130 Flowers and their Pedigrees. 



pose that the calyx hairs followed suit with the stem 

 hairs, and began to develop into stiff prickles, in 

 order to understand how the burrlike mechanism was 

 first set up. Supposin^j it once begun, in ever so 

 slight a degree, every little burr which succeeded in 

 sticking to a sheep's legs or a small bird's breast 

 would be pretty sure, sooner or later, of reaching a 

 place where its seeds could live and thrive. It is 

 from this habit of cleaving or sticking to one's legs 

 that the plant has obtained one of its English names 

 — cleavers. Moreover, to make the development of 

 the burr all the more comprehensible, many of the 

 other galiums have rather rough or granulated fruits, 

 while one kind — the wall galium — which in England 

 has smooth or warty fruit, has its surface covered in 

 southern Europe with stiff hairs or bristles. Another 

 English galium besides goose-grass has hooked bristles 

 on its fruit, though they are not so hard or adhesive as 

 in our own proper subject. Thus the verx* steps in the 

 evolution of the bristly fruit are clearly preser\'ed for 

 us to the present day in one or other of the allied species. 

 On the other hand, the ver\' similar little corn 

 galium, which has prickles on its stem and leaves to 

 enable it to cling to the growing straw in the wheat- 

 fields, has no hooks at all upon its fruit. Instead of 

 a burr it produces only little rough-looking knobs or 



