SECTIONAL TRANSACTIONS.—K. 489 
16. Dr. B. Murie, Briston Roacu.—Physiological Studies of Soil 
Alge. 
The ability of sub-aerial alge to fix atmospheric nitrogen in pure culture 
has been critically investigated in conjunction with Mr. H. J. Page, of the 
Rothamsted Chemical Department. ‘The results give no indication of fixation, 
as claimed by Wann (New York), there being a final recovery of 99.28 per 
cent. of the nitrogen supplied to the cultures, as against 99.25 per cent. from 
the control flasks. On the contrary, there is some evidence of denitrification 
in those cultures with the most luxuriant growth. Wann’s results are attribut- 
able to inaccurate methods of chemical analysis. 
17. Major C. C. Hursy.—On the Chromosomes of Rosa. 
Chromosome counts of Rosa give somatic numbers 14, 21, 28, 35, 42, 56. 
Q and g gametic numbers are equal, 7, 14, 21, 28 each, or unequal matroclinous, 
2, 3, 4,59:1¢. Allare 7 or multiples of 7, and during meiosis the chromosomes 
appear in definite strings of sevens, double or single. Male sterility arises 
through irregular behaviour of these strings. Analyses of 395 forms confirm 
the hypothesis that each string of seven represents definite characters, for 
various associations of paired and unpaired strings correspond with Linnean 
species. The string scheme provides a satisfactory method of classification for 
this polymorphic genus, based on cytological, genetical, and taxonomic results ; 
it also elucidates origin and evolution of species, for towards the Pole the 
number of strings increases. while towards the Equator it decreases. 
18. Mrs. Nesta Ferauson.—A Preliminary Account of a Survey of 
the Chromosomes of the Liliacee. 
Variations in number, size, and form of chromosomes in the Liliacee are 
illustrated. It is proposed to measure the size of the chromosomes—both linear 
dimensions and volume of chromatin—in the somatic and heterotypic divisions ; 
also to compare in various species the variation in size of the chromosomes and 
the forms of some of the bivalents. 
The underlying idea of the research is to study the chromosome groups in 
relation to phylogeny, and to test how far we have here another character for 
determining affinities Another aspect is a comparison of the chromosome 
complexes of the species of one area with those of another, widely separated 
area, in order to ascertain whether the constitution of the nucleus offers any 
indication of the lines along which development has occurred. 
19. Miss M. G. Campin.—A Chromosomal Survey of Certain Plant 
Families, with Special Reference to Genetic Relationships. 
In surveying an entire family from a chromosomal point of view certain 
conclusions emerge : (1) Within the family a certain ‘ type form’ of chromosomal 
configuration and cytological behaviour is recognisable. (2) The actual number 
of chromosomes in the different genera and species is of less importance in 
indicating affinity than the ‘type form,’ although sets of series, e.g., 12, 24, 
36... 60 in the Solanacez, are often observed and can be interpreted on a 
genetic basis. Solanacee and Ranunculacee are discussed in detail. Morpho- 
logical and cytological relationships of types aberrant to these families are 
discussed, and the significance of polypoidy in the genealogy of species is 
considered. 
20. Miss FE. M. Reus.—Chromosomes and Sterility in Muscari. 
Investigation shows that three lines of specialisation occur within the 
genus Muscari. Firstly, there is a series of forms which show progressive 
sterilisation of the inflorescence; every grade from complete fertility to com- 
plete sterility occurs. Secondly, there are variations in chromosome number ; 
there are diploid forms, tetraploid forms, and at least one pentaploid form. 
Lastly, there are, within forms with a similar chromosome number, marked 
variations in the relative size of the chromosomes, and also variations in the 
total bulk of chromatinic material. 
