CONCERNING CLOVER. 73 



is in giving a preference to " listed " securities. Many persons seem 

 to think stocks and bonds must have a value if they are quoted at 

 some stock exchange. On the contrary, such a position is likely to 

 expose them to manipulation for purely speculative purposes. Stock- 

 exchange quotations, as a rule, are unsafe guides to buyers. Every 

 security must stand on its own merits, and purchasers have merely to 

 follow business principles as taught by the canons of common sense. 



COITCERNING CLOYER. 



Bt grant ALLEN. 



EVERY group of organisms, every genus and every species of 

 plant or animal, has certain strong points which enable it to hold 

 its own in the struggle for existence against its competitors of every 

 kind. Most groups have also their weak points, which lay them open 

 to attack or extinction at the hands of their various enemies. And 

 these weak points are exactly the ones which give rise most of all to 

 further modifications. A species may be regarded in its normal state 

 as an equilibrium between structure and environing conditions. But the 

 equilibrium is never quite complete ; and the points of incompleteness 

 are just those where natural selection has a fair chance of establishing 

 still higher equilibrations. These are somewhat abstract statements 

 in their naked form : let us see how far definiteness and concreteness 

 can be given to them by applying them in detail to the case of a famil- 

 iar group of agricultural plants — the clovers. 



To most people clover is the name of a single thing, or, at most, of 

 two things, purple clover and Dutch clover ; but to the botanist it is 

 the name of a vast group of little flowering plants, all closely resem- 

 bling one another in their main essentials, yet all differing infinitely 

 from one another in two or three strongly marked peculiarities of 

 minor importance, which nevertheless give them great distinctness of 

 habit and appearance. In England alone we have no less than twenty- 

 one recognized species of clover, of which at least seventeen are really 

 distinguished among themselves by true and unmistakable differences, 

 though the other four appear to me to be mere botanist's species, of 

 no genuine structural value. If we were to take in the whole world, 

 instead of England alone, the number of clovers must be increased to 

 several hundreds. The question for our present consideration, then, is 

 twofold : first, what gives the clovers, as a class, their great success in 

 the struggle for existence, as evidenced by their numerous species and 

 individuals ; and, secondly, what has caused them to break up into so 

 large a number of closely allied but divergent groups, each possessing 



