jVA ture 



[April 



20, li 



Rotifera are well represented in Ireland, and Miss Glascott has 

 been induced to issue her list in the hope that it may lead other 

 observers to study the group. 



Dr. John Struthers contriiuites to the current number 

 of the Journal of Anatomy and Physiology an important paper 

 on the rudimentary hind-limb of a great fin-whale {Balcenoptera 

 tnusculus) in comparison with those of the humpback whale 

 and the Greenland right-whale. His object is to determine the 

 interpretation which should be given to the occurrence of a 

 part apparently so rudimentary as a thigh-bone of about the 

 size of a pigeon's egg in a great whale. He decides that the 

 presence of the bone in fin-whales cannot be accounted for 

 from the point of view of function, and that the bone must be 

 regarded only as "a vestige." In the course of his inquiry 

 Dr. Struthers has had occasion to note the need for caution in 

 the attempt to find a functional explanation of the presence 

 of rudimentary structures. "In endeavouring," he says, "to 

 assign uses to rudimentary structures, we have to keep in view 

 that such parts may in reality serve no purpose of functional 

 utility, maybe meaningless except as the products of decreasing 

 heredity or as the incidents of variability, and that the parts 

 attached to such structures may be but remnants, or may be 

 adaptations acquired amid the surrounding activities." 



The purification of water more especially for drinking pur- 

 poses has assumed quite a different character since the 

 introduction and application of the bacteriological methods now 

 in vogue. Novel processes have in consequence been devised, 

 whilst those already in use have received an altogether new 

 interpretation. In two recently published pa[)ers further con- 

 tributions are made to both these aspects of the subject. V. and 

 A. Babes, in " Ueber eiii Verfahren keimfreies Wasser zu 

 gewinnen" {Centralblatt fiir Bakteriologie, July 30, 1892), 

 describe a se ies of experiments which they have conducted on 

 the removal of micro-organisms in water by means of alum. 

 Some years ago Leeds made some investigations on this subject, 

 an 1 showed that by the addition of one-half grain of alum to 

 a gallon of water the number of microbes in fifteen drops was 

 leduced from 8100 to 80. This material has, moreover, been 

 employed for the purification of water on a large scale in 

 America, the amount used varying according to the water, from 

 one-half to six grains per gallon of water. lu the above paper 

 the authors record the use of very much larger quantities of 

 alum than Leeds, and in all cases after agitating the water with 

 this material, they obtained an absolutely sterile liquid, although 

 the water contained originally as many as 1200 microbes in 

 about twenty-five drops. The number of bacteria in the sedi- 

 ment of a water shaken up with alum was also investigated, and 

 was found to contain but a m re fraction of the organisms 

 originally present. In the second paper, " Rrinigung des 

 Wassers durch Sedimentirung " {Centralblatt fur Bakteriologie, 

 February 8, 1893), Percy Frankland details some further investi- 

 gations he has recently made on the purification of water by 

 sedimentation. This author conducted a series of experiments 

 some years ago on the removal of micro-organisms from water 

 by means of agitation wiih different solid particles, both in the 

 laboratory and as practically carried out during the softening of 

 water by means of lime in Clark's process. In the present 

 investigations attention is directed to the bacterial purification 

 which takes place during the storeage of water on the large 

 scale in reservoirs. The following experiment may be cited, 

 showing the nature of the results obtained : — The Thames water 

 before flowing into the reservoirs of one of the London water 

 companies contained 1437 microbes per c.c. (about 25 drops) ;on 

 passing out of the first reservoir there were 318 present ; whilst 

 after passing through the second reservoir only 177 were present 

 in the c.c. Both Frank and Schlatter, the former for the river 

 NO. 1225. VOL 47] 



Spree, and the latter for the river Limmat at Ziirich, have 

 pointed out the reduction in the nmnbar of bacteria which is 

 exhibited in the course of a river's flow, and the above results 

 show clearly how important a factor is sedimentation in this 

 process of purification. 



A FULL report of the sec in-1 session of the International Con" 

 gress of Experimental Psychology, held in London in 1892, has 

 been published by Messrs. Williams and Norgate. 



A LITTLE book which seems likely to be of good service to 

 young students of geometry has been published by Messrs. 

 M\cmillanand Co. It is called "Exercises in Euclid, Graduated 

 and Systematized," and is by Mr. William Weeks, lecturer on 

 geometry, St. Luke's Training College, Exeter. The examples 

 are grouped in sets, each set bearing upon, and serving to 

 i npress, some fundamental fact or principle which is stated in 

 liirger type at the head of it. Thus the object of the book is to 

 build up the pupil's knowledge, and to develop in him gradually 

 the power to grapple successfully with difficult deductions. 



Some remarkably intereiting illustrations of the zoological 

 results obtained by the naturalists on board II. M. Indian marine 

 surveying steamer Investigator are being published. They 

 consist of plates with brief explanations of the figures. We have 

 received Part I. of "Fishes," by A. Alcock, and Part I. of 

 " Crustaceans," by [. Wood-Mason. In the former there are 

 seven plates; in the latter, five. 



"A Dakota-E.N'GLISH DicrioxARv" has been published by 

 the U.S. Department of the Interior. It is an enlarged and 

 improved version of a work prepared by a missionary, the Rev. 

 S. R. Riggs, and published by the Smithsonian Institution in 

 1852. Mr. Riggs died in 1883, but had been able to get the 

 new edition of his dictionary ready for the press. The task of 

 editing his materials has been fulfilled by Mr. J. O. Dorsey, 

 who has made a special study of the Siouan language, including 

 the Dakota, since 1871. 



A NEW mode of preparing hyponitrous acid, IlaNjO^, 

 eminently suitable for demonstrating the existence of this 

 interesting lowest acid of nitrogen in the lecture room, is 

 described by Dr. Wilhelm Wislicenus in the current number of 

 the Berichte. It will doubtless be remembered that hyponitrous 

 acid was first prepared in the year 1871 by Divers, by reducing 

 nitrates with sodium amalgam. Zorn subsequently showed that 

 the molecular composition of the acid was most probably repre- 

 sented by the double formula HjN^-jOa. He prepared the ethyl 

 salt and found it to be a substance suiiable for a determination 

 of vapour density ; the numbers obtained upon making a series 

 of such vapour density determinations indicated that its 

 molecular composition was (CaHgJaN.jO^. Several years ago 

 Victor Meyer described an interesting reaction of hydroxylamine, 

 NHgOH. He showed that nitrous acid and hydroxylamine 

 mutually decompose each other with production of water and 

 nitrous oxide gas. NIIjOH + HNO^ = 2H2O + N._,0. It was 

 further shown that when concentrated solutions of hydroxylamine 

 sulphate and sodium nitrite are mixed a rise of temperature and 

 a violent evolution of nitrous oxide occur. Dr. Wislicenus 

 now shows that even very dilute solutions of sodium nitrite and 

 hydroxylaminehydrochloride although cooled by iceslowlyevolve 

 nitrous oxide, eventually suPferingcomiilete mutual decomposition. 

 The explanation of these reactions between hydroxylamine and 

 nitrous acid has hitherto been unknown. It is now shown to be 

 due to the fact that hyponitrous acid is produced as an unstable 

 intermediate product. 



NH2.OH+ NO. OH = HO.N:N. OH + HoO. 

 It is a well-known fact that hyponitrous acid readily breaks up 

 into nitrous oxide and water, hence the explanation of Victor 



