189G.] ^^'^ [Bailey. 



passed their zenith, as the cucurbits, composites, begouias and the lilve. 

 The varieties of cereals, which are old types, are so much alike that expert 

 knowledge is needed to distinguish them. 



5. New types are more variable and flexible because less perfectly 

 moulded into and adjusted to the circumstances of life than the old types 

 are. They have not yet reached the limits of their dissemination and 

 variation. They are generalized forms. 



The reader will please observe that I have here regarded the origin and 

 survival of the unlike in the plant creation in the sense of a plastic 

 material which is acted upon by every external stimulus and which must 

 necessarily vary from the very force of its acquired power of growth, and 

 the unlikenesses are preserved because they are unlike. I have no sym- 

 pathy with the too prevalent idea that all the attributes of plants are direct 

 adaptations or that they are developed as mere protections from environ- 

 ment and associates. There is a type of popular writings which attempts 

 to evolve many of the forms of plants as a mere protection from assumed 

 enemies. Perhaps the plant features which have been most abused in 

 this manner, are the spines, prickles and the like, and the presence of 

 acrid or poisonous qualities. As a sample of this type of writing, I will 

 make an extract from Massee's Plant World : 



"Amongst the most prominent and general modes of protection of 

 vegetative parts against the attacks of living enemies may be mentioned 

 prickles, as in roses and brambles, which may either be straight, and thus 

 prevent the nibblings of animals, or, in more advanced species, curved, 

 thus enabling the weak stem to climb and carry its leaves out of harm's 

 way. Spines, that are sharp-pointed abortive branches, serving the same 

 purpose as prickles, as in the common sloe or blackthorn (Prunus spinosa). 

 Rigid hairs on leaves and stem, as in the borage {Borago officinalis), and 

 comfrey {Symphytum officinale). Stinging Jiairs, as in the common net- 

 tles {Urtica dioica, and TJ. urens). In these cases the stinging hairs are 

 mixed on the leaves and stem with ordinary rigid hairs, of which they 

 are higher developments, distinguished by the lower or basal swollen 

 portion of the hair containing an irritating liquid that is ejected wlien the 

 tip of the hair is broken off. Bitter taste, often accompanied by a strong 

 scent, as in wormwood (Artemisia vulgaris), chamomile {Anthemis nohilis), 

 and the leaves and fruit of the walnut (Juglans regia). Poisonous alka- 

 loids, as in the species of Strychnos, which contain two very poisonous 

 alkaloids, strychnine and brucine, in the root and the seeds ; decoctions 

 of species of Strychnos are used by the Javanese and the natives of South 

 America to poison their arrows. Some of the species, as Strychnos nux- 

 vomica, are valuable medicines, depending on the strychnine they contain, 

 which acts as a powerful excitant of the spiijal cord and nerves ; thus the 

 most effective protective arrangements evolved by plants can be turned 

 to account, and consequently lead to the destruction of the individuals 

 they were designed to protect. Our common arum (Arum maculat2im), 

 popularly known as 'Lords and Ladies,' has an intensely acrid sub- 



