i 78 The Meeting of the British Association at York. 
other hand if the subject chosen be too narrow, the treatment is 
apt to become excessively technical, and the whole discussion is of 
limited interest, and may even languish in the absence of sufficiently 
instructed specialists. 
The first discussion, which took place on Friday morning, 
August 3rd, was really divided into two parts. Dr. Scott began, 
with a comprehensive title—“ Some Aspects of the Present Position 
of Palaeozoic Botany,” but considerations of time compelled him to 
limit himself to “the difficult question of the position of the ferns 
in the Palaeozoic flora,” “the difficulty arising from the accumulation 
of evidence showing that most of the so-called Palaeozoic ferns 
were in reality seed-plants.” Dr. Scott showed, in his luminous 
address,—that “ a large body of true ferns of a simple type—the 
Primofilices of Mr. Arber—existed in Carboniferous times,” while 
it is probable that true Marattiaceous ferns also existed side by side 
with these. 
Discussion on the Origin of “Coal-Balls.” 
The second part of the discussion dealt with the formation 
of the well-known calcareous nodules found in the coal seams of 
the Lower Coal-Measures. 
Professor Weiss, in a preliminary paper, gave a short general 
account of the nature and occurrence of the coal-balls, from 
which it appeared that they are calcareous concretions containing 
petrified plant remains, occurring at very few, perhaps at only a single 
horizon, and that while shells are not found in the nodules of the 
seam itself, they are common in other nodules found in the roof. 
This fact led Binney to suggest that the nodules were formed by 
solution of the calcareous salts of the shells and their re-segregation 
round certain centres in the submerged peaty mass of vegetable 
matter. A similar mode of formation has been suggested for the 
calcareous nodules (Dolomitknollen) which occur in certain seams 
of the Westphalian Coalfield, where marine shells are found in the 
shaly roof of the seam. Lomax on the other hand holds that the 
nodules were not formed in situ, but were water-borne to their 
present position. 
Miss Stopes followed and brought forward all the evidence, 
obtained from her recent work on the subject, in favour of 
the origin of the coal-balls in situ. In the first place there is no 
crushing of the plant-tissues within the balls, while the coal around 
is crushed and bends over the balls. Then the same plant can 
