4 2o SECTIONAL TRANSACTIONS.— K. 



in their radical development and the union they make with the rootstock 

 and the scion. The possible role of the graft union and the physiology 

 growth cycles in the stem pieces is discussed in relation to the so-called 

 rootstock influences. 



Semi-popular Lecture by Prof. E. J. Salisbury, F.R.S., on The living 

 garden (5.0). 



Saturday, September 12. 



Excursion to Southport sand dunes. 



Sunday, September 13. 



Excursion to Windermere, Wray Castle. 



Monday, September 14. 



Prof. J. H. Priestley and Miss L. I. Scott (io.o). (See Department of 

 Forestry, below.) 



Prof. W. Stiles, F.R.S., and Dr. W. Leach. — The relationship between 

 respiration intensity and oxygen concentration (10.30). 



Prof. R. Ruggles Gates, F.R.S. — The genetic survey as a method of 

 evolutionary study (11.0). 

 Hitherto very few, if any, intensive genetic studies have been made of 

 plants collected wild over a particular area. Ecotypes of various species 

 have been investigated in this way, and in a few genera, such as Crepis, 

 numbers of species have been brought together for a comparative genetic 

 study. The aim of the present work is, by collecting the wild seeds of a 

 genus at short intervals over a given area, to make an intensive genetic 

 survey of all the existing forms, their relationships and distribution. This 

 was done with Oenothera in eastern Canada, one hundred seed collections 

 being made in 1932 and about sixty more in 1935. The resulting cultures 

 show a surprising range of variation, including many new species and 

 varieties. By this method, which has been intensively followed for the 

 first time, much light is thrown upon the variations, geographic distribution 

 and phylogeny of the genus Oenothera. The fact that seeds from any wild 

 plant generally breed true to type, often showing minute differences from 

 plants of a neighbouring area, results partly from the presence of a ring of 

 fourteen chromosomes in all these forms. 



Dr. N. L. Penston. — Potassium in leaves (11.30). 



The changes during the day of dry weight, ash weight and potassium 

 content in leaves of potato and maize, and the osmotic pressure changes 

 of the sap in potato leaves, are shown in tables and graphs, and the results 

 discussed in relation to accumulation of solutes in the metabolising leaf. 



Mr. J. Gillespie. — The influence of certain chemical elements upon the 

 development of chlorophyll in plants (12.0). 

 This contribution records preliminary investigations of the relationships 

 and interrelationships of chemical elements in the formation of chlorophyll. 

 Iron, zinc and manganese in culture solutions have so far been employed. 



