104 



BACTERIA IN RELATION TO PLANT DISEASES. 



When ready to make the transfers or to pour the plates, close the windows, 

 wipe up the tables, and wet down the floor, window-sashes, etc., with distilled water 

 or boiled water, and reduce the air-currents within the laboratory to a minimum 

 (especially when transfers are to be made in the open room) by keeping the doors 

 shut and restricting the movements of all persons who may be in the room. It is 

 much better to do all of this work in specially constructed small rooms (plate n) 

 than under hoods (plate 12). Hoods are open only in front. They may be made of 

 any convenient size. The one here figured is is 32 by 39 by 20^ inches, outside 

 measurements. When one is far from laboratories small hoods may be extempor- 

 ized out of clean paper, or cultures may be poured and transfers made inside of a 

 clean pail or jar, turned down on its side. Any method, in fact, which restricts 



the movement of air past open plates and 

 tubes will be found serviceable. 



The work-shelf of the room shown 

 in plate 1 1 faces a window as wide as the 

 room, and extending from the level of the 

 shelf to the height of the other windows 

 in the room. This window faces south 

 and is only 6 feet from a well-lighted win- 

 dow in the outer wall of the building. The 

 room also receives bright light from the 

 west side. At the front end of the shelf 

 are a Bunsen burner with cut-off flame, a 

 box of safety matches, a box of rubber 

 bands, and two tumblers one for burned 

 matches and one for platinum loops, 

 needles, forceps, etc. Immediately under 

 this part is a narrow drawer for pencils, 

 note paper, knives, etc. At the back end 

 are a few wrapped Petri dishes, a nivella- 

 tion apparatus, a flask of sterile water, and 

 a crate of media. Underneath this part is 



Fig. 89.* 



a second shelf 3 inches below the first, where Petri dishes and tubes containing solid 

 media may be put out of the light as fast as inoculated. The size of this room 

 (inside measurement) is 4 by 4 by 10 feet, and it is large enough. No provision is 

 made for ventilation, because air-currents in a culture-room are very objectionable. 

 The windows, walls, and floor are wiped up with distilled water before making 

 transfers. Outside is a bit of the author's private laboratory. At the right is the 

 microtome and behind it on the wall are deep and shallow drawers ; 69 is for bulk 

 paraffin; 70 A, B, C, D, E, are cut into small compartments used for paraffin blocks. 

 The very shallow drawers are for ribbons which can not be mounted the day they 

 are cut ; 72 has a series of shelves opening on the south side and is used to hold 

 photographic printing frames. 



*FiG. 89. Pine block with inch holes, convenient for holding test-tube cultures during exam- 

 ination, or tubes of media which are to be inoculated. A good size is 95/2 by 3 l / 2 by i^ inches. 



