ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 105 



The adjustment of the apparatus is very simple, If, for example, 

 one wishes to use light of 280 /x /a it is only necessary to set the drum 

 indicator at 280 and then to make the corresponding corrections on the 

 adjustable objectives Oj and Oo. 



C4) Pliotomicrogrraphy. 



Eder, J. M. — Separat-Abdruck aus Jahrbuch fiir Photographie und Keproduk- 

 tionstechnik fiir das Jahr 1912. 



[The author summarizes with his usual thoroughness the more important 

 advances in microphotography and projection.] 



HaUe : W. Knapp, 12 pp. (L fig.). 



C5) Microscopical Optics and Manipulation. 



Photolysis of various Complex Sugars (Bioses and Trioses) by 

 the Ultra-violet Rays.* — MM. Daniel, Berthelot and H. Gaudechon 

 have systematically investigated the action of ultra-violet light upon 

 polyose sugars. They find that the effect is to decompose the complex 

 molecules into simpler ones. Thus, for example, maltose becomes 

 glucose + glucose ; and saccharose becomes glucose + levulose. In short, 

 while the decomposition by hydrolysis, necessary to render the sugars 

 assimilable by the animal organism, is naturally performed by the 

 action of ferments, the authors have obtained it by the ultra-violet rays. 

 This suggests that the efficacy of ferments is not of a material, but of a 

 dynamic, order ; and that the key of their action must be sought not 

 in their formula of constitution, but in their vibratory rhythm. 



(6) Miscellaneous. 



Hayem-Sahli Haematocytometer.t — This apparatus consists of the 

 following parts : — 1. A pipette, calibrated to hold 1-5 c.mm. for the 

 purpose of counting the red cells. 2. For counting leucocytes a similar 

 pipette calibrated to take from 5-25 c.mm. 8. A pair of diluting 

 pipettes for measuring quantities of the diluent ranging from 250-500 

 c.mm. 4. Two glass cells, marked red and white, for preparing the 

 mixture of blood and diluent. 5. A glass spatulum for stirring the 

 mixtures. 6. Two chambers, with plane-parallel cover-glasses respec- 

 tively 0*2 and O'l mm. deep. Unlike other patterns of the counting 

 chamber, these are not provided with a grating, as this is contained in 

 the eyepiece. On the floor of the chamber, however, there are concen- 

 tric markings for controlling the position of the Microscope. 7. An 

 eyepiece, provided with screw-in grating, consisting of a large square 

 divided into sixteen small squares. The small squares provide a means 

 of orientation ; the large square serves exclusively as the counting unit 

 of reference. 8. Tables which supply for a given dilution and depth of 

 chamber the number of corpuscles per cubic millimetre, corresponding 

 to the mean number counted in a square. 9. A mechanical stage, with 

 travel check ; the action of the limit catch is felt distinctly as the milled 

 heads are turned, each space corresponding to a microscopic field. 



* Comptes Rendus, civ. (1912) pp. 1506-9. t Leitz Circular. 



