686 TRANSACTIONS OF SECTION K. 
7. Third Interim Report on the Structure of Fossil Plants. 
See Reports, p. 408. 
8. Report on Peat Moss Deposits.—See Reports, p. 410. 
9. Report on Studies of Marsh Vegetation.—See Reports, p. 409. 
10. Report on Experimental Studies in the Physiology of Heredity. 
See Reports, p. 410. 
1l. The Preservation of Natural Monuments. By Professor CoNWENTZ. 
FRIDAY, AUGUST 2. 
The following Papers were read :— 
1. The Embryology of Pteridophytes. By Professor F. O. Bowsr, /.2.S. 
Comparative embryology of the sporophyte stands at the moment in a dis- 
credited position as compared with other avenues to an opinion on the phylogeny 
of Pteridophytes. The chief reasons for this are :— 
1. Distrust of segmentation as bearing any constant relation to the genesis of 
arts. 
f 2. The apparent inconstancy of position and of number of the parts in embryos 
of near affinity, e.g., in the different species of Lycopodium. 
3. The obvious physiological opportunism which dominates the development of 
certain embryos, notably those of the Leptosporangiate ferns. 
4. The inconstancy of the occurrence of a suspensor, and of certain tuberous 
and suctorial swellings. 
The position commonly held at the moment is that stated by Goebel,’ that 
‘oot, shoot, and haustorium are laid down in the positions that are most beneficial 
for their function.” This implies that there is no generally constant feature in the 
conformation of embryos in vascular plants. To those who accept this as true, 
embryology cannot form a secure basis for general comparisons, or for phylogenetic 
argument. 
A revision of the embryology in the whole series of Pteridophytes, in which the 
facts relating to the Psilotacez form now the only conspicuous gap, has led to the con- 
clusion that the form is not so inchoate as Goebel’s statement implies. There is one 
point comparable in them all, which does not appear susceptible of disturbance on 
a basis of opportunism—viz., the position of the apex of the axis relatively to the 
primary segmentation. The position, number, and time of origin of the primordial 
leaves may vary, roots may also vary im number and position and time of appear- 
ance, and haustoria and tuberous swellings may be large or small, present or absent, 
but a comparison of embryos shows that the apex of the axis bears a constant posi- 
tion in the epibasal hemisphere. 
The time of initiation of the epibasal hemisphere varies according to the 
presence or absence of a suspensor, and in different types it may he directed 
towards, or away from, the archegonial neck. But whatever these variants, the 
apex of the definitive axis lies at a point coincident with, or in very near proximity 
Organography II., p. 246. 
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