r,i2 



SUMMARY OF CURRENT RESE\RCHES RELATING TO 



hollow and a large cover-glass is placed over it (Fig. 43). If the 

 cover-glass projects just over the top of the slip it is easy to lift it off. 

 When the slip, duly charged with the gathering, is on the stage of an 

 inclined Microscope the cover-glass will not slip off, because it will be 

 held by the ledge, neither will the small excess of water, squeezed out 

 between the cover and the slip, run down on to the stage, because the 

 ledge will catch it. 



The writer, who is indebted to W. Chaffey for this simple and 

 excellent device, has now used it for some time in preference to the 

 different forms of compressors that are made. One point is that these 

 slides should be of a proper thickness to suit the focus of the sub-stage 

 illuminator ; for if the focus of the illumiuator is long and the slide 

 thin there will be constant trouble, because the oil will run away, and a 

 slip-equalizer must be provided. If the slip is thick and the focus of 

 the illuminator be short the illumination will be very poor indeed. It 

 is better, therefore, in the first instance, to find the precise working 



Fig. 43. 



distance of the illuminator and provide a slip of a proper thickness to 

 suit it, then the maximum amount of illumination will be secured and 

 no further trouble experienced. Note, with the above objectives aud 

 deep eye-pieces of 1 or a |-in. focus the focused image of the edge of 

 the flame of a paraffiu Microscope lamp (used direct if the Microscope 

 stands high on its trunnions, but with the plane mirror if low) will 

 yield a very satisfactory and critical illumination. 



Method of Making Toto Mounts of Unicellular Forms.*— 

 R. A. Nesbit describes the following procedure : The material is killed 

 and fixed in whatever solution the investigator has found most 

 satisfactory for the particular Algaj or Protozoa with wliich he is 

 working. It is washed in bulk in the usual manner and carried 

 through upgraded alcohols as far as 60 p.c. It is allowed to settle 

 completely in this grade. A thin layer of albumen fixative is smeared 

 on thoroughly clean slides. A drop of the material is then drawn up 

 with a pipette and placed on the slide. The alcohol coagulates the 

 albumen and causes the cells to adhere to the slide. They may then be 

 dipped into 60 p.c. alcohol and afterwards to upgraded alcohols. It is 

 possible to use such stains as Flemming's and iron-hasmatoxylin rapidly 

 and with precision. Before using Flemming the cells must be hardened 

 in 95 p.c. alcohol. 



* Trans. Amer. Micr. Soc, xxxv. (1916) p. 140. 



