196 Prof. E. A. Schafer. fFeb. 



plasm, not by the contraction of the spongioplasm (as conceived 

 Carnoy*), that the movements of cells are produced.f Of the t 

 substances, the hyaloplasm is the more active, the spongioplasm 

 more inert. The spongioplasm forms, in fact, a sort of framewi 

 supporting the hyaloplasm, and into which under the influence 

 stimuli the hyaloplasm becomes wholly withdrawn. To adopt 

 Brnecke's well-known terminology, the hyaloplasm is the zooid, the 

 spongioplasm its oscoid. 



Whether one or other of these two substances is ever wholly 

 absent from the protoplasm of cells is a question which cannot at 

 present be decided. There are cells and unicellular organisms, both 

 animal and vegetable, in which no reticular structure can be made 

 out, and these may be formed of hyaloplasm alone. In that case, 

 this must be looked upon as the essential part of protoplasm. So far 

 as amoeboid phenomena are concerned, it is certainly so ; but whether 

 the chemical changes which occur in many cells are effected by this 

 or by spongioplasm is another question. Certainly, the reticulnm is 

 always very well marked in cells in which considerable chemical 

 changes are produced, e.g., gland cells. 



The movements within plant cells must also be regarded as due 

 the flowing of hyaloplasm. It is, indeed, impossible to conceive t 

 the contraction of a reticulum could produce the circulation of 

 protoplasm which is seen within a cell of Valltsneria. How t 

 flowing is produced is an entirely different question, and one w 

 must at present remain unanswered. 



If now we compare the structure of protoplasm with that 

 striated muscle, we find many points of coincidence. As is we 

 known, the muscle columns of the wing muscles of insects ("wing- 

 fibrils " of authors) are divided by transverse partitions (membranes 

 of Krause) into a series of segments (sarcomeres, Aluskel-kastchen. 

 of Krause), each of which contains a sarcous element or disk of 

 anisotropous sarcous substance (which is really formed of two halves, 

 their junction being often visible as the line of Hensen), and a homo- 

 geneous isotropous substance, which in the extended muscle occupies 

 the intervals between the sarcous element and the transverse mem- 

 brane. As I have elsewhere recently shown,J the substance of the 

 sarcous element is penetrated by pores or canals which extend in each 

 half of the element as far as the line or plane of Hensen, and which 

 are occupied by clear substance continuous with the homogeneous sub- 

 stance of the intervals. The substance of the sarcous element stains 

 with heematoxylin and similar reagents, while the homogeneous 

 substance of the clear intervals remains unstained. When the 



* ' Biologie Cellulaire,' 1886. 



t Of. Leydig, ' Zelle u. Gewebe,' Bonn, 1885. 



J ' Monthly International Journal of Anatomy and Physiology,' voL 8, 1891. 



