262 PROGRESS OF MICROSCOriCAL SCIENCE. 



observation in tlie work under notice. The plate which accompanies 

 the book is certainly, so far as we can see, opposed to the theory 

 laid down in the volume. Still, our readers will, we trust, judge the 

 book on its own merits. 



PROGRESS OF MICROSCOPICAL SCIENCE. 



Uniformity of Nomenclature in Objectives. — On this subject Dr. E. 

 H. Ward has a paper in the ' American Naturalist ' for March, which 

 is of interest, and which we shall probably reproduce in a future 

 number of this Journal. He thinks that the following questions still 

 remain open: — Should the standard one-inch objective be characterized 

 by magnifying ten diameters as used in the compound microscope, or 

 should it be compared to a simple lens of actually measured focus or 

 foci ? Should the objective be named by its equivalent focal length, 

 or by its amplifying power, or both ? Should our standard distance 

 of measurement be changed from ten inches [254 mm.] to nine and 

 five-sixths inches [250 mm.] ? From what point in the objective shall 

 the distance to the scale be measured ? At what point of screw-collar 

 adjustment shall the objective be placed for rating its angular apertm-e 

 and amplifying power? Should the name ocular be substituted for 

 " eye-piece " in general use ? 



Micro -inlwtography. — Mr. Charles Stodder has a semi-popular 

 paper on this subject in the ' Boston Journal of Chemistry.' It 

 seems, says Mr. Stodder, that the history and advantages of micro- 

 scopical photography are well given, though no reference is made to 

 the corresponding disadvantages, such as the unequal applicability of 

 the process to objects of different colours, and the necessity of repre- 

 senting a single focal plane or section of the object, while the different 

 varieties of delineation by hand-work enable the artist, if sufficiently 

 expert to know what he sees, and sufficiently candid to draw what he 

 sees and not what he thinks he ought to see, to reconstruct to some 

 extent the object, and represent at a single view the knowledge 

 gained by many slight changes of focus. Unfortunately for their 

 value as tests in this case, the so-called test-objects seem to be par- 

 ticularly suitable for photographic illustration. Of the Woodward 

 photographs familiar to the writer, those of the test-objects are 

 (probably necessarily) more faultless than those of the tissues, and 

 are therefore tests of the corrections of the objectives and of the 

 perfection of the illumination rather than of the general applicability 

 of the photographic process. Of this latter question, but little under- 

 stood as yet, the researches of Dr. Woodward and others give promise 

 of an early solution. 



Tlie Structure of the Bloom or Wax of Plants. — Professor De Bary's 

 paper on this subject in the Botanical Zeitung is thus abstracted 



