1913] Kofoid-Swezy: 8trehlo>iinsti.c strix 7 



Cytoplasm 



The cell contents are nudifferentiated. No separation of ectoplasm, 

 pellicle, and endoplasm is visible. There is no cytostome and no food 

 particles or food vaenoles have been detected. There is no contractile 

 vacuole visible. The only differentiated structures normally visible 

 in the organism are the nucleus and the neuromotor apparatus. 

 However, on treatment with neutral red (fig. A) certain gramdes 

 became stained in the axial c.ytoplasm in the posterior two-thirds of 

 the body, indicating an endoplasmic territory within which diges- 

 tion of the absorbed food was in progress. 



Neuromotor Appar.vtus 



This neuromotor apparatus consists of a centrosome, rhizoplast, 

 blepharoplast, myonemes, and six tlagella. The centrosome (fig. A, 

 cent.; pi. 1, fig. 9; pi. 2, fig. 10) is found at the anterior tip of the 

 elongated nucleus. It appears to be a spherical granule in or on the 

 nuclear membrane. It is temporary or evanescent and does not appear 

 to play any visible' part in either binary or multiple fission. It is 

 quite possible that the granule thus interpreted is a mere temporary 

 accumulation of chromatoidal substance on the rhizoplast without 

 morphological meaning. Its position with reference to nucleus, rhizo- 

 plast and blepharoplast is similar to that of the centrosomes in Giardia 

 (Kofoid and Christiansen, 1915, and Boeek, 1917) hence the designa- 

 tion suggested. It may be that the extrusion of the rhizoplast serves 

 to bring the structure into view from a more intimate union with 

 the nuclear membrane. 



The rhizoplast (fig. A, rh.) is a slender, deeply staining thread 

 running anteriorly from the centrosome or the anterior tip of the 

 nucleus to the blepharoplast. Its length ordinarily is about equal 

 to the greatest diameter of the body and the line of demarcation 

 between the attenuate end of the nucleus and this thread is often 

 not readily determined. There is a probability that this is more or 

 less contractile, as is seen on a comparison of our figures. In one 

 instance (pi. 1, fig. 7) this structure appears to be foreshortened 

 and thickened, by contraction, onto the anterior end of the nucleus. 



One remarkable feature of this structure is its capacity of being 

 extended beyond the anterior end of the body as a long spike bear- 

 ing the blepharoplast and its attached flagella at its tip. A con- 



