52 Leaf Character in Reverted Black Cu7'ra7its 



the older wood but produced normal though rather small leaves from 

 the one year old wood. A few weeks after, a similar ring was made just 

 below the one year old wood of B, but at first it produced no result. The 

 whole plant at this time was suffering rather severely from the combined 

 effects of aphis and a too hot and dry atmosphere with the result that 

 the foliage became brown and dropped off and the plant took on a resting 

 condition as in winter. Being of no further use apparently, it was put 

 outside. After a few weeks the heavy summer rains caused the plant 

 again to put out leaves, this being the second time during the season. 

 This time, however, shoot A which had previously produced reverted 

 leaves from the old wood showed perfectly normal leaves (from the buds 

 formed in the axils of the first crop of reverted leaves). The portion above 

 the ring had died. Shoot B this time produced reverted leaves from the 

 dormant buds on the old wood in the same way that shoot A had done 

 earlier in the season. The top portion of shoot B above the ring had also 

 died. Outline drawings from a leaf of the second crop of shoots B and A 

 are shown in Figs. 1 and 2. These two shoots therefore had reversed 

 their behaviour, A producing first reverted leaves and then normal and 

 B producing first normal and then reverted. Since they both belonged 

 to the same plant it is clear that it could not be reverted in the ordinary 

 disease sense. 



Case 2. In order to test the effect of cutting back during the summer 

 season a bush growing in the open had about three inches of growth 

 cut away from every growing tip. (The original idea was to test the 

 character of the foliage issuing from the weak lateral buds immediately 

 below the pruning cut.) Owing to the lateness of the season very little 

 growth occurred. This was, however, sufficient to show that the leaves 

 produced under these circumstances were of the reverted type. Luckily, 

 a shoot in the middle of the bush had been overlooked. This shoot 

 had almost, though not quite, ceased growth in length and the stimulus 

 placed upon it by removal of the active growing points from all the 

 other leaders caused it to react in a very interesting manner. Fig. 3 

 shows a half outline drawing of the leaf that had just been formed 

 before the stimulus began. It has fine submain veins and is almost 

 normal in margin. The next leaf (Fig. 4) has lost a vein, the margin has 

 become irregular and the leaf undersized. The next leaf (Fig. 5) is similar 

 though somewhat larger, while in the next (Fig. 6) the veins have been 

 reduced to three. The last in the series (Fig. 7) has regained the five veins 

 and has become normal again in margin and outline. This therefore is 

 clearly a case of temporary reversion. 



