VII] COHESION AND ADHESION 61 



of this gradual sinking or pulling in, as it were, of the 

 gynoecium, as the flower becomes more condensed from 

 above downwards ; while the various stages of perigyny 

 must be looked upon as intermediate conditions between 

 the two. But the early arrest of onward growth in the 

 central part of the true apex of the flower, which leads to 

 this condensation, brings other changes in its train, some 

 of which we will now examine. 



One of the principal of these is that the crowded 

 incipient organs sepals, petals, stamens and carpels 

 have no longer room to grow out as separate appendages 

 or outgrowths, each with its own distinct insertion ; and 

 so, although each begins to develope as a minute organ on 

 its own account, it continues its growth so closely united 

 with some neighbouring organ, of like or different kind, 

 that the tissues of the two are perfectly continuous at 

 the base, and form a sort of whole, where they pass into 

 the axis of the flower. These unions of the parts of the 

 flower are extremely common, and are often somewhat 

 loosely spoken of as if the parts referred to had been 

 joined or stuck together: this, of course, is not the case, 

 since they have never been developed as independent 

 and separate organs, but have merely grown up in unison. 



It is agreed that when this coalescence or union of 

 organs concerns those of like kind it shall be termed 

 Cohesion, but where it concerns organs of different value 

 it is called Adhesion : thus, stamens cohere with stamens, 

 but adhere with petals, sepals, &c. 



Cohesion is very common, as is to be expected from 

 the crowded positions of organs arranged in whorls on 

 a shortened axis, and it occurs in all regions of the 

 flower, reminding us of the similarly frequent cohesions 

 of opposite or whorled leaves in other parts of the shoot. 



In the flowers of the Bladder Campion, Corn-cockle, 



