26 



SCIENCE- G OS SI P. 



result that spherical aberration is corrected in a 

 manner that is, so far as we are aware, only 

 equalled by the apochrornatic lenses. As a con- 

 sequence these objectives will stand unusually 

 high eyepiecing without giving a " rotten " 

 image. The lenses are under-corrected, and 

 require to be used with over-corrected oculars of 

 the ordinary or of the "Holoscopic" adjustable 

 type. A noticeable feature is the great diameter 

 of the back-lens. The price of the |-inch is £i 

 and of the 1-inch £2 5s. The former is con- 

 structed for either the short or long tube, but the 

 latter for the long tube only. 



Swift's New Portable Microscope. — Messrs. 

 Swift have sent for our examination an improved 

 form of their portable folding microscope, which 

 we noticed last September (ante, p. 118). The new 

 model is fitted with a sub-stage focussing adjust- 

 ment of the now familiar spiral-screw type, and 

 also with a removable mechanical stage. The 

 latter we illustrate herewith, and its mechanism 



will be at once apparent. The sides of the micro- 

 scope stage are provided with parallel grooves, into 

 which the mechanical stage fits, and in which it 

 runs vertically, the movements being dependent 

 upon friction instead of the usual rack and pinion ' 

 arrangements. It is effective, works smoothly, 

 cannot easily get out of order or wear loose, is 

 instantly attached or removed without the need of 

 any binding screws, and costs only fifty shillings. 

 Of the microscope itself we have previously spoken 

 highly, and we are not surprised to learn that it 

 has already met with a considerable sale, especially 

 for army work and in connection with the study 

 of tropical medicine, for which it is well fitted by 

 its compactness. The addition of the focussing 

 sub-stage, added to its excellent design and work- 

 manship, makes this instrument suitable for almost 

 all classes of serious work. The cost of the latter 

 adjustment is 20s., making the total cost of the 

 microscope, in leather cases, £6, or, with Abbe 

 condenser, iris diaphragm, and blue glass and 

 carrier, £l 10s. The mechanical stage is, of course, 

 an extra. 



MEETINGS OF MICROSCOPICAL SOCIETIES. 



Royal Microscopical Society, 20 Hanover Square. 

 June 19, 8 p.m. 



Quekett Microscopical Club, 20 Hanover Square. 

 June 7, 21, 8 p.m. June 15, * Surrey Commercial 

 Docks. 



[For further articles on Microscopic subjects see 

 pp. 1, 4, 7, 8, and 11, in this number. — Ed. Micro- 

 scopy, S.-G.] 



EXTRACTS FROM POSTAL MICROSCOPICAL 

 SOCIETY'S NOTEBOOKS. 



[Beyond necessary editorial revision these ex^ 

 tracts are printed as written by the various 

 members. — Ed. Microscopy, S.-G.] 



[The following notes by Mr. Lett, though intended 

 to be descriptive only of his own slides as circu- 

 lated in the P. M.S., are sufficiently suggestive to 

 warrant their reproduction. The study of micro - 

 fungi is most fascinating, and will well repay the 

 attention of any of our readers who may not yet 

 have devoted time to it. Most of the fungi alluded 

 to below are those which make their appearance 

 upon rotting wood or decaying vegetation, but 

 perhaps an even more interesting occupation is to 

 search the leaves and stems of living plants. 

 Especially does this apply to the heteroecious 

 fungi — those which pass a part of their lives upon 

 one plant and the remainder upon another and 

 entirely different plant. The common " rust " of 

 corn, Puecinia graminis, forms an instance of this 

 remarkable alternation of generations, passing part 

 of its life-cycle on the haulms of grapes and part 

 on the leaves of the barberry, both hosts being" 

 absolutely necessary for its development. Though 

 this fact is now well known, it was formerly so 

 little realised that the fungus, owing to its widely 

 different appearance, received different names 

 according to its period of development, the bar- 

 berry stage being previously generally known as 

 Aecidium berheridis. The process itself is one 

 that can be traced by any observer who will take 

 the trouble to place the spores upon the different 

 host-plants. It is of course necessary to make sure 

 that the spores have not already germinated. We are 

 tempted to give a brief sketch of the life-history of 

 one of these micro-fungi, such as Puecinia gram inis, 

 above mentioned, if only to explain to those un- 

 familiar with them the meaning of several of. the 

 terms used in the following notes ; but limitations 

 of space necessitate our referring our readers to 

 the various botanical text-books. With regard to- 

 collecting we may say that, whilst experience 

 saves both time and trouble, the searcher will soon 

 learn to recognise micro-fungi. It may be a dis- 

 coloured spot upon a leaf, or a red, yellow, black, 

 or brown patch ; it may be an appearance like 

 spores on the backs of ferns, or it may be merely 

 a distortion of the stem. A close examination will 

 generally be repaid. In gardens, fields and ditches,, 

 on railways, and on the borders of woods, micro- 

 fungi are to be found ; the damper the situation 

 the better generally ; so that there are few country 

 walks that would not readily yield a dozen and 

 more specimens. This is true throughout the 

 year, though less so in winter. Generally speak- 

 ing, it may be said that it is better to thoroughly 

 examine a comparatively small portion of ground 

 than to endeavour to cover a wide area. Most of 

 the species will be found on the under-side of 

 leaves, but there is great diversity in their 

 appearance. We need not add to the methods of 

 mounting mentioned below, but would urge 

 that the following out of life-histories, or even 

 careful examination and study under the micro- 

 scope, is of more importance than the mere 

 collecting of specimens and ascertaining their 

 species. The spores themselves can be sown in 

 water in an excavated cell or an ordinary slide, 

 the slide being of course placed under a small 



