160 



THE AMERICAN MONTHLY 



[June, 



Generally the first noticeable effect of the disease is a brown or 

 black discoloration of the leaves (Fig. i), those nearest the ground 

 being affected first. There soon appears, however, on the under 

 surface of the leaves, a whitish down, which spreads rapidly to the 

 stem, and soon affects the whole plant. Under the microscope the 

 leaf fungus appears as shown in Fig. 2 The minute spores de- 

 velop in great numbers and fall to the ground, whence they are 



Fig. 2. Manner of growth of the phytophthora. 



washed into the soil by rains and thus aflbct the forming tubers. 

 The spores are also carried long distances by the wind, and from 

 one field others for miles around may be affected. The develop- 

 ment and growth of JMao'osporiuin is similar to tiiat above given. 

 The remedy is to be found in spraying with the Bordeaux 

 m i xtu re. — A nierica n Agriculturist. 



Exhibits at the Chicago Exposition. — 1. 



\V. Watson & Sons, 313 High Holborn, London, and 78 

 Swanston street, Melbourne, Australia, are exhibiting in the 

 British Section specimens of the scientific instruments for which 

 they have a world-wide fame, and have sent out from London 

 one of their regular staff' who is conversant with the practical 

 manipulation and will consequently be able to explain the in- 

 struments in a far lietter manner than a catalogue will do. The 

 principal features of their exhibit are photographic cameras, 

 lenses, and accessories, microscopes and accessories, stereopti- 

 cons, surveying instruments, etc. 



