THE PLANT-CELL. 23 



continuity of the protoplasm of the cells of the row can be 

 readily observed ; in the case of the vessels of the wood and 

 of the laticiferous vessels, the separating walls have been 

 entirely absorbed, so that these structures are spoken of as 

 cell-fiisions. Even in parenchymatous cells a communication 

 of the protoplasm of adjoining cells has been observed ; by 

 Tangl, for instance, in the endosperm of certain seeds, by 

 Gardiner, in the contractile organ at the base of the petiole N 

 of Mimosa, and .by Frommann in epidermal cells. It is 

 probable that this is the case far more commonly than is 

 usually supposed, for the walls of most parenchymatous cells, 

 when treated with appropriate reagents (potash or Schultz's 

 solution), shew what are apparently thinner areas, (pits) 

 through which the protoplasmic filaments might be supposed 

 to pass. 



The Protoplasm. 



The protoplasm of the cell under consideration (Fig. 3) 

 forms, as has already been pointed out, a layer, formerly 

 termed the primordial utricle, which closely lines the cell-wall, 

 and which is connected by means of bridles with a mass 

 towards the middle of the cell in which the nucleus is im- 

 bedded. Careful examination of the peripheral layer shews 

 that it consists of two layers, an outer hyaline and firm, in 

 close contact with the cell-wall, an inner granular and some- 

 what fluid ; the former may be distinguished as the ectoplasm 

 (Jiautschicht), the latter as the endoplasm. The granular ap- 

 pearance of the endoplasm is due to the presence of minute 

 solid particles of organic and inorganic substances, drops of 

 oil, etc., which may be distinguished from the protoplasm itself 

 as metaplasm (Hanstein), and also to the presence of minute 

 corpuscles, termed microsomata, which are probably to be 

 regarded as part of the protoplasm. Very commonly the 

 endoplasm is bounded towards the vacuole by a hyaline firm 

 layer resembling the ectoplasm which bounds it towards the 

 cell-wall. 



This distinction of layers is all that can be made out as to 

 the structure of the protoplasm when the cell is examined 



