The Plant 
47 
has taken place, great changes go on in the rudimentary 
fruit. In some cases the walls remain thin and leathery, 
as in the seed vessels of the Iris. In others a great develop- 
ment of the walls of the ovary takes place, as in the Cherry, 
Plum, &c., when we get what is commonly known as the 
Pineapple 
fruit. If we examine a plum, we find it is made up of 
three distinct parts: the epicarp, or skin; the mesocarp, 
or fleshy part; and the endocarp, or stone. Such fruits 
i are known as drupes. 
Other kinds of fruits, such as the Gooseberry, Currant, 
I &c., have the mesocarp filling the inside, with the tiny 
