than attempting to destroy it." Man, then, would 

 be an important factor in the purification of 

 his own drinking water. Appropriate plank- 

 tonic organisms would consume objectionable 

 inorganic solutes in the water, use them in the 

 manufacture of proteins, and then be eaten by 

 man. The purified water could also be con- 

 sunned safely by man. 



Industrial Uses 



The importance of planktonic organisms to 

 mankind does not end with their death. The 

 shells of certain groups of these organisms 

 have sunk to the bottom of the sea for millions 

 of years. In some localities, these shells 

 became fossilized and were eventually raised 

 above the surface of the water by movements 

 of the earth's crust. The uses made of some 

 of these materials are essential to our modern 

 way of life. 



Diatoms- -diatomaceous earth .- -Deposits of 

 fossil diatoms, called diatomaceous earth, 

 have nnany industrial uses. The oldest use is 

 as a powder for polishing metals and cleaning 

 kitchen utensils. Because of its porosity, 

 diatomaceous earth is used as an absorbent 

 for nitroglycerine in the manufacture of dyna- 

 mite, and as a filter for liquids, especially in 

 the refining of sugar and in the manufacture 

 of rubber. Diatomaceous earth is also used 

 to insulate blast furnaces and to strengthen 

 concrete. 



Foraminifera--chalk and limestone . --An- 

 other well-known commodity that owes its 

 origin to the plankton of ancient seas is the 

 chalk so widely used by teachers and students. 

 Huge chalk deposits, formed by shells of dead 

 Foraminifera (especially Globigerina and its 

 allies), are the famous Cliffs of Dover, Eng- 

 land; Fort Hayes Chalk in Kansas; Niobrara 

 Chalk in Nebraska; and other deposits in Ala- 

 bama, Mississippi, and Tennessee. 



The shells of Foraminifera also contributed 

 much to the formation of calcareous rock or 

 limestone. Limestone has many commercial 

 uses, including the making of the most impor- 

 tant building materials of our time- -directly 

 as stone blocks and marble, and indirectly in 

 steel, cement, and plaster. It is also used in 

 building roads and for reducing the acidity of 

 soils in agriculture. 



The Foraminifera that contribute to the for- 

 mation of limestone are strange little one- 

 celled animals that secrete calcareous shells 

 around tnemselves. As they grow larger, they 

 build and move into progressively larger cham- 

 bers which usually are arranged in a spiral. 

 The name Foraminifera, from the Latin fora- 

 men (a hole) and fero (to bear), was given the 

 organism because the shells are perforated 



by a large number of small holes through 

 which are extended slender strands of proto- 

 plasm called pseudopodia. Outside the shell, 

 these protoplasmic strands branch and inter- 

 weave to form a living network which resem- 

 bles a spider's web but operates very differ- 

 ently; it is both the spider and the web. When 

 a victim is caught in this sticky web the 

 strands of the net pour out digestive juices 

 that convert the prey into a solution or emul- 

 sion which passes into the protoplasnn of the 

 foraminiferan. 



Not all Foraminifera have been tiny. The 

 Camerina . which reached its peak of abundance 

 in rather recent geologic time but is now ex- 

 tinct, attained a diameter of 7-1/2 inches. Its 

 shells formed limestone in Europe, Asia, and 

 northern Africa. 



All plankton--petroleum .-- The origin of pe- 

 troleum (rock oil) is still a mystery to au- 

 thorities in geology, chemistry, and astronomy 

 who have spent many years studying it. Two 

 opposing theories have been advanced: (1) that 

 the oil was formed from inorganic substances 

 during volcanic action and later seeped into 

 sedimentary rocks, and (2) that it was formed 

 from organic substances leached from decay- 

 ing plants and animals. The latter theory was 

 advanced first and is still held by most 

 scientists. If this is the true origin of oil, 

 then microscopic algae may have been an 

 important, if not the most important, source 

 of petroleum in sedinnents from paleozoic to 

 tertiary time. Tne shells of radiolarians, 

 foraminifers, and diatoms are present in sedi- 

 ments closely associated with oil. 



Petroleum is of prime importance in the 

 world today. A tremendous variety of impor- 

 tant products are derived from crude petro- 

 leum, many of which are essential for develop- 

 ment of the activities of modern civilization. 

 Natural gas, gasoline, diesel oil, fuel oil, and 

 lubricating oils and greases are used to heat 

 buildings in cold climates, to provide heat for 

 cooking, and to power and lubricate highspeed 

 motors that nnake possible modern rapid 

 transportation on land and sea, and in the air. 

 They also supply heat and power for the opera- 

 tion of most industries. Other important prod- 

 ucts are: asphalt to build smooth roads; 

 synthetic rubber to provide tires for automo- 

 biles that travel these roads; antifreeze prep- 

 arations to protect the cooling systems of the 

 cars in freezing weather; soaps and antisep- 

 tics for sanitation and cleanliness; paints, 

 paint driers, a turpentine substitute; auto, 

 furniture, and metal oolishes to protect sur- 

 faces and enhance beauty; inks for writing; 

 and fertilizers to improve yields of food 

 crops. In addition there are medicines, ex- 

 plosives, solvents, acids, carbon bricks, and 

 many other products too nunrierous to mention 

 here. 



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