114 



PROTOZOOLOGY 



droplets occur in various Protozoa and when there is a large number 

 of oil-producing forms in a body of water, the water may develop 

 various odors as indicated in Table 4. 



Table 4. — Protozoa and odors of water 



Fats occur widely in Protozoa. They appear usually as small re- 

 fractile globules. Zingher (1934) found that in the Sarcodina and 

 Ciliata he studied, each species showed morphological characteristics 

 of the fatty substance it contained. Fat globules occur abundantly 

 in Amoeba and Pelomyxa which are easily seen by staining with 

 Sudan III. In Tillina canalifera, fat droplets, 1-2/x in diameter, are 

 present especially in the region to the right of the cytopharynx 

 (Turner, 1940). According to Panzer (1913), the fat content of 

 Eimeria gadi was 3.55 per cent and Pratje (1921) reports that 12 per 

 cent of the dry matter of Noctiluca scintillans appeared to be the 

 fatty substance present in the form of granules and is said to give 

 luminescence upon mechanical or chemical stimulation. But the 

 chemical nature of these "photogenic" granules is still unknown at 

 present (Harvey, 1952). A number of other dinoflagellates, such as 

 Peridinium, Ceratium, Gonyaulax, Gymnodinium, etc., also emit 

 luminescence. In other forms the fat may be hydrostatic in function, 

 as is the case with a number of pelagic Radiolaria, many of which 

 are also luminous. Luminescence in Protozoa (Harvey, 1952). 



Another reserve food-stuff which occurs widely in Protozoa, ex- 

 cepting Ciliophora, is the so-called volutin or metachromatic gran- 

 ule. It is apparently equally widely present in Protophyta. In fact 

 it was first discovered in the protophytan Spirillum volutans. Meyer 



