A. H. Lees 53 



Case 3. This case occurred in a cutting bed. When found, the single 

 shoot arising from the cutting had divided (during the summer) into 

 two shoots, one longer and one shorter. The reason for the division could 

 not then be ascertained, but the original terminal growing point had 

 absolutely disappeared and growth had been taken up by lateral buds 

 immediately below. In Table I are found details of the important points. 

 These are the venation of the leaf, the mites found in the axillary buds 

 and the leaf margin and shape. The whole plant was free from mite 

 infection at the time of examination. Characteristic temporary reversion 

 is shown by the basal leaves of both longer and shorter shoots {B and C). 

 In shoot B the two basal leaves (Figs. 10 and 11) have only three submain 

 veins but a recovery is quickly made to five in leaf 4 (Fig. 13) and main- 

 tained to the end. Recovery of the margin is slower. Shoot C shows 

 much the same transition. The first two leaves (Figs. 14 and 15) though 

 broad are markedly reverted. The leaf venation has recovered by leaf 3 

 (Fig. 16), but the margin not until leaf 6 (Fig. 17). 



The effects of the check to terminal growth, however, are not con- 

 fined to the two shoots B and C; it has also marked influence on the 

 undivided base of the cutting, here called shoot A. Normality of veins 

 and margin is maintained up to leaf 9, namely five leaves behind the 

 critical point. Leaf 10 was very small, deformed and of a general re- 

 verted type. Leaf 11 was unusually large but quite normal as if extra 

 food supplies had been diverted into it. Leaves 12 (Fig. 8) and 14 

 (Fig. 9) were both peculiar, first in having no bud in their axils and 

 secondly in having lost one lobe of the leaf, in one case the left lobe, in 

 the other the right. Both were rather reverted in margin and 14 (Fig. 9) 

 was reverted in venation. Leaf 13 like leaf 11 was normal though of 

 extra large size. 



There is evidence here of considerable disturbance to normal growth. 

 Leaf 10, which was the first leaf to feel the eftect of the kilhng process 

 going on in the then terminal, apparently had its food supplies cut off 

 so that a very deformed and small leaf resulted. The food which should 

 have been available for the developing terminal apparently went into 

 leaves 11-14. Such a process may be often observed in brassica plants 

 where the terminals have gone blind; the leaves immediately below, 

 even if cotyledons, become large and dark green. No reason for the 

 moment can be suggested why leaves 12 and 14 lacked one lobe nor 

 why neither had an axiliary bud. Shoots B and C each began under the 

 same stimulus that caused the extra large top leaves of shoot A and 

 both showed temporary reversion of the leaves. 



