TRANSACTIONS OF SECTION K. 739 



or with its roots wedged in the cracks of precipitous rock-faces overhanging the 

 rivers. The proportion of cone-hearing plants of this species was found to be 

 much smaller than in the case of E. eycadifolius. In both these species of 

 Encephalartos the growth of the stem appears to be monopodial ; the cones are 

 arranged symmetrically round the apex of the stem, which resumes growth after 

 the production of the cones. Some account was given of a third species of Ence- 

 phalartos and of the genus Stangena. The paper concluded with a summary of 

 general impressions resulting from a study of South African cycads, and with an 

 expression of thanks to Messrs. E. E. Galpin, J. Wood, and G. Rattray for 

 assistance afforded during the author's visit to the cycad country. 



[Mr. Seward, who communicated the above paper, stated that he had recently 

 received a letter from Professor Pearson, in which he gave an account of some 

 observations made by a lady who lives in the cycad country on the growth of a 

 male cone of Encephalartos villoms. On January 29 the cone was 2 inches high ; 

 on March 17 it had reached a length of 9i inches and a sweet odour was noticed. 

 On May 3 the sporophylls were found to be well open, and the cone measured 

 20 inches ; the smell had become decidedly unpleasant. On May 5 the cone was 

 21^ inches high, and the smell was horrible. On this date some small beetles 

 were caught among the sporophylls with thousands of pollen grains adhering to 

 their slender 'probosces.' The facts observed appear to afford good evidence in 

 favour of the view that Encejyhalartos is pollinated by insect agency.] 



Interim Report on Research on South African Cycads. 

 See Reports, p. 431. 



3. The Vegetation of Tenerife. ^y Hugh Richaedson, i/.-^. 



The author called attention to the accessibility of this island and its interest 

 to botanists. 



Factors influencing plant life are: (i) a porous volcanic soil; (ii) a low 

 rainfall (14 inches) ; (iii) sub-tropical temperature ; (iv) isolation. 



The very marked zones of vegetation between the sea-level and the peak 

 (over 12,000 feet) were noted by Humboldt and by Piazzi Smyth. This stratifica- 

 tion appears to depend on the dryness of the air as well as on temperature. 



Photographs and lantern-slides of the vegetation have been deposited with the 

 Botanical Photographs Committee (Nos. 278-302). 



Living plants from Teuerifl'e were on view in the greenhouses of the British 

 Botanical Association in York. 



The flora of the island has been described in detail by H. Christ in Ger- 

 man, and enumerated by F. Sauer in Latin. English readers will find Sir 

 Daniell Morris on ' Plants and Gardens of the Canary Islands ' in vol. xix. of the 

 ' Journal of the Royal Horticultural Society.' 



The vegetation of the nearly level commons near York is in instructive contrast 

 with that of Teneriffe. Here there are as many zones of vegetation in 12 feet 

 of vertical height as in 12,000 feet in Teneriffe. For instance. Erica Tetralix 

 occupies a very marked horizontal zone, intermediate between grass and heather. 

 In this case soil-water content is suggested as the determining factor. 



4. A Preliminary Investigation into the Metabolism concurrent with 

 Heat Production in some Avoids. By Miss C. B. Sanders. 



In connection with some histological work done last year by Dr. Church in the 

 Oxford Botanical Laboratory on the heat-producing tissues of Arum italicum, 

 I undertook a small series of observations of temperature in that species and 

 Dracunculus vulgaris, both in situ, on the plants, and with cut specimens. 



3 b2 



