ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



207 



Krtiss Apparatus for Optical Demonstrations.* — The firm of 

 A. Krtiss, Hamburg, have devised a set. of apparatus by which all the 

 usual optical phenomena can be easily and clearly demonstrated to a 

 class of students. A LilHput arc-lamp is used as a light-source, and is bo 

 adjusted on an iron pillar as to emit horizontal rays through iron plates 

 pierced in various ways. The effect in a dark room is like miniature 

 search -lights, which by passing through lenses — by reflection at surfaces, 

 and so forth — facilitate a lecturer's explanations. 



Apparatus for Micro-operations.f— S. Tschachotin, who has lately 

 described a photo-chemical cell-operation method suitable for micro- 



FiG. 19. 



scopically dealing with the smallest cells,J now describes a mechanical 

 method applicable to fairly large cells, e.g. those of Amphibians. His 

 method facilitates such operations under the Microscope as sectionizing, 

 juxtaposing, extirpation, resection, localizing electrical or thermal agencies 

 — especially with small objects. 



Fig. 19 shows the apparatus. It consists of a metal ring R fitted to 

 the lower part of the Microscope tube and fixed by a screw S. The ring 

 has a horizontal slit 81 in which works a small pin Sb, which by application 

 of a screw can be clamped in any position on the circumference of the 

 ring. A toothed bar Z is attached to the pin Sb and operated by a rack 



* Deutsch. Mech.-Zeit., 1913, pp. 1-6 and 13-15 (22 figs.). 

 t Zeitschr. wiss. Mikrosk., xxix. (1912) pp. 188-90 (1 fig.). 



t Die Mikroskopische Schahlenstichinethode,eine Zelloperationsmethode (Biol. 

 Zentralbl., 1912). 



