60 
Busk on Starch- Cfranules. 
nature from the layers around it (Fritsche), or not essentially 
different in that respect (Endlicher and Unger). Schleiden, 
on the other hand, and many other observers, look upon the 
supposed nucleus as a minute cavity or indentation. Dr. A. 
Braun (/. c), however, supposes that this cavity does not exist 
originally in the granule, but that it is of a secondary nature, 
arising in the disappearance of the nucleus. 
The laminated, or supposed laminated, appearance evident 
in many forms of starch, and demonstrable perhaps in many 
others by means of polarized light, has been variously explained 
according to the above views of the essential constitution of 
the granules. 
In accordance with the former of these views, Miinter,* 
Nageli,! and Link, suppose that the laminae are formed by an 
internal or centripetal deposition of matter in the interior of 
the cell, and, according to the latter, this deposition is con- 
ceived to take place from without, or, as it may be expressed, 
centrifugally. This notion appears to be that more generally 
adopted. Originally propounded by Fritsche, it is followed 
by Schleiden, and, more recently also, though with some hesi- 
tation, by Dr. A. Braun (/. c.) who considers it as much more 
probable than that advocated by Miinter and Nageli, if the 
starch-grains are not themselves cells, but merely the product 
of secretion from the cell-contents, in the same way as the cell- - 
membrane is, with which the starch is so closely allied. The 
same view is also adopted by FockeJ and Schacht.§ 
The above is a very brief and imperfect summary of the 
views more generally entertained on the structure of starch, 
and, omitting all reference to what has been written respecting 
its mode of origin (which, in fact, amounts to little) and its 
use in the vegetable economy, I will now proceed to notice 
what may be termed a modification of the former of the above 
described views, or of that which assigns a cellular structure 
to the starch-granule, and the reception of which I am greatly 
inclined, from my own observations, to advocate. 
Leeuwenhoeck, II to whom we are indebted for the earliest 
notice of starch-granules, enters with considerable minuteness 
into a description of those of several plants, such as wheat, 
barley, rye, oats, peas, beans, kidney beans, buckwheat, maize, 
and rice, and very distinctly describes experiments made by 
* Miinter, ' Uh. das Amylon der Gloriosa siiperba,' &c. (' Bot. Zeit.' 
1845, p. 198.) 
t Nageh, ' Zeitschrift.' 1847, p. 117. 
X Focke, ' Die Krankheit der Kartoffeln.' Taf. ii. fig. 13, f. g. h. 
§ Schacht, ' Die Pflanzenzelle.' 1S52, p. 41. 
II Leeuwenhoeck, ' Epistolge Physiologicse,' &c. Delphis. 1719, p. 236. 
