180 THE MICROSCOPE. 



attempt to set up as fixed laws what are merely the ex- 

 pressions of the present state of our knowledge, or to wish 

 to throw discredit on the observations of accomplished 

 and careful microscopists, merely because they overthrow 

 distinctions which I had imagined to be well founded. 

 J would strongly recommend the observations of Professor 

 Hartig (Quart. Journ. of Microsc. Science, vol. iv., p. 51) 

 and of Mr. Carter (Ann. of Nat. Hist., Feb., 1856) to your 

 attentive scrutiny." 



As we pass on to a more intimate examination of the 

 various structures entering into a plant, it will be seen 

 that we have objects of the deepest interest presented to 

 our notice ; and strikingly differing as we find plants and 

 animals in some essentials, we shall here, at our starting- 

 point, find them gradually coalescing, until they meet in 

 a common granule "that of the simple and individual 

 cell." 



Miilder, in describing this starting-point of life, says : 

 " The cell is a concave globule. This concave globule is 

 an individual; in the most simple form in which it can 

 possibly exist (in the lowest moulds), it possesses all the 

 powers of the molecules united into one whole, and thus 

 reduced to a state of equilibrium. This state depends, 

 not only on the nature of the substances and of their 

 elements, carbon, hydrogen, oxygen, and nitrogen, but also 

 on their form. The state of equilibrium, therefore, could 

 not exist, unless this concave globular form existed. More- 

 over, this hollow globule possesses the whole of these forces 

 in a state of mutual combination, co-operating for one end ; 

 this being a peculiarity which also apparently depends on 

 the globular form." 



Cells from which plants are formed are very small deli- 

 cate closed sacs, partaking of many forms, and enclosed in 

 a perfectly transparent membrane, so excessively thin, that 

 it is with difficulty detected, unless iodine or some colour- 

 ing-matter be previously added. Dead and old cells form 

 an exception, as they become thickened, and the broken 

 surfaces are then readily detected. At one time the cells 

 were said to be developed by an extrication of gaseous 

 matter among mucus; but the double walls which separate 

 cells are irreconcilable with such an origin. Mr. Thwaites 



