Autonomy of Chromoplasts 147 



their shape considerably, and with it the structure and size 

 of the starch-grains produced by them. 



Among the most peculiar characters of the chromato- 

 phores in connection with the organization of the proto- 

 plasts, belong their autonomous movements. Since the 

 researches of Sachs on this subject, we know that the 

 chlorophyll grains of some plants are moved about by 

 streams of the granular plasm in such a way that, under 

 the influence of light, they take up positions which are 

 favorable for the assimilation of carbon dioxide. But in 

 this process they are passive. The beautiful researches of 

 Stahl, however, have disclosed independent movements 

 of these structures under the influence of the same stimu- 

 lation. They consist chiefly in changes of shape, through 

 which the organs in question either approach a more or 

 less globular shape, or that of a flat, circular disc. Thus 

 it is brought about that, in direct sunlight, they present 

 a smaller, in diffuse daylight, a larger surface for re- 

 ceiving the rays. And to us they afford an insight into 

 the high degree of their inner differentiation such as we 

 could never have attained by the simpler study of their 

 chemical activity. 



According to Weiss, the yellow and orange chromo- 

 plasts at times also make autonomous movements, which, 

 according to the descriptions of this author, resemble the 

 changes of form of the amoeba and the white blood-cor- 

 puscles. 37 These structures, therefore, may also be more 

 highly organized, and play a more important role, than 

 that of the simple task of giving their color to the respec- 

 tive plants. 



I wish to lay quite particular stress here on these 



87 Weiss, A. Ueber spontane Bewegungen und Formanderungen 

 von Farbstoffkorpern. Sitzungsb. Kais. Akad. Wiss. Wien. 90: 1884. 



