TRANSACTIONS OF SECTION K, 687 
to, the intersection of the octant walls of the epibasal hemisphere, The position 
of the apex of the axis defines the polarity of the embryo; and as its position 
relatively to the basal wall is constant, that wall is itself the early indication of 
that polarity. 
There are two or three sources of disturbance, which veil the recognition of 
the polarity thus noted, as a constant feature in embryos :— 
1. The initial polarity is apt to be inverted, and evidence of such inversion may 
be found within definite phyla. Examples will be quoted in Lycopodiales 
(Selaginella and Iscétes); in Ferns (Marattiacee and Leptosporangiates); in 
Ophioglossaceze (Ophioglossum and certain species of Botrychium). 
2. Certain parts may be hastened forward in their development, or delayed, 
according to biological requirements, If leaves be precocious, the axis is apt to be 
delayed or dormant; but where most insignificant its constancy of position is 
indicated by the orientation of the leaves. 
3. Parenchymatous swellings may be formed of the nature of a‘ protocorm’ or 
of an haustorium (foot) ; these may distort the embryo in a high degree, and mask 
the relation of the ultimate shoot-apex relatively to the initial segmentation 
(e.g. Lyc. cernuum). But it is believed that in all cases that relation really exists 
The definition of such a polarity in the embryo presents it to the mind as a 
spindle of varying proportion upon which appendages may be borne. This is the 
obvious condition in Eguisetwm—the only one of the strobiloid sporangiophoric 
Pteridophytes in which the embryology is known. The condition of other 
embryos, even the most divergent, is believed to be due to modifications of a 
similar construction, susceptible of biological explanation. In extreme cases, 
suck as certain Lycopods, a peculiar embryologic phase—the protocorm—thus pre- 
cedes the regular vegetative shoot: this is held to be the result of a secondary 
specialisation. In others, such as Z. Selago and Phlegmaria, the development passes 
directly to a condition characteristic of the permanent shoot; these are believed 
to reflect more nearly the primitive history. In Ferns, as also in Jsoétes, the early 
polarity of the embryo is marked by the precocious development of the cotyledon. 
In Ophioglossacez this precocity varies ina high degree, and in many of them it is 
the root which is precocious, while the first leaves may be developed sometimes as 
insignificant scales. But under all these diverse proportions the embryo is so con- 
structed that the apex of the axis originates at, or in near proximity to, the centre 
of the epibasal hemisphere. 
2. Joint Discussion with Section D on the Physical Basis of Heredity. 
Opened by Professor S. J. Hicxson.—See p. 541. 
3. Some Advances in our Knowledge of the Pollination of Flowers. 
By Professor F, E, Weiss, D.Sc. 
MONDAY, AUGUST 5. 
The following Papers were read :— 
1. The Morphology of Aspergillus herbariorum. 
By Miss H. ©. I. Fraser and H. 8S. Cuamsers. 
Aspergillus herbariorum was first studied by De Bary in 1863. His investiga- 
tions were non-cytological, and in view of the very common occurrence of this 
fungus further knowledge of its development was felt to be desirable. Cultures 
were made on 3 per cent. agar-agar mixed with prune juice and cane sugar. 
_ The archicarp is more or less coiled, and is divided into three parts, all multi- 
nucleate. The apex of the coil forms a unicellular trichogyne ; below this is 
a considerably longer unicellular ascogonium, and below again a septate stalk, 
