HiEMATOCOCCUS (SPHAERELLA) 



187 



which forms the inner part of the thick wall. This mucilage is 

 traversed by a number of, usually branched, thread-like pro- 

 longations of the protoplast extending up to the surface layer 

 (Fig. 98, A, C), and comparable to the cytoplasmic strands in the 

 pit-canals of higher plants. Practically the whole of the 



Fig gS. — Hcsmatococcus (Sphaerella). A and C, Hcemalococctts phivialis, 

 motile individuals (after Schmidlc). B, D, and E, H. droehakensis 

 (after Wollenwcbcr). B, Resting cell ; D, single individual in optical 

 section, showing the chloroplast (f.) ; It, the same, in surface view, 

 showing the numerous contractile vacuoles ; F, an individual of 

 Carteria (after Takeda). «., nucleus ; p., pyrenoid ; S., ej'e-spot. 



peripheral region of the cytoplasm is occupied by an ill-defined 

 reticulate chloroplast (Fig. 98, D, c), containing a number (2-8) 

 of scatteredjpyrenoids (p.), and bearing an eye-spot (S.) near the 

 front end. The contractile vacuoles (Fig. 98, E) are numerous 

 and irregularly distributed. 



