1682 



Journal of Applied Microscopy 



left entire, and also having a piece of the metal projecting on one side of the 

 ellipse, to be used as a handle. The elliptic piece is the shutter for admitting 

 or cutting off the light, and is manipulated by the projecting handle. 



With the upright stand tem- 

 porary mounts in water or other 

 fluid media can be photo- 

 graphed. This is particularly 

 valuable where research work is 

 being done ; as, for instance, 

 organisms growing in moist 

 chambers can be photographed 

 in their various stages of de- 

 velopment without any disturb- 

 ance of the mount. 



A good picture of the ordi- 

 nary, stained permanent mount 

 is easily enough obtained, but 

 where the live tissue is used, and 

 the fine detail is sought, greater 



care and skill are required. This 

 Fig. 2 — Transverse section of wood of Pinus taeda, taken . • i i r u i 



with two-thirds apochromatic objective and No. 4 IS particularly true of the lOW 

 compensating ocular, x8o. organisms, where the fixing and 



staining cause a certain amount of contraction, and consequently a loss of the 

 detail, and where one should necessarily use the live material to get a true 

 picture. For work on mounts which show little contrast of parts the substage 

 condenser provided with an upper and a lower diaphragm is invaluable. By 

 means of these all the finer details of structure can be brought out, even in the 

 colorless organisms. 



A procedure which helps 

 very much in the success of 

 the picture is to expose for 

 about four-fifths of the time 

 required with both diaphragms 

 almost closed, so as to get the 

 least possible light, but the 

 greatest contrast of the parts, 

 then for the final one-fifth of 

 the time, opening the dia- 

 phragms so as to admit a flood 

 of light. In this way both 

 detail and contrast are ob- 

 tained. 



For delicate focussing an 

 engraver's glass is the handiest, 

 as it can be set over the clear Fig. 3— Aspergillus oryzas, moist chamber culture, taken 



, , , with one-sixth inch objective and No. i eyepiece, 



spot — made by a cover-glass X550. 



