Page:The Oak.djvu/182

From Wikisource
Jump to: navigation, search
This page has been validated.
164
THE OAK.

cells multiply and form the gall. This is a mere outline sketch of the matter, however, for the differences in behavior are enormous. Each insect causes the formation

The Oak (Marshall Ward) Fig 50.jpg

Fig. 50.—Portion of the spore-bearing hymenium of Merulius lacrymans, the fungus of "dry rot."

of a specific kind of gall, differing in shape, size, color, and other characters from those caused by other gall-insects. There are many kinds, and only a few can be mentioned here. Each species of oak may have its