258 The Scottish Naturalist. 



in most species when the conditions around them are changed — 

 e.g., in poor or stony soil as contrasted with rich fertile ground, 

 in open or in shady places, and so forth; hence the amount of 

 importance attached to diversities in these parts is very limited. 

 On the other hand, the organs of reproduction {i.e., flowers, 

 fruits, and seeds), are less directly exposed to the influence of 

 surrounding conditions ; and, save in number, and to some 

 extent in size, they are hardly modified by the influences that 

 so markedly act on the organs of vegetation. Accordingly, they 

 are found to be far more constant in form and in structure, and 

 hence are chiefly used by sys-tematists. But the flowers and 

 fruits, though but little affected by the causes above-mentioned, 

 are yet exposed to influences from which the other parts are 

 exempt. These seem to have in course of time had a great 

 effect in modifying the structure of both flowers and fruits in 

 many plants to suit the conditions under which they live. These 

 influences as regards flowers have been studied by careful and 

 enthusiastic observers in Great Britain, but more especially in 

 Germany ; and numerous works, some of great merit, have been 

 written on them and on their effects. 



In the flowers the great requisite is the conveyance of the 

 pollen from the anthers to the stigma, so as to fertilise the 

 ovules. In many plants this is effected by the wind, but in 

 others insects are the bearers of pollen ; and it is in these that 

 we meet with the most striking and beautiful forms of flowers. 

 There is reason to believe that very great modifications of form 

 and structure have been brought about in these in course of 

 time, suiting them for visits of insects, the structure of which 

 specially enables them to convey the pollen aright, while colour 

 and size have also been greatly affected in the same way. 

 Hence characters liable to such influences must be used with 

 much caution. 



In the fruits modifications are beneficial for a new object — 

 viz., the wide distribution of the seeds, and the agents are for 

 the most part different ; hence the modifications resulting from 

 their action are of a different nature. Frequently the result may 

 be attained in closely allied plants by modification of distinct 

 parts, while the same means may be employed in two or more 

 plants not at all closely related. Therefore, care is required to 

 distinguish between such adaptational resemblances and those 

 due to relationship, as they are of very different value to the 

 systematist and to the genealogical botanist. Examples of close 



