78 SCIENCE PROGRESS. 



one, starch granules appear as before, and, growing, be- 

 come pressed together till the whole vacuole is full. The 

 new grains appear consequently compound on account of 

 the new fine network which separated the seats of com- 

 mencement of formation of the grains. Belzung concludes 

 that Schimper's leucoplasts are nothing more than cavities 

 in the protoplasm, which become filled with starch by the 

 action of the bounding layer of the former. 



Schimper states that the grains which are situated deep 

 in the chloroplasts have a concentric striation, while those 

 which are formed near their surface are excentrically 

 striated, and he attributes the phenomena to the relation 

 of the grain to the substance of the plastid. Belzung con- 

 tends, on the contrary, that while the starch grain is in 

 the chloroplast no striation can be seen, but after it escapes 

 from the plastid it becomes striated. The escape of the 

 starch grain from the latter can be seen best in those 

 cases where its origin is near the surface of the plastid, and 

 not in its centre. 



Eberdt (29) partly supports Belzung's views, but puts 

 forward a new interpretation of the appearance of the 

 leucoplast. He says that the growth of an excentrically 

 striated starch grain is not due to the action of any unilaterally 

 attached body such as a plastid ; both the excentric and the 

 concentric ones can be seen to grow in the cell-sap by the 

 action of the protoplasm. In the case of the grains formed 

 in connection with the chloroplasts he observes the same 

 thing, the grain growing after the chloroplast has dis- 

 appeared, and being nourished or added to by the proto- 

 plasm, wherever the latter is in contact with it. He suggests 

 that the development of the starch grain has two phases, 

 it being originated by the chloroplast, and then later built 

 up by the protoplasm. The striation he holds to be due 

 to intussusception, and not to apposition at all. 



In the formation of the starch grains in relation to 

 leucoplasts Eberdt thinks the latter is not a plastid in the 

 sense of constructing the grain, but is rather a formative 

 material or fundamental substance which becomes trans- 

 formed into the substance of the starch grain. The so- 



