20 THE AMERICAN BOTANIST 



is a mistake. Many flowers in which the ovules were fertilized 

 appear to be thrown down before the fruits have had a chance 

 to develop. At the same time the fact must be overlooked tliat 

 there are many flowers in which pollination does not take place 

 that nevertheless give rise to perfect fruits though seedless. 

 Among familiar examples may be named the small grape from 

 which the dried currants of the shops are obtained, the banana, 

 the naval orange, the sultana grape, and various apples and 

 pears. Such fruits are called parthenocarpic fruits and serve 

 well to illustrate the fact that there no hard and fast lines in 

 nature. There are certain lines along which each plant part 

 develops, but when occasion presents itself the lines may be 

 abandoned. 



Use of the Caruncle. — A considerable number of spe- 

 cies scattered throughout the plant world have seeds in which 

 the seed coat or testa grows out at the point where the seed is 

 attached to the ovary forming a fleshy object called the car- 

 uncle. Those w ho hold the opinion that no plant structure has 

 been evolved unless called into existence by some need for it. 

 have been puzzled to account for the caruncle. For a long 

 time it has been suggested that ants and other small insects 

 might find the caruncle palatable and thus carry the seed away 

 for the sake of it, and effecting a wider distribution of the 

 plant. The loss of the caruncle appears in no way to hinder 

 the germination of the seed. Additional evidence in support 

 of the theory that this object is useful in seed dissemination 

 has recently been found in the case of the European gorse 

 ( Ulex europacus) which is found abundantly along roadsides, 

 and about cottages where ants are also found. In such places 

 it even invades plant groups w^here it does not grow naturally. 

 This is found to be due to the fact that that the seeds are spread 

 bv ants which carry them away for the sake of the 

 brio-ht orange oilv caruncle. The Ijroom ( Cytissus scoparius 

 is also said to be distributed in this way. Plants whose seeds 

 are thus distributed are called mvrmecochorous plants. 



