SCIENCE- GOSSIP. 



55 



CONDUCTED BY P. SHILLINGTON SCALES, F.R.M.S. 



Eoyal Microscopical Society. — May 15th, Dr. 

 R. Braithwaite, F.R.S., Vice-President, in the chair. 

 Dr. Hebb read the reply from His Majesty the 

 King in acknowledgment of the Address which 

 was sent to him from the meeting- on February 20th. 

 A paper by Mr. Fortescue W. Millett, being part xi. 

 of his report on the recent foraminifera of the 

 Malay Archipelago, was taken as read. Notice 

 was given that on June 19th, at 7.30 p.m., there 

 would be a special meeting of the Fellows for the 

 purpose of making certain alterations in the bye- 

 laws. The Secretary announced that at the next 

 meeting of the Society there would be a paper on 

 the "Aperture Theory of the Microscope," by Mr. 

 J. W, Gordon. Mr. Beck asked any who possessed 

 Abbe's diffraction apparatus to lend them for use in 

 illustrating the subject of Mr. Gordon's paper. Mr. 

 Gordon would endeavour to show that the effects 

 described by Professor Abbe, and relied upon by 

 him to prove his diffraction theory, were produced, 

 not by the object on the stage, but by the dia- 

 phragm over the object-glass ; to demonstrate 

 this satisfactorily, Mr. Gordon would require the 

 use of several sets of diffraction apparatus besides 

 those at his present disposal. The Chairman drew 

 attention to a large number of objects illustrating 

 pond life, which were exhibited under about thirty- 

 five microscopes by members of the Quekett Micro- 

 scopical Club and by Fellows of the Society. 



"Quekett Microscopical Club Journal." — 

 The April issue of this journal has duly reached 

 us. It contains the President's address to the 

 club, which refers to fungi, mainly the larger 

 edible and poisonous species. Amongst papers 

 read before the club during the preceding six 

 months, and now printed in extenso, we may 

 mention an interesting reference, by Mr. A. A. 

 Merlin, to the resolution of Ampltipleura pellucida 

 into the well-known transverse striations, which he 

 claims to have effected with a Zeiss 4-mm. dry 

 apochromatic objective of N.A. - 95--96, a 27 com- 

 pensating eyepiece, and a § solid axial cone of 

 illumination from an apochromatic oil-immersion 

 condenser. Not only was the resolution of a 

 diatom mounted in realgar effected, but also of 

 others mounted in balsam and dry. The point at 

 issue lies in the fact that such resolution would 

 very greatly exceed the theoretical power of reso- 

 lution of a lens of such N.A. as the one referred 

 to, used without oblique light, calculated in accord- 

 ance with the generally accepted theory and 

 formula of Professor Abbe. The paper naturally 

 called forth an interesting discussion. Dr. Spitta, 

 who read the paper in the absence of the author, 

 explained at length the reasons why Mr. Merlin's 

 statement could not be accepted, and suggested 

 that the diatom was coarsely marked — a point 

 which is so obvious that we can scarcely think it 

 would have been overlooked by Mr. Merlin, who 



could readily have counted the number of striations 

 with a micrometer eyepiece. Mr. E. M. Nelson, 

 however, called attention to the fact that the 

 Abbe diffraction theory did not fit in with all the 

 observed phenomena bearing upon that branch of 

 microscopy, and added that the large solid cone 

 had a greater resolving power than was generally 

 supposed. Not only is this, according to our ex- 

 perience, correct, but the resulting image is in all 

 probability an infinitely more trustworthy repre- 

 sentation of the actual structure than that given 

 by oblique illumination. We hope Mr. Merlin will 

 go further with the matter, will satisfy himself as 

 to the exact number of striations upon the diatom 

 examined by him, and will photograph it under 

 the conditions mentioned. Some modification 

 of Professor Abbe's formula may yet be re- 

 quired. Mr. Rousselet describes the difference 

 between two allied rotifers, Asplanchna inter- 

 media and A. brightwelli ; Mr. Julius Rheinberg 

 endeavours to answer Mr. Nelson's query as to 

 the colour exhibited by the diatom Actinocychis 

 ralfsii(see Science-Gossip, vol. vii., p. 282) ; Messrs. 

 F. R. Dixon-Nutall and M. F. Dunlop each describe 

 a new rotifer ; Mr. G. W. Kirkaldy contributes an 

 interesting paper on the stridulating organs of 

 water-bugs ; Mr. C. D. Soar describes a hitherto 

 unrecorded hydrachnid from a tarn on Snowdon ; 

 and Mr. D. J. Scourfield investigates the mode of 

 formation of the ephippium of Bosmina, or corre- 

 sponding protective covering of the egg of this 

 genus. The last named, in addition to his editorial 

 duties, contributes to the journal several excellent 

 notices of recent books. The annual report shows 

 a membership of 340, which we hope will be fur- 

 ther increased. By the courteous co-operation of 

 the Honorary Secretary, when the club resumes its 

 monthly meetings we propose to give brief ac- 

 counts of these each month, as we have for some 

 time done of the Royal Microscopical Society's 

 meetings, not only for the convenience of our 

 readers, but hoping thereby to stimulate interest 

 in the societies themselves. Their work deserves 

 the support of all microscopists, whether amateur 

 or professional. 



Stridulating Organs in Beetles.— C. J. 

 Gahan in " Trans. Entom. Soc," London, 1900, 

 pp. 433-52, comments upon Schrodte's discovery of 

 well-developed stridulating organs in the larvae of 

 several genera of beetles, and on the fact that the 

 structures are generally alike in both sexes of 

 adults, though with some notable exceptions. He 

 describes the stridulating organs on the head, on 

 the prothorax and front legs, on the mesothorax 

 and middle legs, and on the hind legs, elytra, and 

 abdomen. 



Rotatoria of the United States. — The 

 "Journal of the R.M.S." for April last refers to an 

 interesting list, with critical notes, by Mr. H. S. 

 Jennings, which appears in the " U.S. Fish Com- 

 mission Bulletin " for 1899 (1900), pp. 67-104. It 

 gives all the species of rotifers, 246 in number, 

 hitherto found in the United States, with special 

 reference to those discovered by the author in the 

 great lakes. Two species, Notops pelagieus and 

 Pleurotrocha parasitica, are described as new. As 

 a general result of his investigation the author 

 formulates the conclusion that the Rotatoria are 

 practically cosmopolitan, any species occurring 

 wherever the conditions necessary to its existence 

 are to be found. In stagnant swamps all over the 



