PROTOZOA AS CELLS 15 



elaborating protein secretions for export, the granular reticulum 

 takes the form of impressive arrays of concentric double lamellae 

 forming flat sacs or cisternae. Such arrays may be called ergasto- 

 plasm (thus the terms ergastoplasm and endoplasmic reticulum 

 overlap broadly; for a history of the concepts and terminology 

 see Hagenau, 1958; and Porter, 1961). Ergastoplasm is extensively 

 developed, for example, in pancreatic acinar cells (Palade, 1959) 

 and in lactating mammary epithelium (Wellings, DeOme, and 

 Pitelka, 1960); it has also been found in several kinds of inverte- 

 brate cells {e.g. the developing cnidoblasts of Hydra, Slautterback 

 and Fawcett, 1959), but where it occurs in protozoa it usually is 

 limited to scattered sacs or a few parallel cisternae, and a relation- 

 ship to protein synthesis has not been demonstrated. 



The Golgi Apparatus 



Electron-microscope studies have put an end to a long- 

 continuing controversy over the reality of the Golgi apparatus by 

 proving that it is a well-defined membranous entity present in 

 most if not all eucells. It consists (Fig. 3, PI. I) of small to large 

 piles of thin, flat sacs, never bearing Palade particles — but 

 occasionally in continuity with granular cytoplasmic membranes. 

 Minute vesicles clustered at the edges of the sacs appear to be 

 pinched off from their rims. Larger vacuoles represent inflated 

 single sacs. The dictyosomes of animal spermatocytes, the 

 dictyosomes and true parabasal bodies of flagellates (but not all 

 structures that have been called parabasals), and the Golgi zones 

 of metazoa all fit this description, and similar structures occur in 

 plant cells and in many protozoa not previously supposed to 

 contain them. 



Grasse and his colleagues must be credited for much of the 

 work of bringing the identification of Golgi elements in protozoa 

 into line with the picture seen in- metazoan cells. Following 

 earlier light-microscope studies (reviewed by Grasse and Hollande, 

 1941), they sought and found Golgi structures in electron micro- 

 graphs of gregarines (Theodorides, 1959), and of ciliates (Noirot- 

 Timothee, 1957) as well as of a variety of flagellates (Grasse, 1956a, 

 1957a, 1957b, 1957c; Grasse and Carasso, 1957). Grasse (1957c) 

 further has characterized the Golgi apparatus as a distinctly 



