SCIENCE- G OSSIP. 



2 45 



objective of N.A. 1.3, for instance, being priced 

 at $120= £24, and the corresponding- objective 

 of N.A. 1.4 costing $1(50 = £32. Zeiss' juices for 

 similar lenses arc respectively Jl\"> and £20. The 

 stands are built entirely upon the Continental 

 model, which is closely adhered to, not only in the 

 horseshoe stand and in the fine adjustment, but 

 also in the later Continental forms of sub-stage 

 arrangements. The list of accessories seems to 

 contain everything that the heart of a microscopist 

 could desire, and sundry apparatus and accessories 

 for mounting are mentioned and illustrated in 

 unusual detail. 



Answers to Correspondents. — H. O. W., Bud- 

 leigh Salterton. The ordinary collodion of the 

 B.P. would serve your purpose. Flexile collodion 

 is used medically and contains castor oil. We 

 would recommend, however, Schering's Colloidin, 

 which is largely used by microscopists for section 

 cutting. It can be obtained in chips or solution, 

 A bottle containing 50 grams of the latter can be 

 obtained from C Baker for Is. 3d. Beech-tar 

 creosote is to be preferred, especially for clearing 

 colloidin sections, but coal-tar creosote would do 

 equally well, provided it is really white. We shall 

 be glad to give you any further assistance in our 

 power. — F. S. S. 



EXTRACTS FROM POSTAL MICROSCOPICAL 

 SOCIETY'S NOTE-BOOKS. 



[Beyond necessary editorial revision, these notes 

 are printed as written by the various members, 

 without alteration or amendment. Correspondence 

 on these notes will lie welcomed. 

 These extracts were commenced 

 in the September number at page 

 119.— Ed. Microscopy, S.-G.] 



Notes by W. T. McGhie. 



Bacteria in Water. — A few 

 weeks ago I noticed that a glass 

 ornament on the sideboard in 

 my dining-room contained some 

 flowers in rather cloudy water, 

 and guessing that carelessness had 

 led to the water being left too long 

 I examined a drop of it for infu- 

 soria under a moderately high 

 power. I was surprised to find 

 that the water was absolutely thick 

 with every kind of sehizomycetes, 

 micrococci, bacteria, bacilli, spi- 

 rillae, vibriones, and leptothrix 

 forms, besides a few paramoecia, 

 monads, etc. The spirilla forms 

 were unusually plentiful and ac- 

 tive, and several zoogioean masses 

 of bacteria were noticeable. I 

 mounted some slides from the 

 liquid, of which the accompany- 

 ing is one. The microbes are 

 stained with logwood on the 

 cover-glass and mounted in bal- 

 sam. They will afford a test for 

 the excellence of the objectives, 

 condensers, and tine adjustments 

 of our members' instruments. The 

 vibriones have taken the stain best, the other forms 

 indifferently. By the way, though balsam-mounting- 

 is always recommended in the text-books, bacteria 

 show much better mounted dry on the cover-glass. 



Ai Least, I find it so. A good quarter-inch ob- 

 jective, which will bear a high amplification, 

 will show well-stained slides surprisingly well. 

 Scales of Clothes-hiotli. — This slide may be con- 

 sidered a trivial one to send round ; but 

 though the scales are not rare, they exhibit much 

 beauty of marking in the way of striae and villi 

 when examined under moderately high powers, 

 besides making a charming dark-ground slide 

 under finch or 1-inch objectives. I have in- 

 cluded the slide, however, principally because I 



Fig. 1. Development of insect hairs and scales. 



think these scales exhibit better than any others 

 the evolution of the insect scale from the simple 

 hair, or rather the probable lines on which it took 

 place. (See fig. 1.) I should much have liked to 

 illustrate this by a picked slide, but could not do 

 so, as I had not the requisite steadiness of hand. 

 On the spread slide, however, will be found plenty 

 of specimens in all the stages of change. The 



Fig. 



Lamellae of antennae 



piece of wing on the same slide shows well the 

 distribution of the scales : flattest on the centre of 

 the membrane, and shading off into bundles on 

 the edges. In the nervures a crooked system of 



