PHYSICS 



Kvc-lobcd. The small green flowers 

 form small, loose clusters. The fruit 

 is a black, fleshy berry, containing 

 three seeds, which contain a good 

 deal of oil, and have the flavour of 

 almonds. The expressed oil is used 

 for burning in lamps, and for medi- 

 cine as a purgative. 



Physics. Branch of science 

 concerned with the fundamental 

 laws of the material universe. It 

 deals with the general properties of 

 matter and the manifestations of 

 various forms of energy. It may 

 broadly be divided into two heads, 

 laboratory physics and mathe- 

 matical physics. Under the former, 

 research work is carried on to ob- 

 tain the necessary data which en- 

 able the postulates and axioms of 

 mathematical physics to be stated. 



Mathematical physics, a branch 

 of science which has become of 

 great importance in recent years, 

 is concerned with obtaining axioms 

 and postulates which will enable 

 rigid mathematical rules to be 

 formulated to satisfy observed 

 phenomena. The theories of 

 matter, energy, etc., all come 

 within the domain of mathe- 

 matical physics. 



In 1920 an institute of physics 

 was formed in Great Britain under 

 the auspices of the Faraday So- 

 ciety, the Optical Society, and the 

 Physical Society of London. The 

 first president was Sir Richard 

 Glazebrook, F.R.S. See Energy ; 

 Matter ; Relativity, etc. 



Physiocrats (Gr. physis, na- 

 ture ; kratein, to rule). Nam; 

 given to an 18th century school of 

 French economists. Founded by 

 Fra^ois Quesnay (q-v.), they 

 taught that the land is the source 

 of all wealth, and agriculture and 

 mining the only industries that 

 produce wealth. They were 

 strongly opposed to the mercantile 

 system then dominant in France 

 and to a lesser extent in England, 

 and one product of their teaching 

 was the demand that all taxation 

 should be paid from the produce of 

 the land. Their doctrines had been 

 put forward earlier by Richard 

 Cantillon, but Quesnay and his 

 friends, calling themselves the 

 Economists, were responsible for 

 their extension. Dupont de Ne- 

 mours, one of the school, was re- 

 sponsible for the name. See Poli- 

 tical Economy ; Smith, Adam ; 

 consult also The Physiocrats, H. 

 Higgs, 1897. 



Physiognomy (Gr. p hys is, na- 

 ture). Art of judging character 

 from external features, especially 

 the face. Aristotle wrote about it, 

 finding a certain resemblance be- 

 tween men and the qualities of the 

 animals that in feature they re- 

 sembled. Many other writers, both 



6 \32 



in classical times and later, dealt 

 with the subject, and it was a 

 popular subject for theories of all 

 kinds. Professors of physiognomy 

 sprang up. many of them charla- 

 tans, and in 1743, in England, an 

 Act was passed providing that all 

 those pretending to be skilled 

 therein should be punished. In the 

 19th century the development of 

 the theory of evolution and scien- 

 tific studies generally took the 

 place of the older physiognomy. 

 There is, however, a modern and 

 scientific form of physiognomy, 

 which may be described" as a study 

 of the emotions as expressed by the 

 muscles. This is useful in crimin- 

 ology. See Criminology ; Phren- 

 ology ; Psychology. 



PHYSIOLOGY 



Physiography (Gr. physis, na- 

 ture; graphein, to describe). Sci- 

 ence which deals with the earth and 

 its place in nature. As a compre- 

 hensive study it is chiefly con- 

 cerned with the co-ordination of the 

 results of other sciences ; from 

 astronomy it accepts the story of 

 the earth as a planet, from geology 

 the account of the structure o fthe 

 rocks ; from meteorology and ocean- 

 ography the sum of our knowledge of 

 the air and the sea. With these fun- 

 damentals it co-ordinates the facts 

 of physical geography, and includes 

 some account of human activities, 

 thus leading to the more compre- 

 hensive study of man in relation 

 to his environment. See College 

 Physiography, R. S. Tarr, 1914. 



PHYSIOLOGY AND ITS PROBLEMS 



F. A. Bainbridge, M.D., F.R.S., Prof, of Physiology, TTniv. of London 



Articles on related subjects include Biology ; Botany ; Cell ; Life. 



See those on the various parts of the body, e.g. Brain ; Ear ; 



Heart ; also A natomy ; Medicine ; Protoplasm ; Surgery 



Physiology forms one branch of 

 biology, and deals with the func- 

 tions, as distinct from the struc- 

 ture, of living organisms, whether 

 plants or animals. The physiology 

 of plants is usually included in the 

 science of botany, and the phy- 

 siologist is primarily concerned 

 with the functions of animals. The 

 term function is used to mean the 

 characteristic actions performed by 

 an animal or by its constituent 

 parts ; thus the ear is concerned 

 with the function of hearing. 



The study of even the simplest 

 forms of animal life throws light 

 on the functions of those higher in 

 the scale of evolution, since certain 

 characteristic functions are dis- 

 played by all animals. In the first 

 place they possess the power to 

 take in food, to build this up into 

 their own substance, and to reject 

 the waste products formed during 

 this process. The power to grow in 

 size represents one aspect of this 

 function. In the second place, they 

 are able to reproduce themselves, 

 thereby giving rise to other ani- 

 mals. Finally, they are influenced 

 by changes in their surroundings, 

 these changes acting as stimuli to 

 which they can respond by some 

 alteration within themselves. It is 

 by their ability to carry out these 

 functions that living animals are 

 distinguished from inert matter, 

 and the boy who prods a frog to 

 make it jump is performing a 

 fundamental physiological experi- 

 ment, since he is trying to ascertain 

 whether the frog is alive or dead 



The simplest form of animal life 

 consists of a single cell. This is a 

 tiny particle of living material, 

 semi-fluid in consistency, and 

 called protoplasm. Part of this 



little mass of protoplasm differs 

 from the remainder in appearance 

 and chemical nature, and is known 

 as the nucleus. Chemical analysis of 

 such an organism reveals nothing 

 in its composition which may not 

 occur in dead matter, and it is not 

 by its composition or even its 

 structure, but by its power to 

 move, nourish, and to reproduce 

 itself, that we recognize an animal 

 to be alive. 



The problems which confront 

 the physiologist are : How does a 

 living animal carry out its func- 

 tions ? What processes take place 

 within it, for example, when it 

 moves in response to some stimu- 

 lus ? What conditions are neces- 

 sary to enable the animal to carry 

 out its functions in a normal man- 

 ner ? As soon as he attacks these 

 problems the physiologist finds 

 that living organisms possess two 

 characteristic properties, upon the 

 possession of which depends their 

 ability to carry out their functions. 

 The first is that the living animal is 

 constantly undergoing change, and 

 every day part of its protoplasm is 

 destroyed and is replaced by the 

 building up of new protoplasm. 

 Thus the living substance of the 

 body changes from day to day, al- 

 though this result is effected im- 

 perceptibly, and the outward form 

 of the animal does not visibly alter. 

 The second is that the animal has 

 the power to store up energy in its 

 body, and to expend part of this 

 energy from time to time ; for 

 instance, every movement on the 

 part of an animal involves the 

 expenditure of energy. 



If, however, the animal is to re- 

 new its protoplasm and to store up 

 energy, it must be supplied with 



