24 ELEMENTS OF PLANT ANATOMY. 
1. Cytoplasm. 
When closely examined this appears to contain fine grains, 
much smaller than the structures just described and having the 
nature of proteids. They are imbedded in a clear, hyaline 
substance, and are unequally distributed, occurring in greater 
numbers near the central part of the cytoplasm ; the outer part 
or that lying near the cell wall is nearly clear. Some botanists 
believe that this granulated appearance of the cytoplasm indi- 
cates a definite structure similar to that known to exist in the 
animal cell. They claim that the apparent grains are really 
not grains, but very slender fibers running through the hyaline 
substance with some fixed order of arrangement. No definite 
proof of this has yet been found. According to the amount of 
water contained in it, the cytoplasm forms a more or less tena- 
cious, mucilaginous mass in which the single particles or 
granules may easily move. The chief constituents of this mass 
are known to be of proteid nature, but their exact chemical 
composition has not yet been determined. ‘The elements are 
carbon, hydrogen, oxygen, nitrogen, and sulphur and _ phos- 
phorus, the last two in small quantities, but in what propor- 
tions their atoms unite to form a molecule is not known. The 
many experiments that have been tried to determine this have 
succeeded only in establishing a probability that very complex 
chemical compounds are present; thus rendering possible a 
large number of different organic combinations on the dissocia- 
tion of these compounds. 
This mass of cytoplasmic substance is flexible, slightly 
elastic, and rich in colloidal substances, which in order to 
become diffusible must be changed into other nitrogenous com- 
pounds named amides, of which mention will again be made. 
When living, it is almost impenetrable for salts and coloring 
matters, but when dead this property is lost. 
The power of motion residing in vegetable protoplasm is of 
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