from Botanical and Economic Aspects. 229 



that mere lateness of ripening need not indicate a poor or 

 primitive fruit. The small amount of the fruit pulp and the 

 small size of the seeds in specimen I, are additional proofs, 

 that this is a primitive form, rather than a degraded one. 



Until better and more conclusive evidence is obtained, we 

 may accept the above as probable, and now try to determine 

 the cause or causes for the origin of the varieties. It deserves 

 to be emphasized, that most of our cultivated plums, and also 

 the sand cherry as well as the beach plum, show fruit and 

 seed variations exactly along the lines of those now described. 

 This might indicate that all of these are comparatively recent- 

 evolutions from a common stock that acquired these varietal 

 variations and then branched off into specific lines of develop- 

 ment in stem, leaf and flower, without losing the fruit and 

 seed variations already acquired in common. From a primi- 

 tive small, hard, semi-succulent, purplish green, late-maturing 

 type like No. I, we might have in each of the specific groups, 

 lines of variation passing from it to greenish purple, to purple, 

 purplish blue and blue black. Or again from the same start- 

 ing point we might obtain, by predominence of acid cell 

 contents, greenish red, red, reddish-yellow, to yellow. 



As to the possible cause for the origin of these varieties, the 

 writer has nothing of value to suggest. Some suggestions 

 may, however, be offered. Thus when study of all the 

 environmental conditions is made, it is seen that these plants 

 usually grow where alteratio'ns in the relations of sea and land 

 are frequent. The varieties of sub-soil also vary considerably, 

 and may affect the plants, according to the heaviness or 

 porosity of it. The relative amount of the halogen compounds 

 in the soil round a plant or plant group, may likewise have 

 a determining effect. Exposure to a bright, hot sun, or 

 protection in comparative shade may also have been a deter- 

 mining factor. A fruitful field for observation and experiment 

 is open here as in many other fields, and suggests to us the 



