SECTIONAL TRANSACTIONS.— K. 387 



showed, on staining, less starch than similar patches covered during that interval, 

 in spite of the fact that the latter had received two hours less bright daylight than 

 the former. The starch was hydrolysed by the polarised sky light, for this effect was 

 not seen in cloudy weather, when polarisation was feeble. Further evidence was 

 also given of starch hydrolysis in the guard-cells of the stomata under similar condi- 

 tions, thus confirming the description given by the WTiter in 1925. 



Dr. A. B. Walkom. — A Comfarison of Australian and South African Fossil 

 Floras. 



Dr. H. Hamshaw Thomas. — Is Phyllocladus a Relic of the Mesozoic 

 Thinnfeldias ? 



In the earlier part of the Mesozoic period plants bearing leaves of the type consti- 

 tuting the form-genus Thinnfeldia were important constituents of the vegetation of 

 South Africa and of many other parts of the world. Very little is known of their 

 nature and affinities, and they may not all have been of one kind. Several writers 

 have linked them with the modern Phyllocladus, the curious conifer of New Zealand 

 and other islands of the Western Pacific. 



The author has studied the contents of a large deposit of leaves in the Jurassic 

 rocks of Yorkshire, which are close to the typical Thinnfeldias in their general 

 characters but differ somewhat in their stomatal structure. It seems impossible 

 to regard these foliar structures as phyUoclades. But with the leaves occurs a curious 

 type of cone which can be linked to them with a considerable degree of certainty. 

 This cone seems to have had a large verrucose fleshy axis in which numerous seeds 

 were partially embedded at ii'regular intervals. The seeds were larger than those 

 of Phyllocladus, but, like the Podocarps and other Taxaceae, had an epidermis with 

 numerous stomata. This structure seems more comparable with the ovulate strobilus 

 of Phyllocladus than with any other plant, and it would appear that the suggested 

 relationship cannot be disregarded. 



The apparent existence of a plant with pinnate leaves and a strobilus and seeds 

 referable to the Taxacea is most surprising. 



Prof. J. H. Neethling. — The Genetics of certain Characters in Wheat. 



Afternoon. 

 Excursion to Lion's Head. 



Friday, July 26. 



Discussion on The Origin and Evolution of the South African Flora 

 (Dr. R. Marloth, Prof. Bews, Prof. Compton, Dr. I. B. Pole Evans, 

 C.M.G.).' 



Dr. R. Marloth. — As an historical introduction to the vegetation, the physical 

 conditions and the climate of Southern Africa we may quote Thunberg's drastic 

 description (at the Cape, 1772 to 1776) of his experiences : ' Per dunas arenosas, 

 rivos infidissimos, Carro aridissimas, campos undulatos, Uttora falsa, coUes lapidosos, 

 alpes altas, praecipitia montium, fruteta spinosa sylvasque inconditas pericula vitse 

 adii, feroces gentes et bruta prudenter elusi. Thule hujus austraUs gazas speciosas 

 detegendi gratia laetus cucurri, sudavi et alsi.' 



The region of the Cape flora has been designated by later authors in various ways. 



^ Copies of a Guide to Botanical Survey Work are available to members through 

 the kindness of the Director of the Botanical Survey of South Africa, and can be 

 obtained from the Local Hon. Secretary, Section K, Cape Town. 



CC 2 



