Most of the readers of the Gardeners' Monthly know that the curl in the peach leaf is caused by a fungus, what that fungus is, how it operates and how very injurious to the peach tree is its operation. But it does good to repeat lessons which have been taught, and especially when the lessons come from varied teaching; so we give here the latest lesson given by Professor Penhallow through the columns of the Country Gentleman :

"The curl in the peach leaf is caused by the growth of a fungus known as Exoascus deformans, Freckel (Ascomyces deformans, Berk, Taphrina deformans, Tul.). During its growth it not only causes the leaves to curl, but to lose their green color and become more or less red and yellow, and we see from this, therefore, that such leaves are incapable of performing their normal functions in the assimilative processes of the plant. The necessary result of this is, that there is a very limited formation of wood while such leaves remain on the tree. For this period, therefore, it must be admitted that the curl does exert a positively injurious influence. It is found, however, that these leaves fall off during the month of June, and a new set of leaves free from curl appears. Upon these, then, the entire growth of the season depends, and because, unless otherwise diseased, the tree then very frequently makes a fine growth, fruit-growers generally believe that the curl is of no importance, and that it does not injure the tree at all."