258 Chronicles of Science. [April, 



of a branch of a healthy plant is even sufficient to produce the 

 disease. Variegation may be produced by various causes, debility in 

 the seed, dampness of the ground, want of light, &c. It can be pro- 

 pagated by layers, buds, or grafts, but not, under ordinary circum- 

 stances, by seeds. Yariegation is partial decoloration or want of 

 strength to produce the green grains of chlorophyll ; if the decolora- 

 tion is general, it causes death. None of the higher plants, except a 

 few which are parasitic, can exist if entirely deprived of chlorophyll ; 

 though a perfectly blanched branch may occasionally lead a parasitic 

 life on the remainder of the plant. 



Cultivation of Cinchona. — Many climates are now found to be 

 adapted to the profitable growth of the Cinchona, or Peruvian bark. 

 In addition to its introduction into St. Helena, reported some time 

 since, it is now grown on a small scale in the Azores. In our 

 own governments of Madras and Bengal its cultivation is rapidly 

 extending. From a report recently published by Mr. 0. B. Clarke, 

 Assistant-Superintendent of the Botanic Garden at Calcutta, it 

 appears that the increase in the number of plants at the Darjeeling 

 plantations during the year ending March 31st, 1869, was 673,654, 

 making in all over three million plants, belonging to the three 

 species Cinchona officinalis, succirubra, and micrantha, the area 

 covered on the 1st of April, 1869, being 965 acres. There is also 

 a smaller Government plantation at Nunklow, in the Khasia Hills. 

 The tallest plants grown at Darjeeling are 19 feet high. Mr. 

 Broughton, chemist to the Cinchona plantations in the Madras 

 Presidency, believes that all the sub- varieties are permanent, and 

 have been produced by artificial hybridization ; but that hybridiza- 

 tion seldom takes place in nature. 



The Chair of Botany at the College of Science, Dublin. — This 

 appointment, vacant by the resignation of Professor Wyville Thom- 

 son, has been conferred on Mr. W. T. Dyer, author of ' A Flora of 

 Middlesex.' A vacancy is thus occasioned in the Professorship 

 of Natural History in the Eoyal Agricultural College at Ciren- 

 cester. 



5, CHEMISTBY. 



A veby unexpected fact has been published by Professor Wanklyn. 

 It has usually been considered that the affinity of chlorine for the 

 alkali metals was very energetic, and when it is remembered that 

 antimony and arsenic burst into flame when introduced into this gas, 

 it was reasonable to suppose that the reaction between chlorine and 

 sodium would be even more violent. Mr. Wanklyn, however, has 

 shown that when chlorine gas is passed over metallic sodium — 

 even when the metal is fused, and, whilst in a state of fusion, shaken 



