284 NOTES AND MEMORANDA. 



means ordinarily employed to clean the teeth had no effect 

 on the parasites, whilst soapy water appeared to destroy 

 them. — Lancet, December loth, 1873. 



Holman's " Siphon Slide" for the microscope is composed 

 essentially of a strip of plate-glass, three inches by one inch 

 wide, but double the usual thickness, in the upper surface 

 of which has been ground a shallow groove, elliptical in both 

 its transverse and longitudinal section, and deeper towards 

 one extremity. The excavation is so arranged as to receive a 

 small fish, tadpole or triton, and retain it without, on the 

 one hand, injury from undue pressure, but without, on the 

 other, permitting any troublesome movements beneath the 

 thin glass cover, which, when applied, forms the ceiling of 

 the cell. The great improvement of this slide consists, how- 

 ever, in the imbedding of a small metallic tube (communi- 

 cating with each extremity of the groove), in either end ot 

 the slide, and the adaptation to these two tubes of pieces ot 

 slender caoutchouc pipe, about eighteen inches in length, 

 one of these being intended for the entrance, and the other 

 for the exit of any fluid, cold or hot, which it might be desir- 

 able to employ. 



For examination of larger reptiles, and for demonstrations 

 wath the gas-microscope, a slide four inches long, with two 

 oval concavities, and a narrow groove more deeply cut for the 

 body of the creature, has been devised. With such an appa- 

 ratus, through which a current of ice-water can be passed, 

 the injurious heating effect which ordinarily attends the use 

 of calcium or electric light to illuminate living specimens is 

 entirely counteracted. 



When in use it is only necessary to place the animal with 

 some water in the groove of the slide, cover with a sheet of 

 thin glass, immerse the end of one of the caoutchouc tubes 

 in ajar of water, and then, applying the mouth to the ex- 

 tremity of the other rubber pipe, make sufficient suction to 

 set up a flow of the liquid through the apparatus. The 

 stream of fluid (of course bathing the animal in the cell 

 during its passage) can readily be kept up as in any other 

 siphon for hours or days, and its rapidity exactly regulated 

 by graduated pressure upon the entrance -pipe, so that in 

 this way a triton may be examined continuously (as stated 

 by Dr. J. Gibbons Hunt) for a whole week without material 

 injury. 



Among the great advantages of this very ingenious con- 

 trivance may be enumerated — first, its security, — the animal 

 being prevented from escaping, and the joints of the appa- 



