M. H. V. Mohl on the Structure of Chlorophyll. 425 



which the starchy nucleus forms the greatest part of the whole 

 grain, and has a diameter of from 2^uo ^^ Ts^uu ^^ ^ ^^^^- -^^ 

 the outer leaves of the hud, grown up to a length of 7 lines, the 

 starch had vanished from the chlorophyll-globules, and the 

 latter had attained a size of j^^ of a line. Their development 

 however was not complete here, for although the starch had dis- 

 appeared, the chlorophyll-globules still exhibited increase, and 

 in the full-grown leaves had reached ^jq of a line. Moreover 

 there is certainly no general rule that starch decreases in size or 

 becomes entirely absorbed with the development of the chlo- 

 rophyll, for, on the contrary, it is quite as common to find that 

 the starch-grains situated in the chlorophyll are extremely small 

 in young leaves, and increase in size with the chlorophyll-globules, 

 and indeed in comparatively greater degree, so that in the young 

 chlorophyll-globules the green envelope is proportionately far 

 thicker than it is in the full-grown mass ; as occurs, for example, 

 most distinctly in Ceratophyllum. 



Gathering all these points together, — the occurrence of chlo- 

 rophyll in cells which contained no starch ; the occurrence of 

 membrane-like chlorophyll-structures not preceded by any cor- 

 responding starch-structure or accumulations of starch-grains ; 

 the growth of chlorophyll-globules after the starch-grains have 

 vanished from them ; the simultaneous increase in size of starch 

 and chlorophyll-globules in other plants; — we are necessarily 

 led to the conclusion, that chlorophyll is not produced by the 

 transformation of starch-grains, but that the two structures, 

 though frequently connected together, originate independently 

 of each other. The starch may exist earlier, and the chlorophyll 

 accumulate around the starch-grains as around a nucleus — as 

 may be seen so clearly in the internal, starch-bearing cells of a 

 potato when exposed to the light, and, in extremely numerous 

 cases, in the leaves of buds ; and, on the contrary, the starch- 

 grains lying in chlorophyll-globules may increase in size inde- 

 pendently, and even be formed in chlorophyll which originally 

 contained no starch. 



December 1854. 



[My own observations fully confirm the statement that starch- 

 grains may originate in chlorophyll-globules at first totally de- 

 void of starch ; I have traced the formation of groups of starch- 

 grains in this way in the interior of chlorophyll in the Hepaticae 

 and other Cryptogamous plants. There can be little doubt that 

 the chlorophyll belongs to the protoplasmic substances of the 

 cell-contents, and is capable of producing starch equally with 

 the colourless protoplasm. From the mode in which starch- 



Ann.^ Mag. N. Hist. Ser.2. Vol.xv. 28 



