112 



HARD IV I CKE 'S S CIENCE - G O SSIP. 



should be afterwards 'well washed with distilled water 

 before adding spirit. Objects, such as some parts of 

 insects, which are not transparent, need, as usual 

 previous maceration in potash solution. Benzole 

 would, doubtless, do equally well as ether, but I 

 have hitherto only used the latter. 



This method is not applicable to all objects ; 

 those containing, like the water-lily, an excessive 

 amount of water shrink too much, and must be 

 mounted in fluids. If it be desired to stain the 

 specimens, this is best done by adding the dye to the 

 methylated spirit. 



I do not claim this as a new method, but, as I 

 know many workers who have not heard of it, I 

 thought that such might care to try so expeditious, 

 easy, and certain a method. A. W. Stokes. 



Laboratory, Guys Hospital, S.E. 



MICROSCOPY, 



A New Immersion Object-glass. — At the last 

 Meeting of the Royal Microscopical Society, Mr. 

 J. H. Stephenson read a paper on this subject, in 

 which he described a new immersion object-glass 

 which he had designed to obviate the difficulty often 

 experienced in the accurate arrangement of the ad- 

 justing collars of high-angled objectives. This glass 

 had a focal distance of 1-9, and a balsam angle of 

 113 . It was stated to bear very deep eye-pieces, 

 and to have a very flat field. The great difficulty of 

 obtaining an "immersion" fluid having the same 

 refracting index as crown glass has at length been 

 overcome by the adoption of oil of cedar-wood, 

 diluted with 1*5 parts of oil of fennel-seed. 



Marine Amceba. — Dr. Entz states that species of 

 Amoeba have been found in sea as well as fresh water. 

 At Cuxhaven he found two species, A. Umax and 

 A. radiosa, very abundantly. He regards A. marina 

 as probably identical with A. radiosa, and possibly 

 also Ilaeckel's Protamtzba polypodia. 



"A New Field for tjie Microscope." — Under 

 this title, Mr. W. Saville Kent, F.L.S., has a pro- 

 fusely illustrated article in the April number of the 

 Popular Science Review. It describes the life-history 

 of a new group of flagellate monads, which require 

 a very high power to determine ; and the writer very 

 properly remarks that the new and high class magni- 

 fying powers, often only used to resolve dots or striae 

 on a diatom, or to solve a question of angular aper- 

 ture, might very usefully be employed in following 

 out the details of the life-histories of these most 

 interesting organisms. The article is of a most inter- 

 esting character throughout. 



Fossil Diatomace.e, &c— Some months ago I 

 received a piece of cement-stone from the island of 

 Fur, coast of Denmark. It is a poor variety of lime- 

 stone, and if a portion be dissolved in acid, the residue, 



when examined, is seen to consist of interesting marine 

 forms of diatomacere, chiefly species of Triceratiu/n, 

 I believe, possibly Amphitetras, also a few Cosciuo- 

 disci, and a great many small Polycystinoj, and Acti- 

 niscea. Is this stone generally known to microscopists ? 

 I have not been able co get any information concerning 

 it. Dr. Carpenter mentions Triceratium occurring 

 in a fossil state only in the Bermuda and Richmond 

 earth. — Will. Paterson. 



Diatomaceous Deposits near Richmond. — 

 I send herewith specimens of prepared diatoms, from 

 parts of the Richmond and Petersburg fields, lately 

 discovered by me. The Petersburg slide shows several 

 varieties of Coscinodiscus, Actinocyclus, Actinoptycluts, 

 Plcurosigma, and Euphodiscus. There are many 

 specimens of Triceratium on it, the most character- 

 istic being perhaps T. spinosum; B. rhombus is also 

 plentiful. The transparent character of most of these 

 diatoms, and the fact of finding many forms in this 

 deposit, common in fresh water, would indicate that 

 this part of our diatomaceous stratum may have been 

 laid down near the mouth of some great river of 

 later tertiary times. The Richmond slide shows most 

 of the rare forms of that deposit in greater abundance 

 than I have ever seen before, while it contains com- 

 paratively few of the Orthosira marina, which makes 

 the larger portion of the deposit from other parts of 

 the Richmond field. A Navicula with curious 

 beading on the connecting zone, and very fine stria- 

 tion, is shown in tolerable abundance, from four to six 

 or more on each slide. This particular form, Prof. 

 H. L. Smith thinks new, and it is a very good test 

 for a I -8th or i-ioth objective, which should resolve 

 it into squares with oblique light. The areolations 

 on the larger Coscinodisci can be seen with a good 

 simple triplet, while to show the markings on some 

 of the Rhizosolenia is a test for the very best high 

 powers. The two Richmond Plcurosigmas Virginica 

 and angulatum, are also plentiful, and as the striation 

 on these is uniform, so far as my observation goes, 

 this slide makes one of the best general tests to be 

 had, furnishing an accurate measure for the com- 

 parison of objectives, of nature's own ruling, perhaps 

 superior to any artificial lines made. — C.'L. Peticolas, 

 Richd., Fa. 



Living Microscopic Organisms. — It is with 

 great pleasure that we draw the attention of our 

 microscopical readers to the agency started by Mr. 

 Thomas Bolton, whose advertisement has several 

 times appeared in our columns. For a trifling sum, 

 Mr. Bolton sends forth living organisms of Spougi/la, 

 Hydra, Actino-sp/icerium, &c. It is some time since 

 we had more sincere pleasure in recommending what 

 our microscopical readers will agree with us in affirm- 

 ing is a genuine and praiseworthy undertaking. 



An Apology for Diatomaniacs. — Professor 

 J. E. Smith, in an address delivered before the 



