194 Linnaan Society. 



those substances are generally situated, and found that their forma- 

 tion took place, in the majority of instances, in the following manner. 



In the very young stem of Circcea Lutetiana, or the young branch 

 of the Grape- Vine, the different appearances presented by the grains 

 of starch from their perfect state down to their first commencement 

 may be readily observed by making numerous sections from the 

 lowermost internode up to the terminal joint. The cells most re- 

 cently formed are so filled with mucilage and granules as to be opake ; 

 lower down the granules begin to disappear and the cytoblast is ap- 

 parent ; still lower the cytoblast appears to have lost its granular 

 character without having much increased in size, and has become a 

 minute cell with a distinct nucleus, instead of a congeries of gra- 

 nules with a larger central one. On the outside of this nucleated 

 cell, granules (varying in number from ten to twenty) make their 

 appearance, at first very minute and of a green hue, and afterwards 

 enlarging and becoming colourless ; and as they increase in size the 

 nucleated cell is absorbed and the granules become free. At a later 

 period a multiplication of the granules takes place by fission and 

 pullulation, certain grains exhibiting marks of subdivision, and 

 others having minute granules attached to them; and generally 

 nwe grains of starch are found in a cell than the number of minute 

 granules seen developing on the nucleus. 



Several of these stages are more readily seen in the tuber of the 

 Potato. If a slice be removed from its exterior so thin as only to 

 pass beneath the cuticle, and a very thin and perfectly transparent 

 slice be then taken and examined under the microscope, the cells in 

 the central portion are seen to contain only a few grains of starch, 

 while in approaching the sides of the section the grains become 

 smaller and pass gradually into the nature of chlorophylle. On di- 

 recting attention to those parts of the section, in which the cell- 

 contents pass gradually from the state of starch to that of chloro- 

 phylle, many cells are seen to contain a distinct nucleated cell, ap- 

 parently of a flattened or lenticular form, on the edge of which are 

 arranged a number of minute granules ; in others the appearances 

 are more advanced, the granules gradually becoming larger and the 

 nucleated cell becoming obliterated. From the disturbance that 

 takes place in the position of the granules after detachment from the 

 nucleated cell, it is difficult to determine by what part they were 

 adherent to it ; but Mr. Quekett believes that this adherence takes 

 place at the end at which the point or hilum is observed. Subse- 

 quent to this period the grains of starch enlarge, become laminated, 

 and are multiplied in the manner already pointed out by various 

 observers. 



Such are the results of Mr. Quekett's observations on Exogenous 

 plants ; in Endogenous plants he states that the same process does 

 not appear to be in all cases pursued, inasmuch as while the rhizoma 

 of Iris germanica affords a favourable example for the exhibition of 

 the process as above described, the young stem of Lilium bulbiferum 

 offers the following differences. Sections taken from the base of a 

 young stem within the bulb have their cells full of starch-grains ; at 



