256 Report S.A.A. Advancement of Science. 



Kei-apple at Cape Town, can be more readily accounted for as an 

 effect of intense illumination rather than of temperature. These 

 effects were prevented wherever sunrise rays fell on the plants. 



Another plant which has shown itself to be susceptible to the 

 early morning rays is the Scarlet Verbena. In this case 24 Verbena 

 slips were planted in a circular bed in the garden at Pretoria. Eight 

 of these were scarlet, and were planted together on the south-west 

 side. Not one of them rooted, whereas the remainder did. Amongst 

 the plants that succeeded was a scarlet one, and when it was observed 

 that that portion of the bed where they had failed had been in 

 shadow at sunrise, six more scarlet slips were cut from this one, and 

 were planted in the same place, when the shadow no longer fell on 

 it at sunrise. Four out of the six rooted. One of the two that failed 

 was in the shadow cast by a pine-apple seedling till 8h. 30m. 



During a successful experiment to try and revive some desiccated 

 Macrocarfas an observation was made which seems to connect 

 the foregoing results with the cloud-phenomenon of March 12th, 

 and to show that they were due rather to the action of light upon 

 chlorophyll-granules than to temperature. Three Macrocarpas form- 

 ing part of a hedge 7ft high, withered from the effects of the winter 

 of 1905. By September the foliage and epidermis were russet-red. 

 An experienced local gardener pronounced it impossible to restore 

 them by watering or by any other means. An examination of the 

 roots proved them to be healthy, and it was determined to try and 

 save the trees by the application of water to the epidermis. In order 

 to obtain a constant drip upon the stems, bottles were tied near the 

 top of each tree, neck downwards, and corked. A hole had been 

 knocked in the bottom, and another had been drilled through the cork. 

 When the bottles were filled with water from the bottom, a constant 

 drip took place which could 'be regulated by a plug of wood in the 

 cork. About 2 pints of water were allowed to fall on to the stems 

 in this way during the 24 hours. All the trees revived gradually. 

 New shoots were not put out, but the old branches and aciculated 

 leaves turned first yellow and then green, showing, in the writer's 

 opinion, that desiccation had resulted from too small a supply of 

 water to the protoplasm of the cells, and from too much sun. 

 It seems probable that the chlorophyll-granules were heaped 

 up on those cell-walls which were parallel to the incident light, and 

 as long as this continued the yellow colour remained. But when 

 sufficient water once more reached the protoplasm vitality returned, 

 and the granules resumed their functions under the influence of light. 

 There were two sprays in particular which supported this vie^Y of the 

 action going on within the cells. They were near the top of one of 

 the trees, and turned the usual canary-yellow. They were watched 

 for T3 days, and no sign of chlorophyll appeared. The branch to 

 which they belonged was then separated from the rest, and it was 

 found to spring from a node 2 inches above the drip of the water. 

 This was the first instance of the kind. The bottle was accordingly 

 raised, and within 48 hours the spravs turned green. It was con- 

 sidered in this case, as in that of the peas, which turned yellow 



