STRUCTURE.] SITUATED WITHIN CELLS. 103 



of the vegetable kingdom seems without greater or smaller 

 quantities of these crystalline formations, which are found in 

 a great number of Exogens and Endogens, and likewise in 

 Acrogens, being visible in Ferns and Mosses, and, according 

 to linger, in the lowest of the Algacese, as Nostoc Muscorum, 

 and Conferva crystallifera. 



The frequency of occurrence of these bodies is such, that 

 it appears that, instead of those plants containing them being 

 exceptions, those are to be considered such which have none 

 in their tissues. 



It does not appear, from numerous observations, that the 

 acicular and conglomerate Raphides are equally common 

 in the several classes of Plants ; but that Exogens contain 

 perhaps the one kind as often as the other, while Endogens 

 undoubtedly contain most often the acicular variety. 



Situation. The position of these bodies has been a sub- 

 ject of controversy ; Raspail asserting that they are always 

 in the intercellular passages, whilst Turpin, Meyen, and 

 linger maintain that they are universally in the interior of the 

 cells, which latter opinion is easily proved to be nearly correct 

 by a little careful dissection of any plant containing them. 



RaspaiFs advice to see these bodies is to tear a piece of 

 the Hyacinth stem in a drop of water placed on the stage of 

 the microscope, when numbers of acicular crystals will be 

 visible (this method is not likely to show them in the interior 

 of the cells) ; and from measuring he finds the length of the 

 crystal longer than the ordinary cells of the tissue ; and 

 therefore he decides from this, that they cannot be contained 

 in the interior of the cells, while he overlooks the fact that 

 the cell in which they are contained may be often dilated to 

 five or six times the size of those composing the ordinary 

 tissue of the plant. The square crystals in Quillaja saponaria 

 appear as if loose in the plant, but they are really in a cell, 

 which cell is applied closely to the surface, the crystal com- 

 pletely filling it : when muriatic acid is added the crystal is 

 dissolved, and the cell is left visible. 



The most ready method of determining that the acicular 

 crystals are contained within the cells is, to take a piece of 

 the bulb of Scilla maritima and macerate it until it becomes 



