Vegetable PInjsiologij. 403 



The presence of this formative protoplasm is evident in the 

 starch-cells of the potato after they have been boiled. If a por- 

 tion of the " floury " substance is placed under the microscope, 

 it will be seen that the cells have becoine separated from each 

 other, and that they are also swollen from the softening and ex- 

 pansion of the starch-granules. On the membranous walls of 

 the cells will further be perceived reticulated lines, which are the 

 coagulated remains of the protoplasm which intervened between 

 the granules. With iodine these assume a yellow colour. 



The connexion existing between the starch-granules and chlo- 

 rophyll has already been noticed. Some of the more important 

 features of their relations will now have become evident from 

 what has been stated above respecting, on the one hand, the true 

 nature of the chlorophyll, the fact especially of its having a basis 

 of protoplasm or albuminous matter, — and, on the other, of the 

 origin of starch-granules from a matrix of the same or similar 

 material. 



Chlor-ophyll-granules are found in all the vegetating organs of 

 green plants, at some period of growth, having one or more small 

 starch-granules in their interior. The size of the starch-granules, 

 in comparison with that of the chlorophyll-granule containing 

 them, varies extremely ; sometimes the starch appears as one or 

 more bright points in the substance (coloured blue when treated 

 with iodine), sometimes the single starch-granule, or a confluent 

 group of granules, appears surrounded by a mere film of chloro- 

 phyll (fig. 17). These differences of size are shown, by compa- 

 rative observations on the same plant, to depend upon the age, 

 that is, the degree of development, of the starch-granules ; they 

 grow up from an almost invisible point in the interior of the sub- 

 stance of the chlorophyll, just as free starch-granules do in the 

 colourless protoplasm of seeds, tubers, &c. Chlorophyll-granules 

 containing starch-granules are very well seen in many of the 

 lower plants, as in the leaves of Mosses and Liverworts, especi- 

 ally in spring (fig. 17). Largish granules also occur imbedded 

 in the bands of Spirof/yra (fig. 10, A, h), and they occur 

 abundantly during active vegetation in the green protoplasmic 

 contents of the Confervoid Alga? generally. The closely-packed 

 layer of chlorophyll in Chain has the granules sometimes so 

 loaded with starch, that they form a dirty- blue layer when iodine 

 is applied. In the higher plants the chlorophyll-granules of the 

 deeper-seated tissues of green organs, as the middle substance of 

 leaves, and the cells of the rind nearest the wood, present starch- 

 granules more frequently than those in cells lying immediately 

 beneath the epidermis. 



It is observed that, generally speaking, the substance of chlo- 

 rophyll-granules which contain starch is of denser consistence ; it 



