SECTIONAL TRANSACTIONS —K. 433 



The congestion of vegetation in freshwater static waters has considerable 

 eflfect on the economic life of the countries. The growth of Eichhornia 

 speciosa encroaching upon the rice-fields and narrower waterways has become 

 such a serious menace that the Government have to take recourse to legisla- 

 tion for its eradication. Over-abundance of vegetable growth affects the 

 fish population, which yields good revenue to many provinces. 



The general features of the plant communities, with special reference 

 to freshwater and brackish water species, are discussed. 



Prof. R. B. Thomson. — The comparative anatomy of the male and female 

 cone scales in the conifers (10.25). 

 ' Inversed ' sporangial supply bundles in both male and female cone 

 scales of the conifers have been found to vary with the number and size of 

 the pollen sacs and of the ovules. Though the inversed bundles are abaxial 

 in the one case and adaxial in the other, the scales are considered to be 

 homologous structures which have become diflferentiated by factors associ- 

 ated with their function as male and female organs. 



Mr. R. D. Williams. — The frequency of chlorophyll deficient mutants in 

 red clover ( Trifolium pratense) ( 11 .0). 



About 150 simple recessive chlorophyll deficient mutants have been 

 identified in red clover, most of which have been shown by means of 

 diallel crossing of the recessives or the heterozygotes to be due to different 

 factors. The linkage relationships of many of the chlorophyll deficient 

 factors have been studied, and ten of these have been definitely located in 

 chromosome I, two each in chromosomes II, III and IV, and one in 

 chromosome VI. 



In order to determine the frequency with which chlorophyll deficient 

 recessive factors occur in the heterozygous condition in red clover, two 

 series of investigations were recently conducted — one with 22 normal green 

 plants of the Montgomery variety and the other with 25 normal individuals 

 of the English late-flowering variety. In the case of the Montgomery 

 variety, 13 of the 22 plants tested were found to be heterozygous for 22 

 chlorophyll deficients — 14 lethal and 8 surviving mutants, while in the case 

 of the English late variety, 14 of the 25 plants investigated were heter- 

 ozygous for 23 chlorophyll deficient recessives — 11 lethal and 12 surviving 

 genotypes. 



Dr. T. J. Jenkin and Dr. P. T. Thomas. — The breeding affinities and 

 cytology of Lolium species (i 1.30). 

 Inter-specific crosses between the following Lolium species have been 

 attempted : — 



1 . Lolium italicum. 



2. Lolium loliaceum. 



3 . Lolium perenne. 



4. Lolium remotum. 



5. Lolium rigidum. 



6. Lolium temulentum. 



The results already available are shown and very briefly discussed. 

 The parent species and some of their hybrid derivatives have been 



o 2 



