1891.] On the Structure of Amoeboid Protoplasm, tyc. 197 



muscle contracts, the homogeneous substance passes from the 

 intervals into the pores of the sarcous element, and thus enlarges the 

 latter, while the clear intervals are proportionately shortened, so 

 that in extreme contraction they may disappear, and the swollen and 

 bulged sarcous element may almost abut against the tranverse 

 membranes. On the other hand, when the contraction passes off, and 

 the 'muscle becomes extended, the homogeneous substance passes out 

 of the pores of the sarcous element into the clear intervals ; the 

 latter become manifest, and the sarcous element proportionately 

 diminished in bulk. It is hardly possible that the resemblance of 

 these changes to those which occur in the protoplasm of an amoeboid 

 cell is merely accidental difficult not to believe that the perforated 

 sarcous substance is the spongioplasmic " cecoid," the clear labile 

 substance the hyaloplasmic " zooid." 



This conception of the structure and mode of activity of the 

 amoeboid cell and of muscle, whilst bringing them under exactly the 

 same category, and thus tending to simplify our ideas regarding con- 

 tractile phenomena, may also serve to aid in the elucidation of certain 

 uestions in connection with those phenomena which have long 

 'resented difficulties to the physiologist and pharmacologist. For 

 pie, with regard to the movements of amoeboid cells, the 

 question has been frequently discussed, and never satisfactorily 

 answered, whether we are to regard the withdrawal of the pseudo- 

 podia into the body of the cell as the condition of rest, and the 

 protrusion of the pseudopodia as the condition of activity, or vice 

 versa. Viewed by the light of the above observations, it is clear that 

 neither state is to be regarded as a resting condition ; both are mani- 

 festations of activity ; both are produced by flowing of the hyaloplasm, 

 limilarly, in the case of muscle, the passage from the contracted to 

 e extended condition can no longer, as is so frequently assumed, be 

 >ked upon as a merely passive change of state, but must be 

 rded, no less than in the case of the passage from the extended to 

 e contracted condition, as produced by flowing of hyaloplasm. In 

 .e one case this flows into pores of the spongioplasm this is the 

 ndition called contraction, and ordinarily regarded as the active 

 ,te ; in the other case there is a flowing of the hyaloplasm out 

 the pores of the spongioplasm, by which movement the condition 

 extension is determined. That different chemical and electrical 

 anges accompany, perhaps determine, these different directions of 

 movement is well known. It is also known that the process of exten- 

 ion is influenced by drugs, independently of the action they may 

 :ert upon that of contraction (Brunton, Ringer). But whether the 

 ihemical and electrical changes, and those produced by drugs, occur 

 in the hyaloplasm, or in the spongioplasm, or in both substances, is a 

 uestion which, as in the analogous case of the amoeboid cell, cannot 



