1919] Kofoid-Sivezij: Trichomjmpha campanula 49 



troblepharoplast at mitosis is suggestive of some sti'uctural relation 

 such as is represented by the nuclear rhizoplast in the Polymastigiua, 

 but no rhizoplast has as yet been found by us in TrichmiympJia. 



ECTOPLASMIC STEUCTURES 



A superficial examination of T. campanula reveals the fact that 

 the anterior two-thirds of the body is marked off by a thick ectoplasm. 

 This is thickest anteriorly and as its extreme posterior limit becomes 

 thin, disappearing distally in the frail pellicle of the posterior region 

 of the body (fig. B ; pi. 5, fig. 6). Under the low powers of the micro- 

 scope this appears as a nearly clear zone in the living flagellate, dis- 

 tinctly marked off from the granular endoplasm. Higher magnifica- 

 tions bring out the fact that it is divided into three distinct zones 

 which are traversed bj^ fine lines and that one layer or zone contains 

 alveoli closely massed together. These are, (1) the outer projecting 

 ridge, (2) the alveolar layer, and (3) the inner ectoplasmic layer 

 (fig. B; pi. 12, fig. 80). In stained material the structure of the ecto- 

 plasmic region can be more clearly differentiated, and reveals a high 

 degree of complexity. These regions will now be described, beginning 

 with the outer zone and proceeding inward. 



Surface Ridges : The outer surface of the body is raised in rela- 

 tively high, narrow, longitudinal ridges (fig. B, surf, rdg.) which are 

 best observed in a transverse section (pi. 5, fig. 4; pi. 12, fig. 80). 

 The cilia or flagella which cover the surface of the body spring from 

 the crest of each ridge. These ridges extend from the anterior end 

 posteriorly to the equator. The spaces separating them become nar- 

 rower anteriorly and the ridges fewer in number, finally converging 

 around the base of the operculum-like structure at the extreme 

 anterior tip of the body (pi. 5, fig. 1). Posteriorly they fade out 

 at the point where the differentiated ectoplasm and flagella disappear, 

 giving place to the thin periplast of that region of the body. The 

 crests, or tops, of the ridges are narrow or knifelike. The base of each 

 ridge is usually somewhat compressed (pi. 5, fig. 4). Farther 

 posteriorly the base becomes broader (pi. 12, fig. 80) and the ridges 

 disappear so that the entire surface becomes smooth. The ridges have 

 been well illustrated by Porter (1897, p. 2, fig. 17) for T. agilis, cross- 

 sections of the body being nearly identical in that species and T. 

 campanula. Their course is longitudinal, not spiral, and is not 

 changed to a spiral on contraction. 



