A. H. Lees 55 



Case 4. This case did not come under the personal notice of the writer 

 but.was reported by a grower. The case consisted of a temporary rever- 

 sion caused by the attack of Capsid bugs. 



All these four cases seem to come under one general set of conditions. 

 In the first three and probably in the fourth a considerable impetus to 

 growth has been thrown on to weak buds. In case 1 dormant buds were 

 stimulated by a ring above; in case 2 a bud that was just ceasing growth 

 was suddenly urged into fresh growth by removal of all other active 

 growing points and in case 3 weak laterals of the current season were 

 acted on in the same manner. In the absence of exact physiological 

 data it is impossible to make any sort of definite statement, but the 

 conclusion that may warrantably be drawn from these cases is that the 

 plant reacted under a special stimulus to growth. 



DISEASE REVERSION. 



Under this heading are grouped certain cases which have come 

 under the writer's notice and which appear to be produced by causes 

 other than those treated under the heading of "Temporary Reversion." 

 They are of course similar in every way to those that appear in growers' 

 plantations. The differences between normal and reverted leaves are 

 perhaps most clearly brought out by a comparison of a normal and 

 reverted shoot taking each, leaf by leaf, comparatively. Such a dual 

 series is shown in Figs. 18 and 18a to 23 and 23a. In the two younger 

 leaves (Figs. 18-19, 18a-19a) there are no marked differences but in the 

 third leaves (20 and 20a) the blunter appearance of the lobes is already 

 evident. In the enlargement of the lobe D, two points may be noticed. 

 First the lobes are coarser, especially the apical one which is quite broad 

 at the base in the reverted specimen and narrow in the normal one. 

 Secondly the submain veins tend to become reduced in the reverted leaf, 

 the top veins showing a characteristic bending round so that they nearly 

 rejoin the submain vein instead of running to a point on the margin. 

 These two characters are general throughout the leaf and constitute the 

 best numerical means of ascertaining the extent of reversion. A still 

 more advanced stage is shown in the enlargement of D of Figs. 21 and 21a. 



Figs. 21-23 and 21a-23a show successive stages in loss of submain 

 veins from the midrib; 21a has four and 22a only three. These leaves 

 were the fourth and fifth from the apex at the time of examination and 

 are about the same size, but in the 10th leaves from the apex (Figs. 23 

 and 23a) a marked difference in size in favour of the normal has appeared. 

 These may be taken as fair types of the two kinds. The changes that 



