SECTIONAL TRANSACTIONS.—K. 365 
the leaf or sheath which enclosed it in its younger stages and that if the growing-point 
of the plant is reached the result is the death of the plant. This disease resembles 
those caused by H. teres and H. avene more than it resembles smut diseases, and many 
of the phases of the three Helminthosporiwm diseases can be brought into alignment. 
H. sativum must now be added to these three as a fourth species parasitising 
British cereals. 
Some interesting features of culture work on these organisms, and additions to the 
knowledge of the conidial, pycnidial, and perithecial forms of fructification will be 
described. 
30. Miss I. Maxweti.—The Distribution and Specialisation of Black 
Rust in Scotland. 
The object of this research is to determine whether the specialisation of Puccinia 
graminis is the same as that recorded for England, and in particular to find out if the 
strain on the common couch (Agropyron repens) can infect the oat. 
Infected couch and oat were found growing together and varying in degree of 
infection in inverse ratio to their distance from the diseased barberry. Either the 
two strains are identical or the barberry must have carried a double infection. 
Oats and couch are being grown to try the infection from ecidia produced on 
barberries which were infected with teleutospores from oat and couch respectively. 
31. Miss A. V. Hay.—The Morphology and Anatomy of Juvenile and 
Adult Leaves of the New Zealand varieties of Sophora tetraptera 
(J. Mull). 
A brief account is given of the phenomenon of youth and adult stages common 
in plants of the New Zealand flora with special reference to those exhibiting the 
divaricating juvenile growth form, and, in particular, to the varieties of Sophora 
tetraptera (J. Mull). 
: The different growth phases of the latter may be set out as follows :—Var. micro- 
_ phyla (Hook, f.), seedling, juvenile (divaricating shrub), adult (tree); var. grandiflora 
- (Hook, f.), seedling, adult (tree); var. prostrata (Kirk), seedling, adult (divaricating 
shrub). 
: The morphological and anatomical features of the leaves of the different growth 
_ stages of the varieties microphylla and prostrata are described and discussed in the light 
of the generally accepted theories of youth and adult forms, and also in relation to 
_ Cockayne’s theory explaining the phenomenon in the N.Z. varieties of S. ietraptera. 
: 
B32. Miss E. D. Braty.—Physiological Zygomorphy in Certain Seedlings. 
: Working with hypocotyls, it has been found that some react to gravity more 
readily, when stimulated in the cotyledonary plane, than the intercotyledonary. 
; This phenomenon is strikingly shown in seedlings of Lupinus sp., in which the 
presentation time for the intercotyledonary plane is as much as four times as great 
as the presentation time for the cotyledonary plane. The latent time is slightly 
longer in seedlings stimulated in the intercotyledonary plane. Thelarge difference in 
_ the presentation time indicates that it is the perception of the stimulus, rather than 
_ the response, which is influenced by the plane in which the hypocotyl is stimulated. 
3 Attempts have been made to see how far any correspondence can be traced between 
_ this eo and the light relations, or with the internal structure, of the various 
see gs 
z 
SUB-SECTION K.—FORESTRY. 
Thursday, August 27. 
Morninc. 
1. Presidential Address to Section K by Prof. J. Luoyp WILtiaMs on 
The Phaeophyceae and their Problems. 
