362 SECTIONAL TRANSACTIONS.—K. 
The hybrids between L. perenne and F. rubra have so far proved to be completely 
sterile, but an extremely low degree of fertility has been found in hybrids from other 
crosses. It has thus been possible to raise a very small number of second generation 
lants. 
Other intergeneric crosses have been attempted, but so far unsuccessfully. 
Two types of interspecific crosses which have been made are of special interest 
and will be referred to. These are :— 
Phalaris arundinacea with Phalaris bulbosa. 
Festuca rubra with Festuca elatior var. arundinacea. 
The hybrids between F. rubra and F.. arundinacea are distinctly weaker than those 
between fF. rubra and Lolium perenne. 
19. Dr. Macerecor Sxenr.—The Supply of Iron in Nutrient Solutions. 
The successful use of Van der Crone’s nutrient solution for water cultures of oats, 
and the divergent results obtained by other investigators, led to work on the factors 
concerned in iron supply. It was found that chlorophyll formation was best in plants 
to which iron was supplied as citrate ; chloride was less efficient and phosphate least 
so. The difference was, however, only marked in the early stages of growth. Dry 
weight was equal in the citrate and chloride plants and lower in those supplied with 
phosphate. Differences in the solubilities of the three salts do not explain the results. 
Absorption by the cell wall and the presence of insoluble compounds in contact with 
the roots are of importance in maintaining the iron supply. 
20. Mr. J. C. Watter.—The use of the Katharometer in Studying the 
Output and Intake of CO, by Leaves. 
21. Lecture by Dr. D. H. Scorr, F.R.S., on The Transformations of 
the Plant World in Geological Time. 
Tuesday, September 1. 
Mornine. 
22. Discussion on Deviations from the Normal Course of Seaual 
Reproduction in Plants. 
(a) Prof. Dame Heten Gwynne-Vavueuan, D.B.E. 
Conjugation among the lower thallophyta is associated with the formation of a 
resting cell; among higher plants, in which greater facilities exist for food storage, 
conjugation ceases to be of value as a means of increasing the food supply, and its 
chief significance, apart from possible stimulus to development, seems to lie in the 
opportunities of variation entailed by the association of two unlike sets of chromosomes 
and their subsequent distribution in meiosis to form new combinations of paternal 
and maternal elements. Where the organism is not completely adapted to its environ- 
ment, or where the environment is changing, this may be of special significance, but is 
ineffective without frequent exogamy. 
Deviations from the normal course of sexual reproduction in plants appear to be 
associated in very many cases with the abandonment of exogamy, and often with the 
disappearance of motile cells. 
Meiosis may persist, however, after conjugation has ceased to occur, and the latter 
is then replaced by the fusion of two female nuclei, a female and a vegetative nucleus, — 
or two vegetative nuclei. Such fusions may be delayed, even though nuclear — 
association has taken place, until just before meiosis. 
The diploid nuclear content is not essential to the formation of the sporophyte, anda 
true parthenogensis or euapogamy may occur in forms with well-marked alternation 
of generations. Similarly, diploid gametophytes have been recorded. Polyploidy 
may in certain cases be associated with the occurrence of such forms. 
Where the gametophyte is the main phase in the life-history, the suppression of — 
conjugation may be followed by the disappearance of the sexual phase and of the 
sporophyte ; where the sporophyte is the dominant phase, it may persist by means 
of budding. 
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Lata 
