CHANGES OF COLOUR AND STRUCTURE OF FLOWERS. 43 



way, and flowers of this colour are now obtained from all parts of the 

 garden in profusion. The complete change of the exceptional plant 

 was also effected. Here, as in the case of Miss Jekyll's Iceland Poppies, 

 there can be no question of cross-fertilization, for no purple variety of 

 Nasturtium was known in the neighbourhood of Pretoria, and the 

 plants excited much interest when they were publicly exhibited. The 

 carefully carried out experiment could have only one explanation, and 

 it lay in the kind of sunlight which fell upon these plants when they 

 were fully exposed. We are irresistibly led to think of the many 

 historic cases — and naturally that of the Shirley Poppy, in which we 

 feel such a personal interest — where new species and new varieties have 

 been found, in the first instance, in some one spot and in no other, in 

 such circumstances that we cannot but believe that they originated 

 there. You see in the instances before you that under the sun's action 

 the so-called honey-guides will disappear, spots and markings will be 

 modified, and the colours so changed that gardeners will be ready to 

 admit that they have not seen such varieties before. 



By leading a main axis through a board overhead, and branches 

 through other boards at the side and at the back, the same plant has 

 been subjected in different regions to sunlight of different kinds. The 

 seed was allowed to drop, and was not screened artificially in any way 

 the next year. New varieties, never seen before in these experiments, 

 were obtained, and amongst them one that is well known to gardeners as 

 'Aurora,' in which flowers of very different colours are borne simul- 

 taneously. The appearance of these multicoloured flowers marks a 

 distinct stage in these experiments. They are of interest to the 

 botanist as indicating the inherent potentialities waiting to be stimu- 

 lated by sunlight, and to the practical gardener as the source to 

 which he may look for many new and pleasing colour-modifications 

 when once we learn how to control them. I have here several examples 

 of them, and you will see that in some cases the same flowers appear, 

 at adjoining or adjacent nodes, as are seen in the series of changes 

 from yellow to purple or from orange to chocolate, thus enabling us 

 to draw some very instructive conclusions regarding colouring matters. 

 All the multicoloured varieties arose in the first instance from screening 

 different regions of a plant so that full sun fell on them at different 

 times. The modifications then produced were found to be transmitted 

 by the seed under the same conditions of sunlight. 



From the commencement of these experiments each plant under 

 observation has had its separate page in the diary, and as the value 

 of any modification could not be anticipated the minutest detail was 

 entered. No pot was ever moved, except designedly, even one inch 

 from its assigned position, nor was it rotated on its axis. It soon became 

 apparent that the three colours — yellow, red, and purple — were associ- 

 ated with distinct altitudes of the sun as it moved from sunrise to sunset. 

 If a plant was given full sun at a low altitude any yellow pigment in 

 the flower was intensified, while purples could only be produced by the 

 sun at its highest altitudes — such as we experience in summer— and reds 



