PROTOZOA o 



Foraminifera form an order of the class Rhizopods that is of some 

 economic importance because of the limestone that is formed from the 

 dead calcareous shells or tests, Fig. 6. One of the best known of the 

 foraminifera is Globigerina. This form, which is about the size of a 

 small pin-head, is widely distributed over the ocean, and the shells of 

 the dead animals fall to the sea bottom where they form the so-called 

 Globigerina ooze, that solidifies to form gray chalk. 



Nummulites are the largest of the foraminifera, sometimes reach- 

 ing the size of a silver dollar, which they resemble somewhat in shape. 

 The pyramids of Egypt are built largely of nummulitic limestone. 



Radiolaria are an order of Rhizopods having usually a complicated 

 skeleton of silica. They are all marine forms and after death their 

 skeletons settle to the sea floor as radiolarian 

 ooze, sometimes hundreds of feet thick, that 

 forms flint or quartz. 



Mastigophora. Of the pathogenic flagel- 

 lata the best known genus is Trypanosoma, 

 of which there are several species, parasitic 



n -, e . i ~ PIG. 2. A try panosome ; 



in all classes of vertebrates up to man. One a parasitic flagellate. 

 of the most terrible diseases to which man is Greatly magnified, 

 subject is trypanosomiasis or sleeping sick- 

 ness, which of late years has been sweeping over Africa and destroying 

 the natives by the hundreds of thousands. It is said to be fatal in 

 100 per cent, of the cases, tho headway is being made toward discover- 

 ing a cure. 



The organism concerned is T. Gambiense, Fig. 2, which is introduced 

 into the human blood by the bite of the tsetse fly, Glossina palpalis. 

 Whether the protozoan undergoes a part of its life history in the body of 

 the fly or is merely carried mechanically is a debated question; possibly 

 there may be another and an unknown host; at any rate it has been 

 found that the spread of the disease may be checked by cleaning up 

 the brushy areas along streams and water-courses. 



Just how the trypanosoma produces its ill effects is uncertain; 

 it may be found in the blood, where it destroys the red cells, and in the 

 cerebrospinal fluid. The disease, which may run its course in -a few 

 months or last for years, exhibits various symptoms, the most evident 

 of which is a marked drowsiness or coma that has given the popular 

 name to the disease; the patient loses all desire for food and gradually 



