May 22, 1 884 J 



NA TURE 



vanic element, conclusively ascertained that the conductor 

 was in perfect working order right up to the top of the 

 mountain, we began the descent and the return journey 

 as rapidly as possible. We had no other choice, as the 

 storm and rain which every moment increased precluded 

 every possibility of doing more at that time. I had, how- 

 ever, some consolation in what already was done, my 

 apparatus standing 1900 feet above the disks. 



I left all the instruments to be used in connection with 

 the experiments at Mogilsau in hopes that the weather 

 would soon improve and allow me to return. The journey 

 to Reykjavik was performed in a downpour of rain and a 

 great storm. 



As I had anticipated, the " utstromnings " apparatus has 

 up to the present shown no signs of life whatever. I can see 

 it plainly with a good telescope from my residence, and 

 thus ascertain that it is in perfect order. In addition, I 

 have just received a message from Mogilsau, informing me 

 that the lower part is in perfect order too. Still during 

 the few favourable nights we have as yet experienced not 

 the slightest luminosity has appeared above the point in 

 question. 



If this be a negative result, it is a result, nevertheless, 

 of considerable scientific interest. 



The aurora borealis here has during the last few months 

 been far more discreet in its appearance than during the 

 first half of the winter. There is certainly, when the sky 

 is sufficiently free from clouds, here and there a faint 

 indication that the phenomenon does still exist, but such 

 signs of life are very weak and limited. 



I have at present no knowledge whether the aurora 

 borealis has displayed less activity in other quarters of 

 the globe during the winter than is generally the case, as 

 letters take a long time from and to this island, but the 

 Reykjavik people contend that the phenomenon displays 

 usually far more energy and intensity than has been the 

 case this winter. I am at present inquiring in various 

 parts of the island whether the absence of the aurora 

 borealis this winter has been noticed as generally remark- 

 able, or its appearance is the usual one in Iceland. 



In my last communication to Nature I intended to 

 have mentioned that I was curious to know what the 

 effect would be of a sufficiently strong aurora covering the 

 moon's disk. During the winter I have had several 

 opportunities of observing aurora? projecting over the disk 

 of the moon when full, but nothing more unusual is seen 

 than the light of the aurora borealis disappearing within a 

 radius of 5 3 to lo° around the moon. But in the appear- 

 ance of the latter there is no difference. 



Reykjavik, March SOPHUS Tromholt 



A lAR.X1VOROUSPLAXTPREYI.XG ON 

 I'ERTEBRATA 

 'AN interesting discovery has been made during the last 

 ■**■ week by Mr. G. E. Simms, son of a well-known 

 tradesman of Oxford. It is that the bladder-traps of 

 Utricularia vulgaris are capable of catching newly- 

 hatched fish and killing them. Mr. Simms brought in 

 me for examination a specimen of Utricularia in a glass 

 vessel, in which were numerous young roach newly 

 hatched from a mass of spawn lying at the bottom. 

 Numbers of these young fish were seen dead, held fast in 

 the jaws of the bladder-traps of the plant. I had never 

 seen Utricularia before, and am indebted to my colleague 

 Prof. Burdon Sanderson for the identification (if the plant 

 and a reference to Cohn's researches <m it. Mr. Simms 

 supplied me with a fresh specimen of Utricularia in a 

 vessel with fresh young fish and spawn, and in about six 

 hours more than a dozen of the fish were found entrapped. 

 Most are caught by the head, and when this is the case 

 the head is usually pushed as far into the bladder as 

 possible till the snout touches its hinder wall. The two 

 dark black eyes of the fish then show out conspicuouslv 



through the wall of the bladder. Rarely a specimen is 

 seen caught only by the tip of the snout. By no means a 

 few of the fish are, however, captured by the tail, which is 

 swallowed, so to speak, to a greater or less distance, and 

 I have one specimen in which the fish is caught by the 

 yelk sac. Three or four instances were observed in which 

 a fish had its head swallowed by one bladder-trap, and 

 its tail by another adjacent one, the body of the fish 

 forming a connecting bar between the two bladders. 



1 have not been able to see a fish in the actual process 

 of being trapped, nor to find one recently caught, and 

 showing by motion of the fore part of its body signs of 

 life. All those trapped were found already dead, but I 

 have had no opportunity of prolonged observation, and 

 it will be remembered that Mr. Darwin, in his account of 

 the trapping of Crustacea, worms, &o, by Utricularia, 

 states that he was not able to observe the actual occurrence 

 of the trapping of an animal, although Mrs. Treat of New 

 Jersey often did so. I think it probable that the fact 

 described by Mr. Darwin, and which is easily verified, that 

 the longer of the two pairs of projections composing the 

 quadrifid processes by which the bladders of Utricularia 

 are lined " project obliquely inwards and towards the 

 posterior end of the bladder," has something to do with 

 mechanism by which the small fish become so deeply 

 swallowed so to speak. The oblique processes, set all 

 towards the hinder end of the bladder, look as if they 

 must act together with the spring valves of the mouth 

 of the bladder in utilising each fresh struggle of the 

 captive for the purpose of pushing it further and further 

 inwards. On cutting open longitudinally some of the 

 bladders containing the heads and foreparts of the bodies 

 of fish, and examining their contents, I found the tissues 

 of the fish in a more or less slimy deliquescent condition, no 

 doubt from decomposition, for Mr. Darwin failed to detect 

 any digestive process in Utricularia. The quadrifid pro- 

 cesses were bathed in the slimy semi-fluid animal substance, 

 and the processes themselves appeared to contain abun- 

 dance of fine granular matter, possibly the result of 

 absorption, but the large quantity of surrounding animal 

 matter present rendered the observation uncertain. The 

 usual swarms of Infusoria were present in the decom- 

 posing matter. 



Specimens of the Utricularia with the little fish fast in 

 the bladder-trap, and their heads or tails hanging out, can 

 be well preserved in spirits, and show the conditions 

 well, notwithstanding that the plant becomes colourless, 

 and there is no longer the marked contrast been the 

 glistening white dead fish and the green bladders, which 

 in the fresh condition renders the combination of the trap 

 and prey conspicuous. 



Mr. Simms, by whose permission I write this, intends 

 shortly to publish an account of his observations himself. 

 I have advised him to endeavour to prepare spirit speci- 

 mens of Utricularia plants with numerous trapped fish 

 in situ for sale to those interested in the matter who may 

 care to apply for them. His address is 37, Broad Street, 

 Oxford. H. N. Mosei.EY 



NOTES 



M. I' 1 iTEUR read to the Academy of Sciences on Monday an 

 account of his experiments on rabies. He maintains that he has 

 twentj dogs which he has rendered insusceptible to the disease, 

 and which, with twenty ordinary dogs, lie i.s prepared 10 have 

 bitten by a number of dogs in a rabid state. A Commission has 

 been appointed by the French Government to test M. Pasteur's 

 conclusions, the immense importance of which, if established, 

 must be evident to every one. Eminent physiologists maintain, 

 however, thai M. Pasteur is far from having proved his position, 

 and that it would be rash to give any positive opinion upon the 

 subject until the experiment which lie suggests has been made. We 

 await the full report of M. Pasteur's paper before saying more upon 



