April 2^, 1886] 



NA JURE 



009 



A curious modification in the cells of the leaf is seen 

 sometimes in some species of Oxalis. In plants grown 

 in well-shaded spots the cells of the pallisade parenchyma 

 are not so much elongated as in those exposed to more 

 light, but are more conical. In the beech too a similar 

 difference is noted. In the sun the leaf is smaller and 

 thicker, and has several layers of pallisade parenchyma, 

 while in the shade it is large, but thin, and the pallisade 

 layer is single. 



Looking still at terrestrial plants, the general character 

 of the vegetation in different regions illustrates well the 

 general correspondence between environment and struc- 

 ture. In the tropics we find vegetation luxuriant, huge 

 trees with evergreen leaves, masses of interlacing 

 climbers, a great tendency of the smaller plants to be- 

 come shrubby, even some annuals simulating the bushes 

 of temperate regions ; the presence of palms, tree-ferns, 

 &c. Higher in latitude these disappear, bushes are more 

 numerous ; the trees become less luxuriant and more 

 compact, the leaves smaller and more rigid ; annuals are 

 found in larger proportion, while mosses and lichens 

 make their appearance. Still higher, where the influence 

 of winter begins to be felt, the trees have as a rule 

 deciduous leaves, which do not cover them for more than 

 half the 5'ear. Where the leaves remain evergreen, as in 

 the Coniferae, they are specially constructed to resist cold, 

 being strongly cuticularised and altered in form so that 

 the ratio of surface to bulk is much lessened. In the 

 pines especially they are much elongated, becoming 

 almost needle-like in shape. Their structure is adapted 

 especially to check loss of water by evaporation, and to 

 protect the delicate parenchyma of the interior from the 

 access of the cold. 



Various modifications of structure accompany also a 

 parasitic habit of life. Here the effect of the environment 

 must be taken to include all the various interferences 

 with the normal habits of plants brought about by the 

 changes in the mode of nutrition which the parasite now 

 pursues. The modifications will be seen to be greater 

 the more complete the parasitism. We may consider 

 what are perhaps the most striking cases, those found 

 among flowering plants. Of these we have certain 

 Scrophulariacea; which show but little modification. 

 They take only part of their nourishment from their 

 hosts, being furnished with means of living exactly like 

 other plants. The dependence of the different species of 

 Orobanche on the host is more complete. The outward 

 form of the plant is there ; the long stem, bearing small 

 leaves. In accordance with the mode of nutrition, all the 

 food being absorbed from the host, th; power of absorb- 

 ing food or obtaining energy from without the latter has 

 gone ; the leaves contain no chlorophyll, and are conse- 

 quently brown and shrivelled. In Cuscuta the process of 

 degradation has gone still further, even the leaves having 

 disappeared. The degradation does not affect merely the 

 vegetative structure, but the reproductive organs also 

 suffer, as may be seen in the common mistletoe. This 

 change, however, seems only incidentally to be connected 

 with the environment, being rather the result of the dis- 

 turbance of the constitutional equilibrium brought about 

 by the changes in nutrition. 



A comparison of lower forms of parasitic habit with 

 others which, though about as high in the scale, do not 

 depend on a host for support, reveals similar degradation 

 brought about by the nature of the mode of life Their 

 power of independent growth has much decreased, their 

 cells often appear to contain no nuclei, or these are made 

 out with difficulty ; they have no chlorophyll, nor any of 

 the other colouring matters which are present in the non- 

 parasitic forms. 



Some curious modifications of structure are associated 

 also with different climbing plants. These are not of so i 

 general a nature as those already alluded to, being notice- 1 

 able only on particular species. In Ainpclopsis hcdcracea, I 



and in A. VcitcJtii the curved tips of the tendrils, after 

 touching a surface, form adhesive disks, which secrete 

 and pour out a resinous cement which attaches the tendril 

 to the surface. Bignoiiia capreolata has a similar but 

 more elaborate development, while Ficus repe?!s, which 

 climbs like the ivy by rootlets, exudes similar material 

 from its rootlets, this being somewhat of the nature of 

 caoutchouc. 



Not only the vegetative parts of plams thus exhibit 

 modifications of structure according to the nature of their 

 environment, but the same thing can be seen especially 

 with regard to the structure of the reproductive organs. 

 The ways in which these are adapted to different modes 

 of fertilisation would however pass far beyond the limits 

 of this article. 



NOTES 



Pkof. Melsens, the distinguished chemist, has died at 

 Brussels, at the age of seventy-two. 



By the death of the Rev. W. W. Newbould, F.L.S., which 

 took place on April 16, at Kew, at the age of sixty-seven, a 

 figure has passed away very familiar to the frequenters of the 

 meetings and library of the Linnean Society, the British Museum 

 herbarium and reading-room, and the herbarium at Kew. At 

 the time of his student-days at Cambridge, where he was a pupil 

 of Prof. Henslow, Mr. Newbould acquired a love of botany, 

 which became the recreation, and latterly the pursuit, of his life. 

 His interest was, however, confined to a study of our native 

 British plants, the limitation of the species, and especially their 

 geographical distribution. Several of our local county floras 

 owe much to his co-operation ; and of some particular groups of 

 plants he had a very exact knowledge. But his speciality was 

 an intimate acquaintance with the botanical bibliography of this 

 country ; in his knowledge especially of the older literature he 

 was almost unrivalled. 



Many will regret to learn of the death of Thomas Edwards, 

 the Banff naturalist, so well known through his Life l>y 

 Mr. Samuel Smiles. Edwards was born on Christmas 

 Day, 1 8 14, at Gosport, Portsmouth, where his father, a 

 private in the Fifeshire Militia, was stationed after returning 

 from the Peninsular War. Early in life Thomas Edwards 

 showed indications of a great love of animals, insects, and 

 creatures of every description. He made extensive excursions 

 in search of specimens, and many amusing anecdotes are told 

 to illustrate his extreme f jndness for even the most repulsive 

 subjects in the animal creation. At eleven he was apprenticed 

 to a shoemaker, and at the age of eighteen he had undergone 

 many severe trials. He joined the Militia, but his love of 

 insects proved fatal to his military ambition. In his twentieth 

 year Edwards went to work as a shoemaker at Banff, and there 

 he pursued so successfully his researches in natural history that 

 he added a great deal to his scientific store of knowledge. For 

 fifteen years he carried on the most of his researches by night, 

 and he had many narrow escapes by reason of the eagerness 

 with which he pursued his object. He completed, however, a 

 splendid collection, and in 1846 exhibited it in Aberdeen. The 

 exhibition was a failure, and he had to sell the collection for 

 20/. to defray the expenses. He then set to work to form 

 another collection, and was mo t successful. His researches 

 added greatly to the knowledge of natural history, as he em- 

 bodied his new discoveries in papers written to scientific maga- 

 zines. In 1866 Edwards was elected a member of several 

 scientific societies. Latterly he had acted as Curator of Banff 

 Museum. After the publication of his biography by Smiles, 

 Edwards's genius was publicly recognised by a presentation of 

 333/. made to him in Aberdeen, and he was awarded by the 

 Queen a pension of 50/. a year. 



