406 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



(4) Photomicrography, 



Photographic Dark-box for Field Work.*— The difficulties en- 

 countered in doing photographic work in the field where dark-room 

 conveniences are lacking led to the making of a dark-box which is an 

 adaptation of the inoculating chamber in common use in plant pathology. 

 Elda R. Walker has found it so satisfactory that he uses it entirely for 

 plate work even in the laboratory where a dark-room is available. The 

 dark-box (fig. 42) is a plain light-tight box 24 in. long, 18 in. wide, 

 and 20 in. high. It is made of light-weight lumber f in. thick. To 

 avoid all chances of light entering, it is made of well-seasoned lumber ; 

 all corners are joined, as shown in the accompanying diagram, at k, and 

 all seams in the sides are made by inserting a strip-" tongue," % x £ in. 



Fig. 42. 



in cross-section, as is shown at m in the diagram. Besides these pre- 

 cautions, all joints are glued as well as nailed. In the right-hand end 

 is a door, 14 x 11 in., for admitting to the box plates, plate-tank, and 

 such things as are to be used in the work. In the top and back are red- 

 glass windows, 10 x 8| in., set firmly with putty. The back one serves 

 to admit light, and the top one permits the operator to see what he is 

 doing in cases where light is needed. (When using the windows it is 

 well to cut out side lights by throwing a focusing cloth over the head. 

 For most work, however, the windows are covered by wooden doors, and 

 the work is done without sight.) All doors are of the sliding kind and 

 work in a groove, as is shown in the diagram at a. This shuts out all 

 light. In front of the box (fig. 42) are two round holes for the operator's 

 arms ; these are 6 in. diam. They are 7 in. apart, and 6 in. from the 

 bottom of the box (outside measurement). These are convenient dinien- 



* Trans. Amer. Micr. Soc, xxxiii. (1914) pp. 51-4 (5 figs.). 



