Dec. lo, 1885] 



NA TURE 



A brief survey of the life of a corpuscle of protoplasm 

 as exemplified in an Amoeba follows, and attention is 

 directed to the constructive and destructive inctabo/ism 

 going on in the substance of such an organism. There 

 are anabolic and katabolic changes in that substance, 

 which may be compared to a double flight of stairs leading 

 up to and down from a hypothetical summit ; that summit 

 is what we mean by protoplasm, but whether the term 

 should include a few of the steps up or down or be limited 

 to the top plane cannot at present be decided. 



This protoplasm of the unicellular organism exhibits 

 properties which may be classed as (i) Assimilation; (2) 

 Contractility J (3) Irritability or Sensitiveness. From the 

 consideration of these we are led on to that of a simple 

 multicellular organism — a Hydra — in which a first stage 

 of differentiation of these properties between two groups 

 of cells — the endoderm and the ectoderm — is observed. 

 Then in due course the further differentiation of these 

 two primary groups of cells in a higher animal is traced 

 — in an account of the organs and tissues with their 

 specialised properties and functions derived by gradual 

 modification from the lower stage of differentiation. 



The relation of the complex organs, composed of 

 numberless cell-units, of a higher organism to the prac- 

 tically homogeneous protoplasm of a single cell-corpuscle 

 having thus been traced, Dr. Foster takes one organ 

 of a higher animal — the kidney — as an example of the 

 problems which present themselves to the modern physio- 

 logist. There are, he points out, two points of view, two 

 aims of inquiry which pursue in many respects different 

 methods, though ultimately blending and tending con- 

 jointly to the explanation of the action of the kidney. 

 They are distinguished as the "mechanical" and the 

 " molecular," and correspond in these later days to the 

 earlier and later standpoints of physiology represented 

 by the doctrine of organs and the doctrine of cell-sub- 

 stance. The physiologist's inquiry is sketched from the 

 first point of view, and it is pointed out that this inquiry 

 "takes on to a large extent the characters of an attempt 

 to unravel an intricate game, in which the counters are 

 nervous impulses, muscular contractions, and elastic re- 

 actions, but in which the moves are determined by topo- 

 graphical disturbances and mechanical arrangement." 

 The second kind of physiological inquiry into the kidney 

 ignores for the time being these grosser conditions, and 

 is directed to the molecular action of the protoplasmic 

 cells which build up the distinctive structure of the 

 kidney, namely, its tubules. 



Reverting to "a brief survey of the whole field of 

 physiological inquiry," Dr. Foster says : — " The master 

 tissues and organs of the body are the nervous and mus- 

 cular systems, the latter being, however, merely the 

 instrument to give expression and effect to the motions 

 of the former. All the rest of the body serves simply 

 either in the way of mechanical aids and protection to 

 the several parts of the muscular and nervous systems, or 

 as a complicated machinery to supply these systems 

 with food and oxygen, i.e. with blood ; and to keep them 

 cleansed from waste matters through all their varied 

 changes." 



That, no doubt, is true if the organism be viewed 

 as an individual and not from the point of view which 

 regards the individual as one of a race and the race 



as part of the general outcome of organic develop- 

 ment, and this as again a part of a more general pheno- 

 menon. The biologist who takes his stand on the doctrine 

 of evolution must, we venture to think, regard as the 

 " master-tissue " over and above those indicated by Dr. 

 Foster — the reproductive tissue or the specific cells of the 

 ovary and testis. It is in every animal this little nest of 

 germ-plasma handed on from generation to generation 

 with scarcely a change which receives the homage and 

 service of all the various products of dilTerentiation of 

 its brother-cells. The latter are but the carriers, pro- 

 tectors, and servants in the struggle for existence of the 

 undifferentiated germ-plasma — even the cells concerned 

 in thought and reason exist but to protect the germ-cells. 

 The former perish as a mere husk whilst the germ-plasma 

 is immortal ; it forms, by growth and fission, on the one 

 hand, new germ-plasma which never dies, and on the 

 other hand protecting tissue-cells, which have only an 

 evanescent existence. As Dr. Foster himself has else- 

 where said : — " The animal body is in reality a vehicle for 

 ova, and after the life of the parent has become poten- 

 tially renewed in the offspring the body remains as a 

 cast-off envelope whose future is. but to die." 



In the latter part of the article our present knowledge 

 of the nature of protoplasm, and of the processes which 

 go on in connection with it, is forcibly sketched. Different 

 kinds of protoplasm are recognised, the differing qualities 

 of which are to be regarded by the biologist as "the 

 expression of internal movements " of the molecules of 

 the protoplasm. The term " mesostate " being used to 

 express those ascending and descending steps of the 

 pyramid whose summit is protoplasm, and " anastate " 

 and " katastate " corresponding respectively with those 

 constituents of cell-substance which are on their way to 

 attain, and those which are falling away from the state of 

 perfect protoplasm, we find that the tendency of inquiries 

 into the molecular processes taking place in living 

 secreting cells, in muscular tissue, and in the various 

 forms of nerve-tissue, " is to lead us to regard the varied 

 activities of these tissues as due to molecular disruptive 

 changes in their several katastates, these being various 

 stages of the downward metabolism or katabolism of pro- 

 toplasm." 



Hering's recent speculations on the relation of colour 

 sensations to the condition of the protoplasm of the per- 

 cipient cells lead, Dr. Foster thinks, to a new molecular 

 physiology. He gives us the hope that by an application 

 of Hering's conceptions (which the limits of our space do 

 not permit us to notice more fully) to other groups of 

 protoplasmic units a new departure may be effected, and 

 that we may look forward to a very great advance in our 

 knowledge of the nature of the processes taking place in 

 living cells. 



Dr. Foster concludes his article with an outline of the 

 methods of physiological inquiry and an unanswerable 

 though brief exposition of the dependence of the progress 

 of physiology upon experiment on living organisms. 



The article on Pianoforte is of considerable interest for 

 several reasons ; first, because it is signed with the initials 

 of Mr. A. J. Hipkins ; secondly, from the number and 

 felicity of the illustrations ; thirdly, because it takes up a 

 special and somewhat neglected point in the history and 



