July 21, 1898] 



NATURE 



275 



their abode in the pitcher are, like the insects that ven- 

 ture in, unable to get out again on account of the oppo- 

 sition to exit offered by the slipperiness of the walls of 

 the conductive area. If this be so, they would be com- 

 pelled, in case of attack, to seek safety in the lower parts 

 of the pitcher ; and while those too timid to take the 

 plunge, or too weak to withstand the immersion, would 

 be captured or destroyed, their instinctively bolder or 

 physically hardier companions would be saved to transmit 

 their characteristics ; and so by a process of elimination 

 and selection the instinct would be gradually brought to 

 the state of perfection Mr. Everett has described. 



Lastly, if it be wondered by what means the spider is 

 able to resist the action of the fluid, and to regain its 

 position of security in the upper part of the pitcher, it 

 must be remembered, in the first place, that a great many 

 spiders, as well as many insects, can be immersed in 

 water and other liquids, and withdrawn in a perfectly 

 dry state ; and in the second place, that almost all 

 spiders when dropping from their webs or leaping after 

 prey, ensure a safe return to the spot they have left by 

 letting out a drag- line of silk, which passes from the 

 spinning mammilkc to the point of departure. A silken 

 thread of this description would enable M. nepettthicola 

 to climb out of the digestive fluid which retains the cap- 

 tured insects ; while the nature of the integument and 

 of its hairy clothing would prevent the penetration of 

 the fluid during the short time that the spider remains 

 beneath it. R. I. PococK. 



FERDINAND COHN. 



C\^ June 25 last the career of one of the great botanists 

 ^-^ of the latter half of this century was brought to a 

 close. During the span of a long life of seventy years 

 Ferdinand Cohn has devoted his best energies to the 

 advancement of botany, and the list of his papers in the 

 " Royal Society Catalogue of Scientific Papers " bears 

 witness to an unwearied devotion to his life work. 



In his earlier years Cohn was amongst the foremost of 

 those who were engaged on investigations into plant life 

 and animal cells, and to the last it was the lowlier members 

 of the vegetable kingdom that attracted his chief atten- 

 tion. But it was ever the striving after a deeper insight 

 into the nature of the living organism that stands out as 

 the keynote of his numerous researches, and the grasp 

 which he possessed of the current problems is seen in 

 one of his earlier papers on Protococciis pluvialis. In 

 this memoir he brought forward cogent arguments in 

 support of his view that the Protoplasm, recognised a few 

 years before by Von .\Iohl as the essential living substance 

 of plants, was identical with Sarcode, first described for 

 animalsbyDujardin ; andCohn's arguments were the more 

 worthy of attention inasmuch as he was already familiar 

 with, and was writing about, Infusoria. It is singular 

 that Cohn's claims to have first established this great 

 generalisation should have been so obscured by the work 

 of Briicke and Max Schultze, since the memoirs of these 

 investigators were published several years after Cohn's 

 paper which appeared in 1850, and was shortly afterwards 

 translated into English under the auspices of the Ray 

 Society. 



In those early years, from 1847 and onwards, new con- 

 tributions to science flowed rapidly from the pen of the 

 hard-working man. His papers on Pilodolus, Empusa, 

 Sphccroplea and on Volvox are well known. Some of 

 them were at once recognised as of prime importance, 

 and were translated into English and French. 



But Cohn's interest was by no means restricted to these 

 channels, for several of his early works deal more 

 especially vvith physiological problems. The injuries 

 caused by lightning and the problems of disease also 

 engaged his attention, and it was perhaps chiefly in con- 



NO. 1499, VOL. 58] 



nection with the latter class of questions that his later 

 investigations were pursued.. The importance of his 

 work on Bacteria was long ago recognised, and the 

 attitude which, in opposition to Nageli, he maintained 

 towards the pleomorphism of these organisms has turned 

 out to be substantially the correct one. Naturally, how- 

 ever, it was not to be expected that genera distinguished 

 at this (relatively) early period would prove to be natural 

 ones, but the existence of independent species, alsa 

 recognised by De Bary, is now everywhere admitted. 



In addition to his work as a teacher and an investi- 

 gator, Cohn's " Beitrage zur Wissenschaftliche Botanik " 

 will always serve to keep his memory green in the minds 

 of botanists. These volumes contain a large number of 

 important papers, manyof which were the direct outcome 

 of his personal influence. 



The " Kryptogamen-flora von Schlesien " also testifies 

 to his editorial energy, and he was himself one of the 

 most active members of the Schlesische Gesellschaft zu 

 Breslau, and many of his papers are to be found in the 

 records of this Society, to which also in his later years he 

 contributed many valuable and suggestive reviews of 

 current work ; and these will always prove of permanent 

 value to the historian of this period. 



Cohn was a foreign member of the Royal and Linnean 

 Societies of London, and the gold medal of the latter 

 Society was awarded to him in 1895. Few men have 

 more justly earned the" respect of their fellows than he, 

 and all might well profit by the example of his industrious- 

 career. He is gone, but his work remains as a lasting 

 monument to his fame : — 



"Sicut fortis equus, spatio qui saepe supremo 

 Vicit Olympia, nunc senio confectu' quiescit." 



J. B. Farmer. 



NOTES. 



The French Association for the Advancement of Science will 

 this year hold its meeting at Nantes, from August 4 to 11. 



The annual general meeting of the Victoria Institute was 

 held on Monday afternoon last, when Sir George Stokes 

 delivered his presidential address. The subject of the address 

 was "The Perception of Colour. " 



The Council of the British Medical Association resolved at 

 its last meeting to found as a memorial of the late Mr. Ernest 

 Hart a scholarship to be called "The Ernest Hart Memorial 

 Scholarship for Preventive Medicine." It was felt that no 

 more fitting means could be found to commemorate at once Mr. 

 Hart's great services to the British Medical Association and to 

 the advancement of the study of preventive medicine. The 

 scholarship, which will be of the annual value of 200/., will be 

 tenable for two years. 



At the recent Council meeting of the Iron and Steel In- 

 stitute, Prof. Roberts- Austen, C.B., F.R.S., was elected to 

 succeed Mr, Martin Dowlais as president of the Institute. 



Sir Martin Conway has started for Bolivia. It is his in- 

 tention to explore the high group of the Andes containing the 

 peaks lUimani and lUampu (or Sorate). He is accompanied by 

 the Alpine guides Antoine Maquignaz and Louis Pellissier, who 

 made the first ascent of Mount St. Elias in Alaska last year 

 with the Duke of Abruzzi. 



Prof. Max Weber, the well-known zoologist of the 

 University of Amsterdam, will leave Europe in October next, 

 for Sourabaya, Java, to take command of a scientific expedition,, 

 projected by the Society for the Biological Investigation of the 

 Netherlands Colonies, for the zoological, botanical and oceano- 

 graphical exploration of the seas of the Indian Archipelago. The 

 course of the expedition, which will last about a year, is divided 

 into two sections. The first, starting from Sourabaya, will pass 



