542 



NA TORE 



[AikiL 6, 1899 



Although the muscle is unstriped, it acts quicker than the 

 iris. Accommodation is paralysed by atropin in fishes, 

 hut not in cephalopoda. 



Even deep-sea fishes, living at a depth where the light 

 does not affect a photographic plate exposed for a whole 

 day, possess an accommodating apparatus. 



.\mphibians that accommodate, usually do so for near 

 objects ; not, however, like most other animals, by alter- 

 ing the curvature of the lens, but by increasing the dis- 

 tance between retina and lens through contraction of the 

 ciliary muscle. This muscle is unstriped, and the rate of 

 accommodation is slow. 



.Accommodation is altogether absent in frogs. In 

 these, too, the curvature of the cornea is so great, that 

 in water the hypermetropia, for which no correction 

 exists, is as high as twenty-five diopters. Toads, which 

 can more easily than frogs catch worms and near still 

 objects, possess a slight power of accommodation. 



Serpents accommodate in a similar manner, but 

 quicker, because instead of a ciliary muscle, which is 

 generally absent, they possess a striped circular muscle 

 inserted in the attachment of the iris. Contraction 

 thereof presses forward the lens, without altering its 

 curvature, towards the cornea. This mechanism of 

 accommodation increases the pressure in the posterior 

 chamber, and is consequently destroyed by opening the 

 latter. 



.•Accommodation is in all such cases effected by 

 relaxation, as originally asserted by Helmholtz, not by 

 increased tension, of the suspensory structures of the lens. 

 By this action it becomes more spherical and of shorter 

 focus. This change can be seen to have taken place in 

 some animals even after removal of the supporting 

 ligaments. 



Of Amphibians many have a range of accommodation 

 from ten to fifteen diopters. In animals of nocturnal 

 habits accommodation is least developed. It is in birds 

 that it reaches its highest perfection. Crampton's muscle 

 is here the chief factor in producing relaxation, the 

 inner layer of the cornea being pulled back, and not the 

 parts behind the ciliary region forward, as in mammals, 

 where the choroid is pulled forward. 



It has been supposed that tightening the zonula caused 

 increased pressure in the vitreous, and thereby increased 

 the curvature of the front surface of the lens. -Since, 

 however, electrical stimulation of the enucleated cat- or 

 monkey-eye produces nearly identical results, whether 

 the bulb be intact or cut into (in the latter case there can 

 be no increased pressure in the vitreous), this theory can 

 hardly be correct. 



iManhas the greatest range of accommodation. After 

 him come monkeys (up to ten diopters), then cats and 

 other beasts of prey, and seals. Larger-eyed animals 

 accommodate at a greater distance, but through a lesser 

 range than man. Horses can also accommodate. But 

 many animals, et;. dog, use their noses rather than their 

 eyes to examine near objects. 



The anatomical investigations of Hess and Heine have 

 confirmed most of these ophthalmosopic and experimental 

 results. 



Thus the two historical inventions of Helmholtz, the 

 ophthalmometer and the ophthalmoscope, are invaluable 

 not (inly to ophthalmology, but also to comparative 

 physiology. 



NOTES. 

 Tun fifs' "^f 'he two annual soirees of ihi; Royal Society will 

 be held on Wednesday, May 3. This is the soiree to which 

 gentlurtoen onlv are inviled. 



Tin; Dc|)uiy-Maslcr of the Trinity House, with a committee 

 of Elder brethren, accompanied by Lord Rayleigh, their 

 scientific adviser, and Captain the Hon. 1'. C. 1'. N'erekcr, of the 

 KO. 1536, VOL. 59] 



Board of Trade, arranged to leave London yesterday for Dover, 

 with the object of making an official inspection of the wireless 

 telegraphy system as experimentally in operation between the 

 South Foreland lighthouse and the East Goodwin light vessel. 



Reuter's correspondent at Buenos Ayres reports that de- 

 spatches received from Punta Arenas, Patagonia, announce the 

 arrival there of the Belgi(a with the members of the Belgian 

 .Antarctic Expedition, under the command of Lieutenant de 

 ('•erlache. The Bclgina is said to have remained fast in the ice 

 for two months. 



LoRU Rayleigh and Prof. G. H. Daiwin have been elected 

 honorary members of the New York Academy of Sciences. 



Dr. T. J. J. See, who was recently appointed professor of 

 mathematics in the U.S. Naval Observatory, has been nominated 

 as chief of the American Nautical Almanac Office. 



Prof. Mii.ne-Edw.^rhs, director of the Paris Natura) 

 History Museum, and president of the Geographical Society, 

 has received the Grand Cross of the Swedish Order of the Polar 

 Star from King Oscar II. 



Mr. J. Stanley G.^riuner, Balfour student of the Univer- 

 sity of Cambridge, and Mr. L. Borradaile have gone to the 

 Island of Minikoi, situated between the Maldive and Laccadive 

 Islands, to study the formation of coral reefs with special refer- 

 ence to the depth at which the reef-building c<ual organisms live, 

 the food of the coral polyps, the influence of currents upon coral 

 formations and upon the distribution of life near them, and the 

 inter-relationship existing between the various organisms which 

 occur on a coral reef. It is also proposed to survey the Maldive 

 Islands with a view to obtaining information as to their mode 

 of formation. Mr. C. F. Cooper will join the expedition during 

 the summer. 



Sir John Llhuock, in a letter to Monday's Times on the 

 Government Telephone Bill, draws attention to a point that is 

 often lost sight of. He points out that if the telephone becomes 

 national properly, not only will the State lose money, but " the 

 results as regards the progress of applied science will, in my 

 judgment, be even more disastrous. Those who have hitherto 

 devoted thought and time, energy and capital, to apply the re- 

 sults of scientific discovery to practical purposes are now told, 

 that while, of course, if their enterprise does not jxiy, they must 

 bear the loss, on the other hand, if it succeeds, Government will 

 pass an Act of Parliament to deprive them of any advantage." 

 In support of this opinion he quotes the late Mr. Varley as 

 follows : — " The introduction of protectionism in so important an 

 industry as telcgrai>hy has given the postal executive a grip hold 

 of applied electricity, and has enabled them to crush practically 

 out of existence pioneers in telegraphy and applied electricity. 

 English telegraph enterprise no longer exists, and America, 

 which twenty years ago was electrically in the rear of this 

 country, is now England's teacher. At the present time not 

 only does she take premier rank in dynamo-electric developments, 

 but practically all the telegraphic .advances which have been 

 made since the passage of the Telegraph .-Act have originated 

 from .American genius." . . . " The sole object I have in view 

 in writing is to bring home to the British public, if I can, the evil 

 consequences of the un-English retrograde policy of converting 

 applied science into a Government trading monopoly." This 

 point .should engage the attention of the Society of Telegraph 

 Engineers. 



A FEW facts with regard to irrigation in India were men- 

 tioned by Lord Cur?on on Monday, in replying lo an address of 

 welcome from ilie people of Lyallpur, a new town founded as 

 a result of the Clien;ib irrigation scheme. The Viceroy pointed 



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