96 General Biology 



reaction. They may be killed by light or heat. Their activities are 

 specific, each type of enzyme doing only one particular type of work. 

 Every step in the breaking down of proteids is done by a specific 

 enzyme. 



Inorganic. 



A. Always present, and called essential constituents. 



C, O, H, N, Ca, Na, K, Cs, Fe, Mg, H,0, NH 4 , CO,, SO + , PCX. 



B. Sometimes present. 



I, Br, NO,, NO.,, Zn, Ba, Cu, Mn, As, F, Si, Al. 

 Muttkowski has summarized the chemical constituents concerned in living 

 matter as follows: 



I. Constituents concerned with food. 



1. Those which compose food. 



A. Proteins—C, O, H, N, (S, P)— build protoplasm. 



B. Fats — C, H, O — energy and reserve. Certain P-fats enter into 

 building up of all protoplasm (lecithin). 



C. Carbohydrates — C, O, H — furnish the energy and reserve in pro- 

 toplasm. 



2. Constituents concerned in food synthesis. 

 Mg, CO, (in plants only). 



3. Concerned with food storage — K. 



4. Katalysts — Fe, Ca, Mn, I. 



II. Constituents concerned with Physiological Processes. 



1. Regulation (turgor, toxicity) — K, CI, Na, Ca, I, Br. 



2. Sensory — P. 



III. Constituents concerned with Structural Relations. 



1. Form relations — elasticity — N, CI. 



2. Supporting tissues — C, Ca, Si, Mg, P, Fl, (S) in form of phosphates, 

 carbonates, oxalates. 



CELL DIVISION 



Every living thing, plant or animal, begins its life as a single cell. 

 Therefore, it follows that, if one wishes to understand how a many-celled 

 animal (metazoan) ( ) comes to its adult form of 



life, one must find an original single cell and follow it throughout all its 

 changes until it has come to adultship. 



Every living cell grows if it obtains food, and, when it reaches its 

 maximum size, splits in two. It may do this equally or unequally; that 

 is, it may split into a very large and a very small part, or it may split 

 equally into halves of like size and shape. There are then two cells 

 where there was only one before. These two cells then grow until such 

 time as they attain their maximum size when the same process is gone 

 through again, so that in a short time there are four cells, then eight, 

 sixteen, thirty-two, sixty-four, one hundred twenty-eight, and so on. 



It is easy to understand what a division of cells may bring about 

 when an old children's story is recalled. According to this story, a 

 blacksmith expressed his willingness to shoe the King's horse on Sunday 

 provided the King would pay one cent for the first nail, and double that 

 amount for each additional nail. By the time the blacksmith had driven 

 in the twenty-eighth nail, he had won more than a million dollars for 

 the last nail alone. In the case of the tiny bacteria, which are single- 



