TRANSACTIONS OF SECTION K. 1008 
that in Thallophytes the plant is always an oéphyte, whether ‘actual’ or ‘ potential.’ 
Hence they believe that in Thallophytes the plant should show throughout 
the reduced number of chromosomes, reduction hypothetically taking place 
immediately upon the germination of the odspore. If this were true it would lend 
some support to the idea of the intercalation of the sporophyte, but at present there 
is not the slightest evidence for these assumptions. On the contrary, in the only 
Thallophyte in which chromosome-counting has been successfully accomplished 
(Fucus) Professor Farmer and Mr. Williams find exactly the reverse; the plant 
has throughout the fw// number of chromosomes; reduction first takes place in the 
odgonium, immediately before the maturation of the ova, and on sexual fusion the 
full number is restored, to persist throughout the vegetative life of the plant. 
Fucus is, no doubt, a long way off the direct line of descent of Archegoniatz, but 
still it is a striking fact that the only direct evidence we have goes dead against 
the idea that the sexual generation (and who could call a Fucus-plant anything 
else but sexual?) necessarily has the reduced number of chromosomes. This fact 
is indeed a rude rebuff to deductive morphology. 
I am disposed to regard the different number of chromosomes in the two 
generations observed in certain cases among Archegoniate not as a primitive but 
as an acquired phenomenon, perhaps correlated with the definiteness of alternation 
in the Archegoniatz as contrasted with its indefiniteness in Thallophytes. In 
Fucus, in flowering plants, and in animals the soma or vegetative body has the full 
number of chromosomes. With these the sporophyte of the Archegoniate agrees ; 
it is the odphyte which appears to be peculiar in possessing the half-number, 
so that if the evidence points to intercalation at all, it would seem to suggest that 
the odphyte is the intercalated generation—obviously a reductio ad absurdum. 
I do not think we are as yet ina position to draw any morphological conclusions 
from these minute histological differences, interesting as they are. 
The question how the number of chromosomes is kept right in cases of 
apospory and of apogamy is obviously one of great interest, and I am glad to say 
that it is receiving attention from competent observers. 
SEXUALITY OF FUNGI, 
Only a few years ago De Bary’s opinion that the fruit of the ascus-bearing 
Fungi is normally the result of an act of fertilisation was almost universally 
accepted, especially in this country, Although the presence of sexual organs had 
only been recorded in comparatively few cases, and the evidence for their functional 
activity was even more limited, yet the conviction prevailed that the ascocarp is at 
least the homologue of a sexually produced fruit. The organ giving rise to the 
ascus or asci was looked upon as homologous with the odgonium of the 
Peronosporex, the supposed fertilising organ either taking the form of an 
antheridial branch as in that group, or, as observed by Stahl in the lichen Codlema, 
giving rise to distinct male cells, or spermatia. More recently there has been 
a complete revolution of opinion on this point, and a year ago or less most 
botanists probably agreed that the question of the sexuality of the Ascomycetes 
had been settled in a negative sense. This change was due, in the first place, to 
the influence of Brefeld, who showed, in a great number of laborious investigations, 
that the ascus-fruit may develop without the presence of anything like sexual 
organs; while Mdller proved that the supposed male cells of lichens are in a 
multitude of cases nothing but conidia, capable of independent germination. 
The view thus gained ground that all the higher Fungi are asexual plants, 
fertilisation only occurring in the lower forms, such as the Peronospore and 
Mucorinez, which have not diverged far from the algal stock. The ascus, in 
particular, is regarded by this school as homologous with the asexual sporangium of 
a Mucor. This theory has been brilliantly expounded in a remarkable book by 
Von Tavel, which we cannot but admire as a model of clear morphological 
reasoning, whether its conclusions be ultimately adopted or not. 
Still, it must be admitted that the Brefeld school were rather apt to ignore 
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