1920] Taylor: Neuromotor Apparatus in Euplotes 419 



Endoplasm 



In his microdissection studies on living ova of certain marine 

 invertebrates. Chambers (1917a) finds their cytoplasm to consist of 

 "a hyaline fluid matrix in which are imbedded granules of various 

 sizes." The granules, classified into microsomes and macrosomes, 

 differ considerably not only in size but also in number, shape, solu- 

 bility, refractive indices and in chemical reactions. Rapid tearing of 

 the internal cytoplasm with the needle induced in that region the dis- 

 solution of the macrosomes and liquefaction of the cytoplasm in which 

 the microsomes exhibited distinct Brownian movements. Such injuries 

 sometimes spread throughout the entire cell. Also, a rapid dissolution 

 of the macrosomes occurred with the outflow of the cytoplasm into the 

 sea-water "if no protective membrane intervened." The microsomes 

 were much more resistant and displayed the dancing Brownian move- 

 ment for a considerable time after the complete disappearance of the 

 liquefied cytoplasm. A protective membrane frequently formed around 

 a mechanically injured, disorganized area within the cell or on the 

 surface of endoplasm exuding through a rupture of the surface-film 

 or ectoplasm. This membrane is directly comparable with the ecto- 

 plasm. Both represent a colloidal gel enclosing the endoplasm which 

 usually exists in the sol state but may come to form temporary organs 

 such as the cell asters (Chambers. 19176) by a reversal of the sol to 

 the gel state. 



A similar consistency of cytoplasm can be identified in Euplotes 

 patella. Here, however, the general appearance of the endoplasm is 

 considerably modified by food vacuoles which are of various sizes and 

 sometimes numerous. But with high magnification and well-regulated 

 light, hosts of small granules, comparable with Chamber's microsomes, 

 appear throughout the entire body. Larger granules or macrosomes are 

 less conspicuous and have been observed only in the endoplasm. Both 

 the large and small granules are larger than the macrosomes and micro- 

 somes described by Chambers. The small granules are fairly constant 

 in size, with a diameter of about one micron or more. Here and there 

 within the endoplasm they exhibit Brownian movement. They appear 

 round and are highly refractive. The large granules vary from three 

 to five microns in diameter, are usually opaque and often irregular in 

 shape. They have not been identified in the ectoplasm and never 

 appear within the cyclosis currents of the endoplasm. Mechanical 



