PROTOPLASM AND NUCLEUS. 45 



or mass of protoplasm which is connected with the parietal protoplasm-sac by the 

 lamellae lying between the vacuoles or by the threads. The nucleus apparently follows 

 passively the movements of the protoplasm in which it is enveloped ; it also undergoes 

 changes of form under the pressure and traction of the moving mass beneath the 

 eye of the observer. 'During the movement/ says Hanstein (A c. p. 226), 'the 

 bands of protoplasm are very tightly stretched, so that the envelope of the nucleus is 

 drawn out into sharp angles. It looks as if the nucleus (with its envelope) were 

 towed about like a ferry-boat by ropes. But since during this towing the bands 

 alter their direction and form, it is evident that the envelope of the nucleus must 

 also change its form. But not only the envelope, but also the nucleus itself, does 

 this; this latter is never spherical or of any regular form during its movement, but is 

 irregularly elongated, and usually in the direction of its motion at the time.' This 

 change in the form of the nucleus may also be recognised from the displacement of 

 the nucleoli within its mass. 



Sect. 6. The Chlorophyll-bodies and similar Protoplasmic Structures \ 



-Chlorophyll, the green colouring matter so generally distributed through the 



jgetable kingdom, is always united to definite portions of the protoplasm-mass 



►f the cells in which it is found ; these green- coloured portions of protoplasm 



lay, in contradistinction to the colouring matter itself by which they are tinged, be 



designated Chlorophyll-bodies. Every chlorophyll-body consists then of at least 



vo substances, the colouring matter and its protoplasmic vehicle ; if the former 



removed by alcohol, ether, chloroform, benzin, or essential or fatty oils, the latter 



Remains behind colourless. The colouring matter contained in each chlorophyll- 



)ody is itself only extremely small in quantity; after its removal the protoplasmic 



)asis retains not only its form but also its previous volume. The latter is always a 



Continuous soft substance containing extremely small vacuoles, in which the colouring 



latter is generally distributed universally, though not always uniformly. 



Chlorophyll-bodies arise in the young cells by the separation of the pro- 

 toplasm into portions which remain colourless and others which become green and 

 sharply defined. This may be due to very small particles of a somewhat different 

 lature either originally existing or being produced in the previously homogeneous 

 )rotoplasm, and which collect to form distinct masses. The chlorophyll-bodies 

 ,'hich arise in this manner always remain imbedded in the colourless protoplasm 

 In a similar manner to the nucleus ; they are never in immediate contact with 

 the cell-sap. Their chemical and physical properties distinctly show that their 

 iclourless basis is a substance altogether similar to protoplasm. The chlorophyll- 

 )dies consequently always behave as integral parts of the protoplasm ; and this 

 especially evident in the division of cells, conjugation, the formation of swarm- 

 Jells, &c. But the chlorophyll-bodies, when once formed, grow; and if they 

 )ossess roundish forms they may increase by division. Both processes appear always 

 to depend on the growth of the protoplasm-mass in which they are imbedded. 



' H. von Mohl, Bot. Zeitg. nos. 6 and 7, 1855; [Ann. des Sci. Nat. vol. VI, 1856, p. 139.] 



-A. Gris, Ann. des Sci. Nat. 4th Ser. vol. VII. 1857, p. 179.— Sachs, Flora, 1862, p. 129; 



[1863, p. 193. Sachs, Handbuch der Exper. Physiol, der Pflanzen, § 87, Leipzig 1865. — Hofmeister, 



^ie Lehre von der Pflanzenzelle, § 41, Leipzig 1867. — Kraus, Jahrb. fiir wissensch. Bot. VIII. 



fl87i, p. 131. [Ditto, Zur Kenntniss der Chlorophyllfarbstoffe u. ihrer Verwaudten. Stuttgart 1872. 



-For Sorby's researches on chlorophyll see Book II. chap. 3. sect. 8.] 



