EVIDENCE FURNISHED BY SCIENCE OF LIKENESSES. 139 



B 



FIG. 67. SLOE AND ROSE, WITH THORNS AND PRICKLES. 



plants which in a wild state possess thorns alone produce full-grown 

 branches under cultivation. "Spinosae arbores cultura ssepius de- 

 ponunt spinas in hortis," said Linnaeus, and the Sloe itself illustrates 

 the remark. But the prickles of the Rose (Fig. 67, B), which might 

 readily be deemed thorns in miniature, now demand attention. The 

 prickle has no intimate 

 connection with the 

 stem. On the contrary, 

 it is merely a hardened 

 appendage of the skin 

 of the stem or leaf as 

 the case may be. A 

 prickle causes no 

 trouble in its detach- 

 ment from the stem, 

 and the botanist would 

 inform us that these 

 appendages in their true nature correspond to hardened hairs. 

 Lastly, we may meet with double prickles, or spines, which spring 

 from the axils of leaves and from the base of the leaf-stalk. In the 

 Acacias and the American Prickly Ash (Echinopanax) we may see 

 spines the origin of which is not hard to trace, and which spring from 

 the bases of the leaves. Just as the tendrils of the Smilax were formed 

 from " stipules," so we perceive in the Acacias how these latter 

 organs may be altered to form the " spines," or " prickles," of these 

 plants. 



Passing from leaves and flowers to fruits, we enter a new but 

 equally interesting field of speculation with the last. Let us firstly 

 inquire what is the nature of the structure to which the botanist 

 gives the name of " fruit." It is perfectly evident from the common 

 knowledge of Nature's processes which ordinary observation affords 

 that the fruit is merely part of the flower. The buds of springtime 

 and the blossoms of summer must precede the fruit of the autumn ; 

 and the promise of " a golden reaping " is heralded by the early 

 growth of the vernal season. Without the flower, then, the fruit 

 would be non-existent, and considering that within the vast majority 

 of fruits we find the seeds, we can readily construct a definition of 

 the botanical fruit by defining it as " the ripe pistil." Such is the 

 invariable nature of the fruit in the mind of the botanist. Popu- 

 larly, however, "fruits." are only to be so called when they are 

 edible. The mental and scientific concept of the man of science 

 vanishes before the practical matter-of-fact definition of a fruit as 

 that which is good to eat ; and perhaps each definition meets in 

 its own way the exigencies and circumstances which called it forth. 



But the study of fruits from the botanical side, presents us with a 

 highly interesting illustration of the value of " homology," as showing 



