52 BIOLOGY OF THE PROTOZOA 



a hydrostatic function in the activities of different organisms. 

 Globules of smaller size but conspicuous by their frequently brilliant 

 coloring are found in many types of flagellates and ciliates. In some 

 cases, notably in NociUuca miliar is and in several Dinoflagellates, 

 these metaplasmic oils are photogenic and, in contact with oxygen, 

 produce phosphorescence often of great brilliancy (de Quatrefages, 

 1850, E. B. Harvey, 1917). Similar globules of oil stored up in 

 flagellated Protozoa, minute as they are in the individual, may 

 become a great nuisance collectively. Potable waters, for example, 

 are frequently rendered unpalatable because of the odors and tastes 

 due to these products of metabolic activity. Such objectionable 

 odors and tastes are rarely due to the putrefaction of the organisms, 

 but rather to the liberation of minute drops of oil upon disintegra- 

 tion of the cell bodies. As crushing a geranium leaf causes minute 

 drops of oil to be thrown in the air, giving the fragrant perfume of 

 that plant, so disintegration of cells of Uroglenopsis americana, 

 crushed by the pressure in pumps and mains, causes the liberation 

 of minute oil drops stored in the protoplasm, but the cod-liver oil 

 smell which they impart to the water is far from fragrant. So 

 characteristic are these metaplasmic products of the organisms 

 which produce them that many kinds of flagellates which accumu- 

 late in drinking waters may be recognized simply by the odors 

 which they impart (Calkins, 1891). 



Cellulose and pseudo-chitin are products of cellular activity which 

 are useful in the formation of membranes, shells and tests. Cellu- 

 lose, as in higher plant cells, forms the lifeless membrane of many 

 chlorophyll-bearing types, while protein derivatives in the form 

 of chitin and pseudo-chitin are more widely distributed through the 

 entire group of Protozoa, forming the substratum upon which, or 

 between layers of which, shell materials are deposited, while cups, 

 tests or "houses," cyst membranes, stalks etc., are formed directly 

 from its substance. Shell and skeleton materials such as calcium 

 carbonate, silica, strontium sulphate, etc., are likewise formed as 

 results of metabolic activity, sometimes continuously, as in the lime- 

 stone shells of the Foraminifera, and sometimes periodically at 

 intervals of saturation (dictyotic or lorication moment) as in the 

 formation of the characteristic silicious skeletons of the Radiolaria. 



Pigments of various hues are also frequently found in Protozoa. 

 In some cases, as in Actinosj^hcBrium eichhornii, they are formed as 

 a final product of degeneration of chromatin granules (chromidia) ; 

 in other cases they are products of metabolic activities following 

 the digestion of specific kinds of food, as melanin pigment, brown or 

 black in color, which follows the digestion of haemoglobin by malaria- 

 causing hemosporidia {Plasmodium species). Specific coloring 

 matters are found here and there, especially amongst the ciliates 

 which have nothing to do with chlorophyll and which are named 



