Structural Differentiation of Cytoplasm 103 



in elevation it sometimes splits into two), may belong to the cyto- 

 plasm. All these films show many points of resemblance, among 

 which is their relationship to the kinoplasm. 



KINOPLASM 

 This is a structure of more variable occurrence than those al- 

 ready described, but it seems worthy of mention in a discussion of 

 the fundamental differentiations of cytoplasm because of its pos- 

 sible physiological importance and also because of its apparent 

 relation to the various surface films. Typically the differentiation 

 to which Strasburger gave the name kinoplasm appears as more or 

 less mobile filaments or tubules of very slightly higher refractive 

 index than the matrix in which they are imbedded. To be seen at 

 all, they must be in sharp focus, which may be the reason why they 

 have been observed mainly in plant cells in which the thinness of 

 the cytoplasm keeps them almost in one plane. The chains of 

 granules carried along by the kinoplasm are, however, easily 

 observed. 



From the point of view of structure, the visibile connection be- 

 tween some of the kinoplasmic strands and the various surface 

 films is of interest. Strands can be seen to flow out of and into the 

 envelope of chloroplasts and of the nucleus. Sometimes they swell 

 to enclose small vacuoles. Streams of kinoplasm have been ob- 

 served to converge upon an applied oil drop at the moment of con- 

 tact. This points to a connection between the outer surface film 

 and the strands and also explains how granules and plastids im- 

 bedded in the cytoplasm but attached to the kinoplasm come to be 

 carried over the oil drop. It is not possible from a surface view of 

 the cytoplasm to observe at what level the strands lie. In a profile 

 view of the thicker portions of the cytoplasm of some cells, the 

 serial procession of granules which marks the position of a kino- 

 plasmic stream can be located. It ranges from the outer to the 

 inner boundary, and furthermore, streams may arch beyond the 

 general level of the cytoplasm into the central vacuole. 



The shapes and movements of kinoplasm recall the typical myelin 

 processes which often adorn the inner surface of the tonoplast and 

 which have also been observed in a number of cases on the outer 

 surface of the ectoplast. It is not suggested that they are identical, 

 since myelin processes proper are random structures and often 

 (though not always) the result of an abnormal environment, whereas 



