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ration remain quiescent until the coast is clear for another 

 vear of si^owth. The inherent tendency of one introduced 

 variety of plant to start into growth before another may 

 throw it into the class called tender, while another with the 

 same structure, but differently disposed, will prove hardy. 

 The test for sugar in the late winter may aid in deciding 

 that a difference in this tendency exists, for starch, the chief 

 form in which the carbohydrates are stored up in many kinds 

 of twigs, is changed into sugar before it becomes available for 

 plant nutrition. 



Crystals, — A few words concerning these structures, w^hich 

 were constantly met with in all buds examined, will be suffi- 

 cient for this portion of the subject. Vegetable physiologists 

 are agreed that true crystals (not including crystalloids) in the 

 tissue of plants are a form of refuse, or left-over matter, re- 

 sulting from the processes of growth, and put up in a consoli- 

 dated form, to get them as much out of the w^ay as possible. 

 Some one has compared them to the pieces of brick, mortar 

 and other material thrown into boxes and barrels during the 

 construction or repair of a building. Crystals were rarely 

 found in the old pith, and have not been seen in the wood, but 

 are very abundant just below the growing tips of all buds in 

 that cylinder of tissue connecting the free extremity of the 

 bud w^ith the starch-bearing cells — a half-inch or so back of 

 the tip. The loose green bark of all parts of the twigs also 

 abounds in these bodies, and they are especially numerous in 

 the cellular tissue that lies between the leaf scar and the bud 

 above it. In this locality, a second form is often met with, 

 wdiich is smaller and rectangular in shape, while the prevail- 

 ing sort is an irregularly spherical aggregation of sharp- 

 angled bodies, which have taken the name of sphaero-crystals. 

 These crystals are composed of oxalate of lime (calcium ox- 

 alate) and may be dissolved by mineral acids. 



From the composition of these bodies, their universal 

 prevalence in about equal numbers, first in proximity to tis- 

 sues which are the centers of rapid vital processes, and sec- 

 ondly, in out-ol-t he-way places, and for various other reasons, 

 it is safe to conclude that crystals are no safe criterion by 

 which to judge of the relative resisting powers of plants to 



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