228 



ot copal varnish, by combining one ounce of copal with ten of benzine, 

 a portion of which I poured on a glass slide one inch by three, instantly 

 Fig. 2. allowing all the superfluous 



varnish to drain off. In 

 about thirty minutes after 

 this operation the mildewed 

 leaf was pressed gently on. 

 the varnished glass, when 

 the mycelium was trans- 

 ferred to it, owing to the 

 slightly sticky character of 

 the varnish. When mount- 

 ed in the usual manner they 

 may be photographed. The 

 threads of the mycelium are 

 not more than about the 

 twenty-thousandth of aa 

 inch in diameter ; from these 

 short threads protrude, on 

 the terminals of which grow 

 bundles of naked spores, 

 arranged as shown. 



In my investigations of 

 pear-tree blight, I have 

 failed to discover any fungi inhabiting those portions of blighted bark 

 which seem deficient of albuminous matter. The myceliums when once 

 formed, will doubtless spread over substances foreign to them as food ; 

 but the protoplasmic portions seem only to foster there the germination 

 of fungi. 



There may be periodic times when fruit-trees and cereals will attain 

 great perfection in growth, and appear wholly free from external fungoid 

 disease, notwithstanding the soil, either mechanically or chemically con- 

 sidered, is not of the most favorable character. Such appearances may 

 lead to an extension of fruit-tree planting on such soil ; but with a 

 single unfavorable season the fruit-grower's hopes may perish with his 

 trees and labors.* Fungi seem ever present, waiting in undeveloped 

 forms their time for action. 



Some interesting experiments are being prosecuted by Mr. William 

 Saunders, superintendent of the Department grounds, in relation to 

 pear-tree blight, particularly during the last two years. A pear-tree 

 which was badly blighted on its main trunk was made the subject of 

 special experiment. Nearly all of the bark was blighted within three 

 feet of the ground, only about an inch and a half in width being left to 

 connect the upper part of the tree with the unblighted bark at the base. 

 The affected part was removed and the sap-wood left quite exposed to 

 view; but to prevent injury from the air it was at once coated with a 

 composition of carbolic acid, sulphur, and lime, and largely diluted 

 with water. After the lapse of two years the tree has wholly recovered 

 and the denuded part is again covered with new and healthy bark. The 

 tree in all respects presents a healthy appearance. Many other trees 

 much affected with blight were coated heavily with the sulphur com- 

 positions and have evinced marked signs of improvement. It is intended 

 to continue these experiments on a larger scale, until safftciently numer- 

 ous and well-established facts attest the best mode of treatment. The 

 Department grounds consist of a heavy, compact, partially undrained 



