Sept. 23, 1875] 



NATURE 



453 



relations of the beds. Another most valuable portion is the 

 series of tables of localities where the different formations 

 may now be studied, showing no less than 154 places 

 worthy of a geological visit within twenty miles of 

 London. With regard to the general structure of the 

 district, Mr. Whitaker is careful to refute the idea that 

 the Tertiary beds were deposited in an eroded hollow of 

 the chalk, as is often supposed ; unfortunately, however, 

 his section gives them rather the appearance of being so. 

 We should also notice that although, on the evidence of 

 fragments of Ammonites and Belemnites, he prefers to 

 refer the red beds of the Kentish Town section to the 

 Lower Greensand, none of this formation is represented 

 in the section as lying beneath this part of London. 



This convenient little publication, so full of valuable 

 and condensed information, for so small a sum, will be of 

 such great use to the members of the numerous field 

 clubs,; that we fear it will soon be out of print. What 

 are 500 copies among so many who would wish to 

 have it ? 



Sniola'id; or, Iceland, its Jokulls and FJalls. By William 



Lord Watts. (London : Longmans and Co., 1875.) 

 In a recent number (vol. xii. p. 333) we published a letter 

 from Mr. Watts announcing the important fact that he 

 had succeeded in crossing the Vatna JokuU. So far as is 

 known, this is the first time that this jokuU (which means 

 " glacier," and is probably cognate with the latter part of 

 our word \c-icle) has been crossed, and the fact is credit- 

 able to Mr. Watts's determination and perseverance. The 

 little book before us contains a narrative of an unsuc- 

 cessful attempt to accomplish the same object, made by 

 Mr. Watts in the summer of 1874. We regret to have 

 to say that the narrative is a disappointing one. It is 

 in the form of a rough diary, which seems to have been 

 sent to the press in its crude form and published with 

 little or no revision. A large portion of the book is 

 occupied with a statement of the many difficulties, petty 

 and serious, which Mr. Watts and his party encountered 

 in the journey from Reykjavik, by the Geysers, Hekla, 

 and the Myrdals JokuU to the Vatna Jokull, and there is 

 really very little information about the region through 

 which he passed. The entire narrative is extremely vague 

 and unsatisfactory, and if Mr. Watts has any literary 

 faculty, he certainly does not show it here ; the reading 

 of his narrative is a heavy task. Mr. Watts ought to 

 know a great deal about the region with which this narra- 

 tive is concerned, and especially about the jokulls in the 

 south of Iceland, and we would advise him to put this 

 information into a systematic form, make but little refer- 

 ence to the difficulties he encountered, obtain a few pho- 

 tographs on a much larger scale than the insignificant 

 things which appear in the present work, and we have no 

 doubt he would make a substantial contribution to our 

 knowledge of Iceland. The party succeeded in getting 

 only about half across the Vatna Jokull, when, from want 

 of the necessary means to go farther, they were compelled 

 to turn back, after Mr. Watts had rather unnecessarily 

 and sensationally planted the union jack at his furthest 

 point. Mr. Watts's carelessness, to put it mildly, extends 

 even to his use of language. The use of " laid " for " lay" 

 might possibly be justified by eminent precedents ; 

 "peninsular of rock" maybe a misprint, but ''pulverent" 

 is unjustifiable, and "molusc" is shocking. 



Perhaps the most tangible piece of information con- 

 veyed by Mr. Walts is contained in the following para- 

 graph :— 



" To sum up, this hitherto untrodden Vatna Jokull is a 

 mountainous tract, surmounted by a rolling plateau, con- 

 taining numerous volcanoes, one or more of which, upon 

 the north, appear to be in a state of pretty constant 

 activity, while r.umcrous others in all probability are 

 paroxysmal, most likely exhibiting all the phenomena 

 characteristic of (if I may be allowed the term; bottled up 

 volcanoes. This tract, together with the Odatha-hraun, 



and the centre of Iceland with its numerous mountains, 

 is a new volume of Nature, the first leaf of which has only 

 just been cut, but whose secluded fastnesses will amply 

 repay investigation." 



In an appendix Mr. Watts gives some information as 

 to equipment, which intending travellers in Iceland will 

 find useful. The map at the end is on too small a scale 

 to be of much use. 



The main object of Mr. Watts's [narrative is to attract 

 attention to Iceland and induce travellers to co-operate 

 in its exploration. We hope the work will serve this 

 laudable object, as there is no doubt Iceland presents a 

 handy and fertile field for explorers. Mr. Watts himself 

 deserves great credit for what he has already achieved ; 

 we hope he will continue his work, and in a future publi- 

 cation add something of permanentvalue to our know- 

 ledge of the interesting island. 



Report on the Neilgherry Loratithaccous Parasitical 

 Plants destructive to Exotic Forest and Fruit Trees. 

 By George Bidie, M.B., Madras. (Printed by E. Keys, 

 at the Government Press, 1874.) 

 Surgeon-Major Bidie has in this volume presented to 

 the Indian Government a report on the parasitical plants 

 which prove destructive to forest and garden trees on the 

 Neilgherries, and on the best mode of remedying the 

 evil. The whole of these destructive parasites belong to 

 one natural order, LoranthaceiE, represented in this 

 country by a single species, the Mistletoe, and to two 

 genera, Loranthus and Viscum. The fruit of the Loran- 

 thaceas is characterised by the envelopment of the seed 

 in a layer of a viscid substance, described by Dr. Bidie as 

 intermediate in character between resin and india-rubber. 

 Outside this viscid layer is a pulpy body which serves 

 as food for birds and squirrels. After devouring this the 

 seed is rejected, or, in the case of squirrels, passes unin- 

 jured through the body, and then adheres to the bark of 

 any tree on which it may be cast. If the immediate con- 

 ditions are unfavourable, the seed will be preserved in a 

 state capable of germination for a very considerable time 

 beneath its viscid covering. With regard to the mode of 

 germination. Dr. Bidie has nothing to add to the infor- 

 mation already furnished by Mr. Griffith and Dr. Hooker. 

 With reference to the mode of attachment between the 

 parasite and the host, the author states that although very 

 firmly attached, there is no actual interlacing of the 

 tissues ; and that in some instances, after maceration in 

 water for a few days, the parasite could be separated from 

 the host without much difficulty. It is noteworthy that 

 native Indian trees and shrubs do not appear to suffer 

 nearly so much from the attacks of the Loranthaceai 

 as introduced, especially Australian, species. One 

 foreigner, however, which appeared quite exempt from 

 their ravages, was the " blue gum," the Eucalyptus i^lo- 

 bulus, which has already so many other useful qualities 

 placed to its credit. Dr. Bidie asserts that the Loran- 

 thacea; derive their nutriment not from the descending 

 elaborated, but from the crude ascending sap of the host ; 

 hence their need for green foliage containing chlorophyll 

 and possessing stomata, in which other parasites are 

 deficient. The volume is embellished by fifteen large 

 lithographs representing the different species, and illus- 

 trating the structure of the fruit and the mode of parasitism 

 of the order. 



LETTERS TO THE EDITOR 

 \Thi Editor does not hold himself responsible for opinions expessea 

 by his correspondents. Neither can he undertake to return, 

 or to correspond with the -writers of, rejected manuscripts. 

 No notice is taken of anonymous communications. ^ 

 Personal Equation in the Tabulation of Thermo- 

 grams, &c. 

 Mr. Plummer, in his letter (Nature, vol. xii. p. 395), has 

 missed the point of the review of the work of the Meteorological 



