260 Professor A. Dickson on Development of 



The specimen I now exhibit is one which I found in the 

 neighbourhood of Biggar this winter. It is a small branch 

 of Pinus sylvestris, the extremity of which has been 

 destroj'ed — probably broken off. In consequence of this 

 accident a large number of the " bifoliar spurs " — about 

 twenty within a space of 3 inches below the injury — have 

 been stimulated to further development, resulting in the 

 production of a well-marked scaly bud placed between the 

 bases of the two foliage-leaves of the original fascicle. It 

 is further to be noted tliat the development of these buds 

 is stronger the nearer their position to the seat of injury. 

 In the more feebly stimulated spurs of this kind there is 

 simply a closed scaly bud springing from between the bases 

 of the two leaves of the fascicle ; but in the stronger ones, 

 near the seat of injury, the condition is somewhat different. 

 In these the extremity of the spur produced beyond the 

 bases of the two leaves of the fascicle does not immediately 

 produce a closed bud, but before doing so develops a 

 variable number of short but well marked foliage-leaves, 

 and, in the very strongest ones, these foliage-leaves have 

 secondary bifoliar spurs developed in their axils. 



Such a specimen is interesting in two ways — 1st, as a 

 well-marked case of the development, in consequence of the 

 removal of the extremity of the branch, of lateral buds, 

 which would otherwise have remained more or less dormant 

 — a phenomenon sufficiently familiar to tlie cultivator in 

 his operations of pruning or " cutting back ; " 2ud, as exhibit- 

 ing, in the stronger buds above-mentioLcd, a reversion to 

 the early or unspecialised condition in the development of 

 foliage-leaves on the prolonged axis of the stimulated spur. 



Abnormal development of this kind in Pinus is probably 

 not very uncommon. Many years ago I obrerved very much 

 the same condition in a branch of Scotch Fir, where the end 

 of the shoot had been destroyed ; and Dr Masters, in his 

 Vegetable Teratology, gives a figure where he represents the 

 " ordinary arrangement of the leaves in fascicles of three " 

 in Pinus Pinea, as contrasted with an "unusual arrangement 

 of leaves of the same plant in spires."* From his figure I 

 shouLl imagine that the abnormality represented was a spur 

 stimulated to further growth, as in my specimen, from which 

 * Vegetable Teratology, p. 86, fig. 41. 



