ZOOLOaY AND BOTANY MICROSCOPY, El'C. .»2/ 



rLeitz: Electrical Object-Stage.* — This stage (fig. 74) affords a 

 means of electrically stimulating histological preparations during observa- 

 tion under the ^licroscope. It can also be used for studying microscopic 

 changes occurring in electrolytic processes. The current is conveyed by 



Fig. 74. 



means of two terminals and two adjustable electrodes, which carry fine 

 platinum wires at their extremities. The whole is mounted on a 

 vulcanite plate which is secured to the stage of the Microscope by means 

 of two pins. 



New Geiger Microscope Lamp.f — M. Wolff speaks in the highest 

 terms of the capabilities of the new 2-ampere Ewon lamp, brought 

 out by the firm of J. Geiger, of Munich. He considers that it 

 possesses practically all the advantages of the 4-ampere Ewon lamp, 

 combined with greater suitability to subjective microscopy. It not 

 only compensates for the best daylight (which cannot be said for pet- 

 roleum, gas, incandescent, and Nernst light) but makes dayhglit super- 

 fluous, because it furnishes a pure white light capable of graduation. 

 The lamp with 200 normal candle brightness completely attains what 

 should be expected from an ideal Microscope lamp. When used with 

 the strongest dry or immersion systems or with the strongest compensa- 

 tion oculars it gives a brilliantly bright pure white field, whose intensity 

 for subjective work requires to be subdued by a matt-glass disk. It 

 follows that the brightness is sufficient under the most trying conditions 

 to produce satisfactorily bright images. In extraordinarily difficult 

 cases the mere extension of the condenser-tube raises the brightness to 

 the required degree. The amount of heat produced appears to be very 



* Leitz' Catalogue, 44d, p. 31. 



t Zeitschr. wiss. Mikrosk., xxix. (1913) pp. 328-35 (2 figs.). 



