March 23, 1876] 



NATURE 



403 



\ 



his observations. The list of sun-spots at the end of the 

 publication and the various extracts from the note-book 

 will prove very useful to those who are engaged in 

 researches of a similar kind. The observations seem to 

 have been conducted with great care, and Dr. Lohse gives 

 us in every case the exact method by which the measure- 

 ments have been made. 



If we endeavour to review a work which is not being 

 continued, at least for the present, we rather turn to the 

 actual results of the observations than to a mere list of 

 accumulated facts. This list, no doubt, may prove here- 

 after to be the most important part of the work, yet it is 

 only made important by those who discuss the observa- 

 tions. The more doubtful and hypothetical part, con- 

 taining the conclusions, is therefore the better test for the 

 moment, for we must not forget that without a guiding 

 idea a mere tabular arrangement of facts is useless. 



One of the most curious results of Dr. Lohse seems 

 to be the discovery of a period of fifty days in the eruptive 

 activity of the sun. Dr. Lohse took from the drawings 

 of protuberances published by the Spectroscopic Society 

 of Italy, the area of the protuberances as shown in the 

 drawings for each day, and made a curve in which the 

 times of observation formed the abscissae and the area 

 of the protuberances the ordinates. This curve first 

 shows maxima and minima corresponding to maxima and 

 minima of sun-spots. It next shows a short period of 

 fifty days. During the years 1871, 1872, and the be- 

 ginning of 1873, this period was well marked. From the 

 middle of 1873, however, the whole solar activity became 

 so small, owing to its chief periodicity of eleven years, 

 that these secondary maxima cannot any more be distin- 

 guished. 



We turn now "to the spectroscopic observations, in 

 which Dr. Lohse was led to somewhat similar conclusions 

 as Mr. Lockyer. It is a well-known fact, that while 

 nearly all the elements standing at the positive end of the 

 electro-static series are found in the sun, we have as yet 

 obtained no decided evidence of the more electro-negative 

 elements. On the other hand, it is not probable that the 

 sun should not contain so many bodies which play an 

 important part in our world. Both Mr. Lockyer and Dr. 

 Lohse came to the conclus ion that we must look in the 

 outer and cooler layers of the sun's atmosphere for evi- 

 dence of the metalloids, but while Mr. Lockyer assumes 

 that they exist as well in the hotter parts of the solar 

 envelope, but under such conditions that we cannot 

 identify their spectra. Dr. Lohse assumes that they do not 

 exist except in the outer layers of the corona. Dr. Lohse 

 is thus forced to assume a force in the sun which drives 

 all the more electro-negative elements away from its 

 centre. This is an hypothesis which we cannot accept, 

 unless we have independent evidence in its favour, or 

 unless it is the only one which will account for the facts ; 

 just as we could not accept Mr. Lockyer's hypothesis, if 

 we had no evidence of changes in spectra produced by 

 variations of temperature and pressure. Mr. Lockyer's 

 hypothesis has a decided advantage over that of Dr. 

 Lohse, for we have recently obtained such strong proofs 

 of the changes of spectra produced by a variation of tem- 

 perature and pressure, that we cannot help thinking that 

 had Dr. Lohse been acquainted with all these recent 

 experiments, he would have come to the same conclusion 



as Mr. Lockyer. This conclusion, indeed, seems inevitable, 

 if it is once assumed that the metalloids really exist in the 

 sun. It is important to mention that this presence of 

 metalloids in the sun is rendered still more probable by 

 the fact that the red and most likely cooler stars give 

 spectra containing fluted bands. 



It is interesting'to notice that Dr. Lohse finds many 

 of the unknown dark lines contained in the blue end of the 

 solar spectrum to be reproduced in the spectrum of a Her- 

 culis, and although weaker in that of a Orionis, while they 

 are absent in that of a Bootis. 



Dr. Lohse does not seem to arrive at any results dif- 

 fering much from those of other observers in his observa- 

 tions on facula: and sun-spots. It is a matter of regret 

 that he, most likely for the sake of brevity, does not 

 enter more fully into the explanation of his own views. A 

 discussion of ideas described in such a cursory manner 

 is impossible, as such a description is necessarily incom- 

 plete. 



We hope that Dr. Lohse will have occasion to follow 

 out his researches, and do not doubt that he will be 

 rewarded by most interesting results. 



Arthur Schuster 



OUR BOOK SHELF 



The Absorptive Glands of Carnivorous Plants. By Alfred 

 W. Bennett, M.A., B.Sc, F.L.S., Lecturer on Botany 

 at St Thomas's Hospital Read before the Royal 

 Microscopical Society, Dec. i, 1875. With one plate. 

 Mr. Bennett notices the occurrence in Drosera rottin- 

 difolia, Pinguicnla vulgaris, and Callitriche verna of 

 peculiar bodie?, which at first sight might be mistaken 

 for stomata, and consisting of two nearly hemispherical 

 cells filled with protoplasm. Each of the hemispheres 

 contain a darker nucleus-like spot, and each is surrounded 

 by a thin-walled cell containing chlorophyll. From these 

 hemispherical bodies are developed the papillae with thin 

 walls and containing chlorophylL Drosera and Pingui- 

 cnla are carnivorous, and Mr. Bennett suggests that 

 Callitriche may also be carnivorous, from the occurrence 

 of these peculiar bodies. It seems probable that they are 

 really as Mr. Bennett thinks, absorptive glands, and they 

 certainly bear a strong superficial resemblance to the 

 quadrifid processes found and described by Darwin in 

 Utricularia and Genlisea. The subject is a very interest- 

 ing one, and it is to be hoped that further research will 

 throw more light on the matter. It is rather difficult to 

 get a clear idea of the structures from the plate, which 

 seems a little out of drawing, and rather confusing. 



W. R. McNab 



Reseiia de las Rocas de la Isla Volcdnica Gran Canaria. 

 Per Don Salvador Calderon. (Reprinted from the 

 Anales de la Sociedad Espanola de Historia Natural. 

 Tomo iv.) Madrid 1876. 



In this work, which is appropriately dedicated to M. 

 Berthelot — to whom we owe one of the earliest descriptions 

 of the geology of these interesting islands — the author 

 gives some valuable information concerning the relations 

 of the different classes of volcanic rocks to one another. 

 He also describes some of the vast " Calderas " or craters 

 so characteristic of this group of islands, and notices the 

 theories which have been proposed to account fer their 

 origin. Of especial interest, however, is the account 

 which he furnishes of the nature and composition of the 

 different varieties of volcanic rocks, and the classification 

 which he proposes for them. It would appear from this 

 work of Sefior Calderon, that the true or " sanidine- 



