396 SECTIONAL TRANSACTIONS.— K, K*. 



(2) It is common in nurseries where conditions are otherwise excellent for growth. 

 It is distributed in areas with very favourable climatic conditions for the summer 

 flush of growth. The practice of giving large quantities of growth-stimulating kraal 

 manure to nurseries may be partly responsible, although it has been shown that green 

 manuring is beneficial. At Bufielspoort, where the experiments were done, it was 

 found that the young badly diseased nursery plants showed the influence of kraal 

 manure, being much richer in such elements as potassium as compared with older 

 trees. 



The study of this disease has led to an incomplete study of the behaviour of 

 certain storage elements during growth. 



References. 



Dr. E. Doidge, ' Ring Blotch.' R. A. Davis, ' Citrus Growing in South Africa,' 

 Cape Town, 1924. 



AJternoon. 



Miss S. M. Stent. — The Classification and Distribution of the more 

 important South African Grasses. 



A revision of the genus Digitaria with key to the South African species and notes 

 on feheir chemical composition and economic value as pasture or hay grasses. 

 Diagnoses and illustration of undescribed species are also included. 



Miss I. C. Verdoorx. — The Botany of the Fountains Valley, Pretoria. 



This valley, which lies to the south of Pretoria and is the main entrance to the 

 town, is the source of the Aapies River. Its geological formation is interesting, 

 consisting as it does of the Pretoria shales and quartzite with an intrusion of dolomite 

 in the southern portion. The natural vegetation is disturbed in parts (by man) 

 and this short paper deals with its present aspect. 



Mr. A. 0. D. MoGG. — A Preliminaty Account of the Flora of Pretoria in 

 relation to the Geology. 



Miss A. M. BoTTOMLEY. — The Development of South African Mycology 

 and of the Cryptogamic Herbarium at Pretoria. 



Miss L. LuRiE. — Some Fungal Wound-parasites of Trees in the Transvaal, 

 with particular reference to the Polyporaceae. 



Prof. J. H. Priestley.— Lecture (semi-popular) on Frotn Lake to Veld : 

 A Study of the Water Relations of the Higher Plant. 



Saturday, August 3. 

 Joint Discussion with Section C {q.v.) and D on Gondwanaland. 



K*.— DEPARTMENT OF FORESTRY. 



CAPE TOWN. 

 Tuesday, July 23. 



Mr. C. E. Legat. — The Silviculture of Exotic Conifers in South Africa. 



Prof. A. W. Borthwick. — Geographical Distribution of Trees as a Guide to 

 their Cultivation. 



