24 



exterior, and has the starch-bearing pith extending for a half 

 of the way, from the base to the sharp, hard tip. In the 

 main twig there is a manifest accumulation of starch at the 

 base of the spine, as is shown in figure 15. Figure 16 shows 

 a fruit-spur, the center of which is filled with starch for the 

 purpose of providing abundant nourishment for the develop- 

 ment of the cluster of flowers. 



Many other examples might be cited, but that of the 

 Japan quince {Cydonia Japonica^ Pers.) will suffice. The spines 

 of this favorite hedge plant were examined in February, while 



some of the blossoms had already expanded, due to the very 

 warm winter of 'Sq-'qo. The position and relative size of the 

 parts are shown in figure 17. It will be seen that the flower-stem 

 is short, and the spine joins it at the base. In figure 18 the 

 condition of the starch storaije becomes clear. There is no 

 starcli in the flower-spur, but an abundance in the interior of 

 the spine, to be withdrawn to feed the flower and the leaves 



#- 



that afterward come upon the stem. 



It is very likely that the spines are primarily for the 

 warding off of enemies, but if we can look upon the protective 

 organs as serving another purpose it adds further dignity to 

 the police department, so to speak, of the plant. 



METHODS AND REAGENTS. 



r 



Starch. — For the detection of starch, as before stated, the 

 solution used was iodine made as follows; three grammes of 

 crystallized potassium iodide were dissolved in sixty c. c. of 

 distilled water, to which was added afterward one gramme of 

 metallic iodine. This solution was diluted as the occasion 

 required. The microscopic inspection for starch was with 

 thin sections either treated at once with the iodine solution 

 or after they had received potassic hydrate to remove the 

 protein compounds that might otherwise obscure the reaction. 

 When the presence of starch was established its abundance 

 and general distribution was determined by splitting the bud 

 or twig, or both, and immersing the parts, for a few minutes 

 in a long porcelain trough, when the degree of darkening of 

 the various parts of the section gave the amount of starch 



