ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 



669 



in a Microscope, because there is no stereoscopic projection, and the 

 shape of bodies can only be known by differences of focal adjustment. 



The instrument, like all of Messrs. Leitz' work, is most beautifully 

 made, and it is a thousand pities that Germans throw away such 

 excellent work on such impossible models. 



The cam was first applied to the fine adjustment of a Microscope by 

 Wenham in 1886, but it was used for stage movements by Swift in 

 1884." * 



New Regulating Arrangement for a Hot Stage.| — The advan- 

 tage of this apparatus, designed by R. Kraus, is " that a constantly 

 warmed water-supply can be applied to an object-stage and keep it at a 

 constant temperature the whole day long." The apparatus consists of a 

 glass hollow stage communicating by means of indiarubber tubes with the 

 two chambers of a heated reservoir. The whole arrangement involves 

 the principle of circulation, and the effect is to produce a steady flow of 

 water at a constant temperature through the stage. The water on 

 leaving the stage goes to the lower chamber, which is a sort of furnace, 

 whence it rises to the reservoir proper ; thence it gravitates to the stage, 

 and so on. The heating of the furnace is effected by a suitable gas 

 flame, and a thermostat in the reservoir controls the temperature of the 

 flow. The temperature of the stage is about 8°C. less than that of the 

 reservoir and the object-holder would be about 4° C. still lower. 



Watson's New Scop Mechanical Stage. — The principal advan- 

 tages offered by this new stage exhibited at the June Meeting (fig. 155) 



Fig. 155. 



are great range of movement, as much as 3 in. being given in the 

 horizontal direction, and a clear surface for working purposes. The 



* This Journal, 1886, p. 1052 (figs. 220 and 221). 



t Centralbl. f. Bacterid., xxxii. (1902) p. 467 ; and Zeit. f. Wise. Mikr., xix. 

 1903) p. 347 (1 fig.). 



Oct. 21st, 1903 2 x 



