248 



Proceedings of Indiana Academy of Science 



7. Inoculation Chambers. Any sort of an enclosure which will per- 

 mit the maintaining of a saturated humidity and a temperature opti- 

 mum for the rust under investigation, will do for an inoculation chamber. 

 When seedlings are to be inoculated sufficient light should be admitted 

 to prevent excessive etiolation during the inoculation period. Unless 

 provision for cooling the chamber is made, direct sunlight is to be 

 avoided on account of the resulting high temperatures. Belljars have 

 been quite generally used and are very satisfactory where the number 

 of plants being inoculated is small. In this laboratory these are placed 

 on a layer of wet sphagnum under the greenhouse bench where they 



Fig. 

 carrying 



2. Plant Covers which may be used cithor 

 of rust cultures. 



for inoculation chambers or for 



receive diffused light. They have the disadvantage, however, of being 

 easily broken and costly to replace. 



As a substitute for belljars a modification of a plant cover (fig. 2) 

 such as is used to shelter early jDlanted cucumbers or melons has been 

 found very satisfactory. These plant covers, as usually constructed, 

 are too low for plants in pots. As a consequence it is necessary to have 

 them made to order. Two sizes are constructed, one 21 inches high for 

 9-inch pots, and the other 14 inches high for 3- or 4-inch pots. The 

 accompanying illustration (fig. 2) shows the general character of these 

 plant covers. They are of cypress, except for two panes of glass which 

 serve for the roof, and in consequence are very durable. If the glass 

 is broken it usually can be replaced by cutting down broken greenhouse 

 panes. These plant covers are u.sed not only for inoculation chambers. 



