144 



• KNOWLEDGE • 



[Mahch 9, 1883 



spring snowflako is the exact primitive form from which 

 the modern snowdrop is derived. Such survival of parent 

 and derivative types side })y side, the parent remaining 

 unchanged whih) the other lias widely varied, seldom or 

 never occurs in actual nature. There is one particular in 

 which the snowflako on its part has become more highly 

 developed than the otherwise more advanced snowdrop, 

 and that is in the nature of the stamens. The snowdrop 

 stamens are pointed at the end, and arranged in a little 

 cone in the centre of the Hower ; and tliey open hy a long 

 slit down the inner side, after the common fashion of most 

 amaryllids. The snowflake stamens, on the other hand, 

 are peculiarly blunt at the top, where they open by two 

 odd little t<^rminal pores, which give them a very quaint 

 and truncated appearance. This shows that the snowflake 

 is not itself the original ancestral type, but has varied on 

 its side, too, from the primitive ancestor ; and there can be 

 no doubt that the change depends upon some special 

 method of insect fertilisation, though a simpler one than 

 that of the very complex snowdrop. Oddly enough, by a 

 blunder copied over and over again in many books, it is 

 usually said that the snowdrop stamen opens by pores 

 while the snowflake stamen opens by a slit on the inner 

 surface ; but a single glance at the flowers themselves will 

 show at once that the opposite is really the case. 



"OUR BODIES:" 



SHORT PAPERS ON PHYSIOLOGY. 

 By Dr. Andrew Wilson, F.R.S.E., &c. 



No. VII.— THE PROCESSES OR FUNCTIONS OF THE BODY. 



THERE is an animalcule, averaging in diameter the 

 one-five-hundredth of an inch, or thereabouts, found 

 in stagnant pools, and called the Amreha. The name of 

 the animalcule is derived from the Greek for " change." 

 In appearance it is a mere speck of living jelly, which is 

 ever changing its form — ever flowing, so to speak, from 

 one shape to another. The living matter whereof the 

 amoeba consists is called protoplasm. This substance 

 closely resembles white of egg (or albumen) in its chemical 

 composition. It is the one substance which seems to be 

 inseparable from life ; or to put it more exactly, life is 

 nowhere known or heard of except as exhibited by some 

 form or other of " protoplasm." Whatever may be the 

 relations of protoplasm to life — a topic I need not discuss 

 here — this much is assured, that life, as we know it, seems 

 to require protoplasm or albuminous matter for its exhi- 

 bition and mere existence. Protoplasm, in this way, 

 becomes truly the " clay of the potter," woven by the 

 powers that be into the wondrously varied warp and woof 

 of living beings. 



The Amccba, then, is a protoplasm-speck. It takes in 

 food particles by any part of its frame, and it appears 

 capable of digesting them in any part of its body. 'I'here 

 is no mouth, stomach, heart, breathing organs, or nervous 

 system. Yet the animalcule lives, and lives as perfectly 

 in its own simple way as the man. There seems, indeed, 

 a wide gulf betwixt humanity and the Amceba, but it is a 

 gulf that is by no means impassable, when we consider 

 that a community of likeness (in the essential nature of 

 their living parts) and a sameness of function (in respect 

 of the actions of life) characterise this lower form of life 

 and the sphere of human hopes and fears. We shall have 

 to refer hereafter to the Anicelia as a type of a considerable 

 number of actions which the physiologist studies in man, 

 and it will servo a good purpose if we, therefore, bear the 



humble denizen of the pool, with its soft protoplasm body, 

 clearly in mind. 



Every living lieing — animal or plant, monad or man — 

 performs three grent functions in the course of its existence. 

 The physiology of any animal or plant can be summed up 

 in the expression, that the whole lousiness of life, so to 

 speak, consists of three great processes, which include 

 many minor processes within their limits. There is, firstly, 

 the function of Nutrition, whereby the animal or plant 

 nourishes itself, digests food, and repairs its ever-recurring 

 waste. Then, secondly, succeeds the process of Innervntviu 

 or Relation. Through the exercise of this latter function, 

 the living being brings itself into "relation" with the outer 

 world by means of its nervous system. To the discussion 

 of the functions of the nervous system, this second depart- 

 ment of physiology is, therefore, devoted. But hosts of 

 animals and plants die daily. Continually the units of a 

 race perish and drop into the grave. Hence a tliircl 

 function — that of Eeprodurfion — renews the race, just as 

 " nutrition " renews the indiridiial. New animals and 

 plants are thus brought into the world to take the place of 

 their fellows that have succumbed in the battle of life. 



It is clear that whilst these three functions represent the 

 collective type of the animal or plant, there must be many 

 subdivisions of each action or duty. For example, the 

 function of nutrition includes every action through which 

 the individual body maintains its place in the world. Under 

 this single head what subjects fall to be considered ? The 

 reply is — firstly, foods ; then digestion — itself a compre- 

 hensive topic ; then the hlood, into which food is convert* d ; 

 next circulation, which distributes the blood to all the 

 tissues of the body ; and then comes excretion, or the getting 

 rid of waste matters. This latter duty is performed liy 

 lungs, skin, and kidneys, so that the single word excreti- n 

 stands for and implies the functions of breathing, of 

 the skin, and of the kidneys respectively. Of the other 

 two main functions of the body, the same remarks hold 

 good. Each function is susceptible of division into a 

 large number of lesser actions and details. The so-called 

 " life," then, of a human being may, without any straininrr, 

 either of physiological language, ideas, or facts, be descri' 'od 

 rather as a series of " lives," than as one life. And this 

 latter contention becomes plainer when we reflect that in 

 our blood, as well as in other fluids of our frames, there 

 are " cells " or minute living particles, which certainly 

 possess a power of motion independent of the body of 

 which they form part, and which also exhibit a vitality 

 that is not dependent upon the frame, through whose 

 blood-vessels they perpetually travel. 



For our present purpose, however, it must suffice that 

 we regard the varied processes and actions of the body as 

 existing in a close unity which lies on the surface of things. 

 Health and a truly enjoyable life are only possible to us 

 when this unity is maintained. Derangement of one 

 function is apt to cause aberration of many functions ; and 

 we can only live a perfect and healthy life, physically, 

 when every organ, part, and tissue co-operates with its 

 neighbours in the maintenance of the whole bodily existence. 



Our first consideration must be devoted to the considera- 

 tion of the function of nutrition. It is only natural that 

 we should first seek to know how our bodies are nourished. 

 Why they are nourished we have already seen. Waste and 

 wear are inseparable from existence. Every act of life 

 means the wear and tear of the organ which works. 

 Hence, it is to repair and renew the perennial waste which 

 the living body undergoes, that nutrition devotes all its 

 energies. 



The means whereby we repair waste are largely summed 

 up in the words food and digestion. Food is the material 



