io6 



SCIENCE-GOSSIP. 



smooth, clean trunk, during the past season, a 

 number of weak shoots had grown. I believe we 

 cannot tell how an apical cell, which seems to be 

 required before the growth of the branch can be 

 started, can be formed out of an ordinary wood 

 cell and be able to push its way through a layer of 

 bark a quarter of a century old so as to produce 

 the growth of twigs in question. There is an 

 original field here for study as well as a theme for 

 admiration. Perhaps my own discovery, published 

 in the "Proceedings" of the Academy many years 

 ago, on the nature of warts or excrescences on the 

 trunks of trees, such as we very often see on the 

 weeping willow, the garden cherry and other 

 trees, may furnish an explanation. It is briefly 

 this : new woDd is formed by germination from 

 original wood cells. These are added laterally 

 during the growing season. The last series of 

 cells born of the mother cells at the end of the 

 season become liber cells, and give the new layer 

 of bark for the coming season. But an occasional 

 cell does not change. It continues to be a wood 

 cell, though surrounded by others that have been 

 transformed to bark. It does not separate from 

 its woody matrix, but goes on forming its own 

 additional wood cells, and in the autumn its 

 layers of bark cells, in a sort of colony of its own. 

 These are developed in every direction round the 

 circular matrix, and the excrescence naturally 

 forms a circle. An excrescence sawn asunder 

 exhibits the annual growths of wood and the 

 annual deposit of bark, just as the mother trunk 

 does. I have never observed the excrescences 

 make branches. 



The manner in which buds are formed and 

 protected at different stages of their growth affords 

 endless pleasure. In Liriodendron the stipule en- 

 closes the younger growth, and, opening the bud, 

 we find the leaf-blade has its apex fast in the axis 

 between the branch and the petiole. No one can 

 doubt that the truncate leaf results from its early 

 casting in such a mould. In Magnolia we find the 

 same protection from the stipule, but the petiole 

 is not bent. The young leaves are folded longi- 

 tudinally. We can see some of the processes by 

 which nature makes Liriodendron differ from 

 Magnolia, but what induces the curving of the 

 petiole in one instance and the straightening in 

 another we have yet to learn. 



Though no reference is made of the fact in 

 descriptive botany, the manner in which the base 

 of the petiole folds over the young bud is distinctive 

 of the genus Rhus, or at least of many species, for 

 I have not examined all. The folding is so nearly 

 complete that no axillary bud is visible. In the 

 winter, after the leaves have fallen, we see by 

 the cicatrices that it was a fold of the petiole and 

 not an absolute over-growth. The cicatrix is 

 precisely like that formed by the fallen leaf of the 



horse-chestnut, and adds another suspicion to a list 

 already by no means brief that there is a closer 

 relation between the natural orders Sapindaceae 

 and Anacardiaceae than systematists generally 

 believe. Other species of trees, notably the plane 

 and yellow wood, have similar embracing petioles. 

 There seems no physiological advantage in these 

 cases. The young bud must have some protection 

 in infancy, and variety seems an essential part of 

 the order of things. All we can say is that this 

 form of protector is as good as any other. The 

 internal arrangement of the bud in Rhus is 

 interesting : two bud scales meet face to face, and 

 closely press their edges together. The interior is 

 a cavity, but densely filled with short, soft hair. 



A Sapindaceous plant allied to the horse-chestnut, 

 Kolreuleria paniculata, a small tree from Jap in, has 

 branches interesting from the fact that the petiole 

 disarticulates at a little distance above the base of 

 the petiole, leaving lacunose cicatrices, and giving 

 the branch a singular knobby and rough appear- 

 ance. Here again the teleologist will be at a 

 loss, and seeing that it is no disadvantage, we 

 can only say that it gives a pleasant variation to 

 the run of life. 



I might offer many illustrations, but enough has 

 probably been said to show how much of interest 

 the winter season may afford. 



CHRISTMAS ISLAND. 



A BOUT a couple of hundred miles south of the 

 western end of Java there lies a small island 

 about twelve miles long and seven miles broad, 

 named Christmas Island. Although possessing a 

 population of about a score of persons, one family 

 being English, it had never been explored by any 

 scientific person until quite recently. Dr. John 

 Murray, of Edinburgh, proposed to the trustees of 

 the British Museum to defray the expenses of such 

 investigations, and very properly the trustees 

 accepted the handsome offer. They selected for 

 the purpose of conducting the exploration Mr. 

 C. W. Andrews, of the Department of Geology in 

 the Museum. 



The area of the island is about ioo square miles, 

 the land reaching an altitude of 1,200 feet. The 

 fauna is very characteristic of its insular position, 

 and has produced a number of species peculiar 

 to the island. So far it has been found to be 

 very rich in new species, including all the land 

 birds, three new mammals, and over twenty of the 

 insects, out of thirty-five species collected. In 

 fact it is not often in these times that a scientifi- 

 cally trained collector and explorer has such 

 splendid opportunity of so largely adding to 

 knowledge in every department of biology and 

 mineralogy. 



