ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 1029 



the stage of the Microscope so as to project a little at both ends. On 

 it is placed a piece of ordinary blotting-paper which just leaves the 

 margins of the slide free ; a hole is cut out in the centre of this paper B 0, 

 and at one end is a triangular prolongation B', which is bent downwards 

 close to the slide. Water is drawn from a tumbler E by means of a 

 capillary tube D, and drops on to the blotting-paper. The author usually 

 makes the tube just wide enough to allow a small drop of water to escape 

 about every 20 seconds. The water is drained off by the triangular 

 prolongation of the blotting-paper already mentioned. An inverted 

 flask F, filled with water, has its mouth just touching the surface of the 

 water in the tumbler E, and keeps the level of the water in the tumbler 

 constant, thus ensuring the regular escape of drops from the capillary 

 tube D. The capillary tube has a thickened portion in the middle, 

 which is convenient to keep the tube steady. To be quite sure that the 

 tube will work properly, it is well to empty and refill it every 21 or 48 

 hours. On the right of the fig. the apparatus is represented in use. 



DixoK, H. G-.— Sub-stage Condensers. Engl. Mech., XL VIII. (1888) p. 199. 



Geosse, W. — Ueber Polarisationsprismen. (On polarizing prisms.) 



72 pp., 2 pis., Kiel, 1888. 

 KrCss, a. — Prismenkombination ans Ealkspatb zwecks Miscbung nnd Ver- 

 gleichung von Licbtbiindeln. (Prism-combinations of calc-spar for mixing and 

 comparing light-pencils.) 



[German Patent, No. 43,569, 27th September, 1887. Could be used as a 

 comparator such as Inostranseffs.] 



Zeitschr. f. Instrumentenk., VIII. (1888) p. 371 (1 fig.). 

 [Manton, W. p., and others.] — Sub-stage Condensers. 

 [Principally a description of the Abbe Condenser.] 



The Microscope, VIII. (1888) pp. 312-3. 

 Weiss, D. — Ueber die Hamatoskopie des Dr. A. HenoccLue. 



Prag. Med. Wochenschr., XIII. (1888) p. 117. 



C4) Photomicrography. 



Jeserich's Photomierographic Apparatus.* — Dr. P. Jeserich de- 

 scribes the apparatus shown in fig. 175, which can be used either with 

 sunlight or artificial illumination and either vertical or horizontal, and 

 an ordinary Microscope can be used, provided it has a horse-shoe base 

 with sufficiently wide space to admit the light from the illuminating 

 apparatus. 



The instrument consists of a rectangular iron base, to which are 

 screwed four vertical iron uprights of L shaped section, forming guides 

 for the camera to slide in. The camera can be fixed at any height to a 

 plate between two of the uprights by means of a nut and bolt passing 

 through a slot in the platfe. These two uprights are accurately graduated, 

 so that an index on the camera gives the distance of the objective from 

 the focusing plate. The index lies at a point a little below the focusing 

 plate ; consequently the zero point of the scale is placed at the same 

 distance below the objective, and the true distance between the plate and 

 the objective is then given by a direct reading. At the height of the 

 body-tube is a very shallow box, or kind of camera, fixed in the 

 same way by bolt and nut in the vertical slot, and united by a bellows 

 connection to the first camera. The lower face of the smaller camera has 

 in its centre a small opening provided with a screw-thread to receive a 



* Jeserich, P., ' Die Mikrophotographie,' 8to, Berlin, 1888, pp. 99-105 (2 figs.). 



