PLIOCENE PERIOD 



4708 



PLOW 



was born at Novum Comum. He lost his 

 father when but nine years old, and two years 

 later he was adopted by his uncle (see above). 

 The educational advantages given him were 

 excellent, and he made such good use of them 

 that before his twentieth year he was known 

 as one of the most learned men of the time. 

 He studied under Quintilian, was a popular ora- 

 tor, and held a number of offices, serving in sue- 

 on as military tribune, quaestor, praetor 

 and consul. The last known date in his life 

 is 103, the year in which he was made proprae- 

 tor of Bithynia; when he died is not known, 

 though it is probable that he lived at least ten 

 years after that time. Besides his eulogy of the 

 Emperor Trajan, nothing of his writings re- 

 mains except the letters, which give interesting 

 pictures of the life of the times. B.M.W. 



Consult Simcox's A History of Latin Literature. 



PLIOCENE, pli'oseen, PERIOD, the divi- 

 sion of the Cenozoic Era extending from the 

 Miocene to the Glacial Period. The rock sys- 

 tems of the period are more important in 

 Europe than in America. Extensive erosions, 

 which brought material from the mountains 

 and deposited it on the plains, were a strong 

 feature of the period (see EROSION). Along the 

 Atlantic and Gulf coasts an extensive deposit 

 of gravel was formed. Only small areas of 

 Pliocene rock appear in other parts of the 

 United States and none in Canada. During the 

 period plants and animals seem to have re- 

 moved to those regions in which the climate was 

 adapted to them, and there was an interchange 

 of plants and animals between North and South 

 America. The llama, the camel, the horse, the 

 rhinoceros and the tiger lived in North America. 

 In Europe were found animals similar to those 

 now found in Africa. 



Related Subjects. The reader is referred to 

 the following articles In these volumes : 

 Cenozoic Era Glacial Period 



Geology, diagram, page Miocene Period 



2439 



PLOVER, pluv'er, a very large family of 

 birds found in almost every part of the world. 

 Many of them are tide birds, living in marshy 

 places and on coasts where they pick up the 

 small bits of food washed in by the tide. Spe- 

 cies common in North America are the black- 

 bellied plover, a bird having black breast, legs, 

 head and bill and spotted black and white 

 back; the golden plover, much like the black- 

 bellied, but having golden-yellow spots on its 

 back; the ring plover, having a circle of white 

 around the throat. These three plovers and a 



THE RING PLOVER 



few others live inland through the summer 

 months and during that time are much-prized 

 game birds. Their bodies, about 12 inches long, 

 are rounded and their wings long and strong, 

 adapted to long-distance flights. 



The golden 

 plover, which of 

 all the family has 

 the greatest 

 range, breeds in 

 the Arctic regions 

 and in winter mi- 

 grates as far 

 south as Patago- 

 nia, in South 

 America. The 

 female, after laying four creamy-white, choco- 

 late-marked eggs in her very crude nest, flies 

 away and allows the father to hatch the eggs. 

 These plovers feed on insects and worms, and 

 are especially fond of grasshoppers. 



The black-bellied plovers are very distrustful 

 of people and are constantly finding cause to 

 excite a whole neighborhood of birds with their 

 warning cries. Their nests are mere hollows in 

 the ground, sometimes quite bare, sometimes 

 lined with a bit of dry grass. When the nest 

 is approached the mother bird flies off and 

 limps along the ground, dragging a wing in or- 

 der to attract attention to herself and away 

 from her eggs. All of the plovers have similar 

 plaintive notes. They have a curious habit, 

 when startled, of running quickly a short dis- 

 tance, then stopping with a jerk to look about 

 in all directions as if to locate the source of 

 danger. 



PLOW. When man first began to plant seeds 

 he used a stick with which to dig up the ground. 

 Later he tamed the ox and the ass, and seeing 

 that more soil could be turned up by hitching 

 one of these animals to a forked stick, he took 

 the fork of a tree, sharpened one prong, at- 

 tached the animal to the other and used the 

 main branch for a handle. This was the first 

 plow, and the plow used by the peons in Mexico 

 to-day is but little better. 



It is a far cry from the forked stick to the 

 modern plow, but the degree of perfection in 

 the plows of to-day has been reached only 

 through centuries of study and invention. In 

 this progress America has in the last two cen- 

 turies taken the lead, and there are now made 

 more than a thousand patterns of plows, each 

 adapted to the special needs of the locality in 

 which it is to be used, or to the preparation of 

 the soil for a special crop. The v'-~ o o c Q 



