ADDENDA TO BOOKS I. AND II. 567 



c. 



CONTAINING THE NEW PASSAGES IN THE THIRD GERMAN 

 EDITION OF THE FIRST AND SECOND BOOKS: Leipsic, 1849. 



Page 18., fourth line from the bottom. 



Development of the Starch Granule. In very young potatoes we 

 find exceedingly minute granules ; in general, a greater number of small 

 than of large ones : even in the cells of .old potatoes minute granules 

 occur, mingled with the larger. If we regard the very minute granules 

 as the rudiments of the structure, and take the different size as standard 

 for estimating the age, the result is as follows : the smaller (therefore 

 the younger) the granules are, the more truly spherical they appear, and 

 the ovate or irregular outline is subsequently acquired. It is easy to 

 see that this deviation from the original globular form is not caused by 

 internal layers, but by the outer, the unequal thickness of which pro- 

 duces the gradual alteration of the outline ; while the innermost layers 

 continue to exhibit the form (spherical) which the youngest, that is, the 

 most minute, granules present. The conclusion from this is, that the 

 outermost layers are the youngest, and the innermost the oldest ; that is 

 to say, the starch grows by the successive deposition of new layers upon 

 the older. The probability deduced from the investigation of the potato 

 becomes almost certainty when we compare the starch granules in the 

 tuberous stem of Bletia TankerviUuB, in the rhizome of Lathrcea squa- 

 maria, and in the stem of Dieffenbachia seguine. In Bletia, by far 

 the greater part of the granules have a most characteristic outline, easy 

 to be detected ; and the structure of the layers is equally peculiar. 

 Others are enclosed by additional layers of a totally different shape, 

 laterally excentric from the former ; arid it is almost impossible to refuse 

 the conviction that the outer layers are the last formed. The same 

 holds good of Dieffenbachia^ only the granules are here more difficult to 

 observe. Fritsche arrived at the same conclusion from the consideration 

 of the "twin-granules," enclosed by simple outer layers ; and most 

 observers have since maintained it. The only other views are the base- 

 less and daring speculations of, in some cases, most superficial observers : 

 these require no refutation, since they are not supported even by an 

 appearance of probability. 



Page 23. 10. 



The author adopts the term protoplasma, proposed by Mohl, in the 

 place of mucus (schleim), the name formerly given to the quaternary 

 and proteine compounds, and which has been adopted in this transla- 

 tion. 



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