506 EXPERIMENTAL PHARMACOLOGY 



of each end of the kit. This will reduce the size of the kit 

 opening to approximately 314x4 inches. The regular lan- 

 tern slide plate is placed in this opening and the kymograph 

 record is photographed directly onto the lantern slide. De- 

 veloping is carried out exact!}' as with a negative but the 

 image usually shows up very quickly and over-development 

 should be carefully avoided as this gives dark areas over 

 part or all of the slide. The slide is developed, fixed, washed 

 and dried and is then ready for the mat, cover and binding 

 .strips. 



It is of particular importance to note that lantern slides 

 of black kymograph tracings should be made before the 

 tracing is varnished. In this condition an absolutely dull, 

 jet black background is presented in which the record shows 

 as perfectly clear white lines. This kind of an object is 

 most favorable for photographing. The paper on which the 

 records are made should always be smoked good and black. 

 From small kymographs the records may conveniently be 

 removed and pinned to a copying stand as shown in Fig. 

 386. The most convenient form of light for this purpose 

 is an electric arc light which can be raised or lowered to 

 ;suit the height of the table, etc. The light should hang just 

 over the front part of the camera. Two arc lights (one on 

 each side) or mercury vapor lamps possess certain ad- 

 vantages over the arrangement illustrated but are consid- 

 erably more expensive. 



Records on large kymographs may readily be photo- 

 graphed on to lantern slide plates while the paper remains 

 on the drum. The camera is placed on a tripod and focused 

 on the record which may be lighted either by an adjustable 

 arc light or by daylight. The image on the lantern slide 

 should be made well within the limits of the plate, a margin 

 of 14 to 1/2 i- ncn being left around the border of the plate for 

 the mat. Xote that lantern slides are always used in the 

 lantern with the long dimensions of the slide placed hori- 



