130 SYNDEY H. VINES. 



a granular appearance. They are, in fact, formed from the 

 homogeneous matrix of the endoplasm. 



The endoplasm of many Rhizopoda shows a more com- 

 plete differentiation than any which may be seen in vegetable 

 cells. Tn the Heliozoa, for instance, the substance of 

 which Professor Strasburger believes to consist of endoplasm 

 only, the distinction of a cortical from a medullary portion, 

 ectosarc from endosarc, is discernible. The nucleus always 

 lies in the endosarc, whereas the ectosarc contains the con- 

 tractile vesicle. 



In Actinosphoerium, for instance, the endosarc is distin- 

 guished from the ectosarc in consequence of its coarser 

 granulation. On the other hand, in the Heliozoa Skeleto- 

 phora, the ectosarc is much more granular than the endosarc, 

 and it subserves the functions of prehension and digestion 

 of food, which, in ActinosphcBrium are discharged by the 

 endosarc. 



By his observations Professor Strasburger is led to form 

 some general conclusions with reference to protoplasm. 



In the first place, he feels himself to be in a jDOsition to apply 

 to protoplasm the hypothesis of the molecular constitution 

 of organised bodies which was formulated by Naegeli.^ In 

 his ' Experimental Physiologic,'^ Sachs suggests that proto- 

 plasm, like other organised structures, may possibly consist 

 of minute solid particles invested by watery areas, and with 

 this view Professor Strasburger entirely concurs. He at- 

 tributes the definite form and the well-marked vital pheno- 

 mena of protoplasm to the activity of its molecules, and he 

 refers all those properties which it possesses in common 

 with fluids to the water by which its molecules are invested. 

 The more watery the protoplasm the more evident are its 

 fluid properties, as is shown by the ease with which masses 

 of such protoplasm will coalesce, the rapid protrusion and 

 retraction of processes, &c. The denser the protoplasm, the 

 more exclusively does it exhibit the properties of its mo- 

 lecules. At this point, however, the application of Naegeli's 

 hypothesis to protoplasm must cease. With reference to other 

 organised structures (cell- walls, starch-granules, «&;c.),Naegeli 

 goes on to show, by evidence drawn from their optical pro- 

 perties, that their molecules possess definite crystalline forms, 

 but there is no ground whatever for believing that the 

 molecules of protoplasm resemble the molecules of other 

 organised structures in this respect. 



In the second place he points out that protoplasm is to be 



' ' Naegeli u. Schwendener des Mikroskop.,' p. 417, ff. 1867. 

 2 French edition, p. 4G9. 



