I have included, by permission, an illustration of it (Fig. 
Bin Plate xlix.) side by side with the figure of my own specimen. 
The section figured shows an arrangement of prothalli more 
resembling that in Professor Farmer’s specimen. At s, there is 
evident separation of the archegonial ends of two prothalli, at $; 
the line of separation is still evident, and at s, there is the limit 
of the prothallus which approaches nearer the micropyle, and in 
which two archegonia, a!, are visible. At a » is the only archego- 
nium visible in the other prothallus, but in other sections of the 
ovule more archegonia are visible. That in this ovule a third 
