120 BACTERIAL DISEASES OF PLANTS 



for insect depredations and treated for the same like other 

 herbarium material. 



Alcoholic Material. Quantities of this should be preserved 

 for two purposes: a, class use; 6, permanent records and ex- 

 hibition purposes. The former must be fixed in Carnoy's 

 fluid or some other suitable fixative before transfer to the 

 alcohol. Flat (parallel-walled) jars may be used for the ex- 

 hibition collection, which may be set off by a background of 

 milk-white glass placed inside the jars, though this is not abso- 

 lutely necessary. Any alcoholic collection must be examined 

 once a year and leaking jars refilled and resealed. 



Pathological material may be preserved, with the green color 

 of leaves and stems retained, by boiling the specimens for about 

 5 minutes, more or less (1 to 10 minutes) in 80 parts of distilled 

 water to which has been added 20 parts of glacial acetic acid 

 saturated with copper acetate. The treated specimens should 

 be rinsed in water and placed permanently in water containing 

 5 per cent formalin, or in localities not subject to freezing they 

 may be kept in sulphurous acid water (Gino Pollaci's method). 



Microscopic Preparations. These may be laid in flat trays 

 or in grooved wooden boxes. The writer uses the common 

 Pillsbury boxes which hold each 25 slides. These slides have a 

 gummed label on one or both ends bearing the block number and 

 other necessary data, i.e., object, date, kind of stain, etc. These 

 should be kept in the dark. The slide boxes in my laboratory 

 are filed either under the name of the parasite or serially. 



PREPARATION OF ILLUSTRATIONS 



Photographs. The general excellence of photographic ap- 

 paratus in recent years, and the slight cost of plates and films, 

 render this method of making records extremely serviceable. 

 The student who is planning a career in science should determine 

 from the start to be master of all the common methods of photog- 

 raphy. In every locality, nearly, there is some one who can 

 teach him the rudiments, and even if not, good journals and 

 books on the subject are now numerous and inexpensive. There 

 is, therefore, no excuse for neglect of this interesting and im- 



