ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 713 



Proceedings, referred back to the committee witli instructions to con- 

 tinue its investigations, and the matter considered at the next annual 

 meeting. 



Grunow's Camera Lucida.* — Mr. J. Grunow has modified his 

 camera lucida by a slight change in the opening through which the 

 image of the object on the stage is seen. By reducing the opening to 

 a diameter of • 05 inch, he states that the pencil point is still more 

 clearly seen, while sufficient light comes from the object to show the 

 details. 



Standard Body-tube for Microscopes.f — Mr. G. E. Davis sees 

 " no other way of bringing about a standard gauge than by publishing 

 the diameters of all stands now in the market, and advising piu'chasers 

 to choose the larger bore. A small eye-piece will fit a large tube, and 

 can be centralized and kept tight by a paper adapter or collar made 

 by the microscopist himself; but a small tube will only take a small 

 ocular, and no other, so that the diameter of the body-tube of the 

 Microscope should always be taken into consideration on the purchase 

 of an instrument." 



A table of thirteen English and three foreign stands is given with 

 the diameters of the oculars, both the body and the neck over which 

 the camera lucida usually fits. 



Sliding Body-tubes.t — Dr. J. Edwards Smith thinks that there are 

 some advantages in a sliding body, that are not to be obtained by the 

 use of the rack and pinion. 



For example : supposing we are working over wet preparations, 

 and unfortunately the front of the objective becomes immersed in the 

 liquid, a misfortune liable to occur daily. It is then, in such cases, a 

 positive convenience to be able to pull the body-tube out of the jacket, 

 clean the objective, and return to its place. All this can be done in 

 much less time than would be required, were the instrument furnished 

 with rack and pinion, to unscrew the lens, clean, and screw in place 

 again. 



McCalla's N'ose-piece.§ — Prof. A. McCalla refers to a form of 

 nose-piece which he considers to have some advantages over Pease's 

 " Facility " nose-piece and that of Nelson. " It is simply a form of 

 bayonet catch which would dispense entirely with the screw, and hold 

 the objective perfectly secure against sagging on one side or working 

 loose when the adjustment collar was in use." 



Smith's Rotating Stage. II — Dr. J. E. Smith describes "the stage 

 which he has had in daily use for years, and one that has to a con- 

 siderable extent been copied by his friends." 



Provide a sheet of well-hammered brass, heavy enough, so that 

 when planed or turned down the stage shall be 1-1 6th of an inch in 



* Amer. Mon. Micr. Joiu-n., iv. (1883) p. 13S. 



t Micr. News, iii. (1883) pp. 219-20. 



X ' How to See with the Microscope,' 1880, pp. 44-5. 



§ ' Chicago Times,' 8th August, 1883. 



il 'How to See with the Microscope,' 1880, pp. 27-8, 



