332 Meyen's Report for 1839 on Physiological Botany. 



roots which contain within this hardened mucilage a large 

 quantity of starch, for the whole substance is coloured violet 

 by iodine, and indeed throughout the whole mass, which does 

 not accord with Lindley^s observations. All the cells are filled 

 with balls of tragacanth gum ; some of them are ten or fifteen 

 times larger than the neighbouring ones, but there are no 

 cells which contain solely amylum grains ; but out of a great 

 number of sections, single large gum nodules may be found, in 

 which the globules, similar to those of starch, may be easily 

 distinguished lying round the old nucleus in the interior of 

 the nodule. 



Very remarkable is the fact, that most of the walls of these 

 large cells containing gum appear as if composed of smaller 

 cells, by which these membranes often assume a very beautiful 

 appearance ; on closer examination I found that this apparent 

 net of cells consisted of superficial deposits, similar to the cell- 

 like formations on the surface of pollen grains. Even in very 

 young tubers traces of these formations may be seen on the 

 inner surface of the membranes of those large parenchym cells 

 which are rich in gum. 



M. E. Meyer* read a paper to the Physico-CEconomic So- 

 ciety of Konigsberg on the 18th of September, 1839, on amy- 

 lum, in which he explains fully the appearance and structure 

 of the amylum grains according to former observations, and 

 mentions their use ; he, however, incorrectly states that it is 

 not yet clearly determined whether the layers of the globules 

 are deposited from without, for the genesis of the globules 

 with which we are acquainted shows this quite clearly. M. 

 Meyer communicates an interesting fact, viz. that in the 

 summer of 1838, on account of the excessive moisture in that 

 part of the country, that rare malformation, the production 

 of tubers on the parts of the potatoe plant which are in the 

 air, was very abundant ; this malformation extended itself over 

 whole fields, and M. Meyer saw some specimens which were 

 covered to the top with tuberculous swollen sprouts, and were 

 partly covered with real tubers. The statement, that potatoes 

 possess the largest grains of starch yet known, is probably 

 only a slip of the pen ; but it is a curious statement, that the 

 pith of plants never contains amylum, as also that the stems 

 of Palms and Cycadece never have pith, whence it would re- 

 sult that sago could not be prepared from their pith. 



M. Fr. Tornabene Casineset has written a treatise on the 



* Frorieps Neue Notizen, Nos. 253, 254, Nov. 1839. 

 f Sull'humore crystallino nelle foglie seminali delle piante. Memoria sopra 

 alcuni fatti di anatoraia e fisiologia vegetalc. Catania, 1838. 4to, p. 3 — 28. 



