60 NOTES AND MEMORANDA. ['^TZal^JanTlC' 



direction. Opaque objects are seen with 4-lOtlis and l-4tli inch 

 objectives (from 200 to 500 diameters), brilliantly illuminated on a 

 black background. The appearance of diatoms is similar to that 

 obtained with the parabola, but the details of svu'face are shown with 

 a distinctness never before seen. Of how much utility this is to 

 prove, and what discoveries are to be made in the works of nature 

 with it, are among the problems that the microscopists are called on 

 to solve. 



Dr. Woodward's Article in No. XII. of this Journal. An 

 Explanation. — Some apology is due to Dr. Woodward for the 

 omission of the diagram from his paper, as jniblished in our last. The 

 omission was caused by inadvertence or forgetfulness on the part of 

 the Secretary, Mr. Jabez Hogg. On noticing that the printer had left 

 sjjace for a diagram we sent to Mr. Hogg — who had, of course (as 

 Col. Woodward's representative), compared the manuscript and 

 proof before sending it to us — to ask him whether there was a sketch 

 of a diagram for Dr. Woodward's paper. To this Mr. Hogg replied, 

 that he knew of nothing of the kind ! The only coui'se open to us, 

 therefore, was that expressed in our foot-note to Dr. Woodward's paper, 

 and it remains for Mr. Hogg to explain how he compared Dr. Wood- 

 ward's proof with the MS., and yet failed to see the diagram in the 

 latter. 



Professor Huxley's Classification of Animals. — A very severe 

 and long critique on this book appears in the ' American Naturalist ' 

 for December. 



A New Treatise on Microscopic Objects. — Mr. Van Voorst is 

 about to issue a very comprehensive treatise on Microscopic Objects. 

 The Author is Mr. J. H. Martin, Secretary to the Maidstone and 

 Mid-Kent Natural History Society. The first j)art was to have been 

 issued on the 1st of this mouth. Each part will contain eight plates and 

 eight pages of text- The whole number of figures will be 200, and we 

 cannot help thinking that Mr. Van Voorst will have to exert more than 

 his ordinary skill as a scientific publisher, if he contrives to include 

 the whole range of histology in these. The figui-es will be faithful 

 drawings of the structures as they appear when as nearly as possible 

 filling the ordinary field of the microscope. It is projjosed to com- 

 mence with the primary forms of Vegetable life, and to proceed on- 

 wards thi"ough the tissues to the woody structui-es of the Exogens and 

 Endogens, next descending to the Acrogens, and so passing to the 

 extreme limits of vegetable life, as the Desmideaj, &c. ; hence to the 

 lower forms of Animal life, the lufusoria, and on through the Eadiata 

 to the Insects, which will be di-awn and described in their various 

 orders, and the minute organs figured separately. In the concluding ' 

 Plates will be represented interesting and characteristic geological 

 structures, with some of the more curious forms and groupings of 

 crystals. The description of the objects will be brief, and, as far as 

 possible, void of technicalities ; and no attempt will be made to enter 

 into details relating to their physiological action. 



Blankley's revolving Mica-Selenite Stage. — This stage, which 



