40 MORPHOLOGY OF THE CELL. 



of a beautiful dark violet. Protoplasm containing but little water treated with a 

 large quantity of concentrated sulphuric acid assumes a beautiful rose-red colour, 

 without at first changing its form; subsequently this colour and the form disappear 

 together, the protoplasm dissolving. Dilute potash solution (sometimes also ammonia 

 solution) dissolves protoplasm, or at least destroys its form, and makes it homogeneously 

 transparent. If, on the other hand, cells with protoplasm of characteristic form are 

 placed in concentrated potash solution, the form remains for weeks, but disappears 

 immediately on addition of water. All these reactions are collectively characteristic of 

 true albuminoids, as casein, fibrin, and albumen;^ and we are therefore justified in 

 assuming that substances of this kind are always contained in protoplasm. If the 

 protoplasm-sac in cells with much sap is very thin, it acquires a greater power of 

 resistance to the solvents. In another respect also protoplasm behaves like albuminoids. 

 By heating very watery protoplasm to above 50° C, it is killed and becomes turbid 

 and stiff, as if coagulated ; alcohol and dilute mineral acids act in the same manner. 

 The nucleus behaves towards all colouring substances, solvents, and coagulating agents, 

 in the same manner as living watery protoplasm, or it shows itself even more sensitive, 

 especially in young cells ; in older cells however it is acted on less easily. 



At the base of all protoplasmic structures there probably lies a substance which is 

 colourless, homogeneous, and not visibly granular, to which alone the name Protoplasm 

 ought perhaps to ba applied, or which ought at all events to be distinguished as the 

 basis of protoplasm. The fine granules which are so often mingled with it. and 

 whic'.i some consider an essential ingredient, are probably finely divided assimilated 

 foDl-materials, which undergo a further chemical metamorphosis into protoplasm; every 

 intermediate form occurs from these more or less fine granules to the largest which 

 may be clearly recognised as oil and starch. Homogeneous protoplasm destitute of 

 granules is found in the cotyledons of dormant embryos of Helianthus, and in the first 

 leaves of Phaseolus ; out of it chlorophyll is subsequently formed, and it contains but 

 very little water; but the extremely watery protoplasm which rotates in the cells of 

 Vallisneria is also not itself granular; nothing but nucleus and chlorophyll-granules 

 can ba recognised in it. In the development of the spores oi Equ'isetum (Fig. 10, p. 14) 

 the finer granules separate repeatedly from the homogeneous protoplasm, and afterwards 

 become again distributed through it. But in some cases the protoplasm is so loaded 

 with granular and coloured materials, that the colourless hyaline basis can no longer be 

 distinguished ; as, for instance, in the oospheres of Fucus (Fig. 2, p. 3), the zygospores 

 of Spirogyra (Fig. 6, p. 10), and in many spores and pollen-grains \ In the reservoirs 

 for reserve-materials contained in dry seeds {e.g. the cotyledons of peas and beans), 

 the protoplasm itself is often contracted into small roundish grains, among which lie 

 the starch-grains. 



(b) Skin, Vacuoles, Mo'vement'^ . Naked protoplasm-bodies, as the plasmodia of the 



^ Hanstein gives to the substances mingled with the true protoplasm, and which undergo many 

 transformations, the collective name of Metaplasm. (Bot. Zeitg. 1868, p. 710.) 



" [The recent observations of Strasburger differ in some respects from what is stated in the 

 text. Strasburger recognises a differentiation of protoplasm into two layers, which may be termed 

 Ectoplasm and Endoplasm respectively In vegetable cells the former is hyaline, while the 

 chlorophyll-grains are imbedded in the latter. The ectoplasm does not however consist of the 

 mere hyaline basis of the protoplasm, nor is it identical with the skin which is formed on a free 

 surface when exposed, but is the result of a true process of differentiation. In numerous cases, 

 though not universally, Strasburger has found that the ectoplasm presents the radial striation 

 referred to in the text, and sometimes also a striation parallel with the surface. In the swarm-cells 

 of V.iucheria treated with a one per cent, solution of osmic acid, he found that this striation depended 

 on th:i presence in the ectoplasm of small rods of denser, imbedded in more watery protoplasm. 

 Extern illy and internally these rods are in contact with a delicate continuous layer of protoplasm, 

 and the cilia, which are more slender than the rods and about twice as long, arise from them. In 

 the earliest stage the cilia are small processess of the ectoplasm corresponding in position to the rods 



