Observations made in London Squares 555 



OBSERVATIONS MADE IN THE GARDENS OF 

 LONDON SQUARES. 



There is only one tree in the garden of Cavendish Square 

 which shows anything like a witch's broom, and it is, perhaps, 

 only a pigeon's nest. There are several, however, which ex- 

 hibit the "witch's scrubbing brush" in profusion. A lime 

 tree (the tree nearest to Harley Street) shows them best. 

 From the ground upwards are seen a number of flattish 

 bosses from which twigs grow. The twigs in this instance 

 are much longer than those seen in oaks, and thus destroy to 

 some extent the likeness to a brush, The growths are, how- 

 ever, of the same nature as in the oak. They result from the 

 irritation caused by the deposit of the eggs of some insect, by 

 which bark-buds, otherwise dormant, have been stimulated 

 to growth. This same tree was last summer much infested 

 with aphis, its leaves being covered with honey-dew. 



A huge growth, probably caused by some irritation of like 

 kind (but not growing twigs or making any sort of broom or 

 brush) may be seen high up on one of the largest Plane trees. 

 If the observer will seek a garden-seat under the tree nearest 

 to Scott's bank and look up into the tree in front of him 

 towards the north, he can scarcely miss it. It is a big, bossy 

 mass, a yard across and probably more than a foot thick. 

 Is it a cancer ? we shall be asked. The answer must be that 

 it is a tumour, and perhaps as near " a cancer" as a tree can 

 grow one. It differs, however, from all cancers in animals in 

 that it will do no harm to the tree which has grown it. Such 

 tumours are instructive examples of the long persistence of 

 results after the removal of the cause which set them going. 

 The cause was probably the irritation of an insect many years 

 ago, and the insect probably ended its local existence soon 

 after the growth started. The tree, however, had no power to 

 control a process which it had commenced, and went on year 

 after year adding to growth which was of no sort of use either 



