MAY AND JUNE 



247 



Doubtless most people have heard of Darwin's illustra- 

 tion of the remote causes determining animal or plant 

 existence, as illustrated by the relationship of cats to 

 clover. He says that the bumble bees, which are neces- 

 sary to the fertilization of the flower, have, for an invet- 

 erate foe, field mice. These, in turn, are preyed upon by 

 the cats. Therefore in any given community the pres- 

 ence or absence of cats determines the presence or ab- 

 sence of clover. Or, as some one facetiously puts it, for 

 the well-being of clover there must be plenty of old 

 maids. 



White clover is also commonly found. It does not 

 differ materially from 

 the red, except that l^ 

 the tube of the corolla 

 is short, and there- 

 fore it is frequented 

 by a larger variety of 

 insects. 



Jack -IX -THE- PULPIT 

 (Arisaema triphyl- 

 lum) : 



In spite of the 

 fact that the leaves 



^-PISTILLATE FLOWERS 



PISTILLATE FLOWERS 



-STAMINATE FLOWERS 



Jack-in-the-pulpit. 



of this plant are 

 netted veined, it be- 

 longs to the one-seed- 

 leaved plants (mono- 

 cotyledons). It is a near relative of the skunk cab- 

 bage, the earliest flower to bloom in the spring, and 

 of the stately calla. Like them, its real flowers are situ- 

 ated inside the sho-wj- envelope, and, in this case, at the 



