Remarks on Nutrition and Growth
Authors: D. J. Hamilton
Journal: BMJ (1883)

WiA'T is meant by the terms " nutrition and growth ?"How are wv to define them in strictly scientific l4nguage, and.whatbis the rp- latibuship of the oie to the othe.r:?Stuchl are questions which have often!pnzzle the biologist,-and have led-some (Sachs-Text-Rook of Botany, translatedl by Beninett and Dyer, p. 693);to supposb that it is itfipossibl4.to@,deflncthe-meaning of growth in strict terms; which.wihlbe opplbe Lo all cases.I amn far frorm takig this view of the giatten, a4ud-w*nuld~look-upon the growth -of ananimal or ;veg-et- ablb orgaslism as a definite process, limited in exctn by .eert&aniren.coglillabie laws, and due t-sp ctroperties 1inhereiit-in the tissues.. tots jier I-h~b eiidbavouted to tiace-thtpesses ofgrowth andI utrition as -far back as it seems to me oiur .presentJkiowledge -.. A-..; I .. .. .-wifllpermitof.Indoing so I have been chiefly actuatWby ,gesire; to form some sort of a basis for the rational-d&fnlition of-the condi- tis; of 'hyprtroqph or atophy.Preperly-seal).dfV~hil-tobe&1onsidered along wit-h arty wbrk on groth; tut, iii this method: of lroatrment sPigl, in lhe presnt instan e, cbiiiplicate nt'es I- has-ve c6nsidered it better to limit the scope of the paper to the subb- jethfs f' hiutrifiot anhdgro6Wth aIone.gAte¢,ltiy lMdrt~tion.-Therequirements for the maintenance of a- hiealthy state of nutrition, I hold, are twofold: l, essential, 2, accessory.. 'I, .sse,~tialsof2Vutqrtion-Main, and the higrher vertebrates, are far, too compiex organisms t6 study t'he essentials of nutrition in.In order to, understand-what -the bare necessaries for the proper n6firtihiment of an 'njt-al or yIgetble are, "ve 4'st go much lower in tli1scale.it ii tle loWest menibers of each kingdom that we can best peerceive what the rudiments of a ntkritive apparatus are.-a4.the aniimal kingdom the, protozoa, and iiibre .,especially the class of naked rhizopoda, are specially suited for this purpose.,The most of these are simple masses of protoplasm, sometimes surrounded bya lightly differentiatedcovering, sometimes not.The amoeba is one ofthe best examples; So far as e know, this organism possesses neither formeed channels for the conveyance of nutrition, nor any- thing comparable to even the most elementary nervous system.Yet it noiUrishment seems to proceed with perfect regularity.The nu- trltlveh .alu.9tinply b Irought in contact with its protoplasm as minute particles of organic -matter.These are taken into its sub- staulce by;a process of invagination, and the materiaIs suited for the noutishmient o£'the animal are extracted from' them,.therefuse non- assimilable substances being rejected by a reversal of the process by wlihich they-.were absorbed.-The same primitive means of obtaining -noftiishment -prevail in the lowest members of the vegetable kingdom.Like the protozoa, they are essentifally masses of protoplasin, and they obtain their food in the starie way, namicly, by the ingestion of-organic fragments ofvarious bodtes -vhih may lie in their neighbo'urhood.These are digested and assimilated, and the refuse material rejected.It is hardly necessary tq say that' like the amoeba, they do not possess an$, definite channels for the conveyancQ of nutriti,-nor is there anyt'hing to representa nervous system.Some of the best examples of these low vegetable organisms are to be found in the myxomycetes.Thev consist, in a certain stage ot'de'velopitnt of 'an ameaba-like mass of protoplasm or plasmo.(ium, which has the power of locomotion.by alternately shooting outwards and retracting lobes of its protoplasmic substance.These rmbsses of vegetable protoplasm nourish.themselves in the same manner as the protamoeba.According to De Bary (" Morphologie undt Physiologic der Pilze," in Hofmeiister's Pkysiologische Botanik; and ."-DieMyxxonycetes," Leipzig, 1874), oneoften observes foreign b9dies in the interior of the plasmodia, consisting of fragments of (16as1 plant-cells, spores of fungi or of myxomycetes, granular mat- tor, or particle?ofooloured substance, when such have been placed neat thliem.' Thesefragments -of foreignmatter are laid hold of by quite awell-defined tnov-ement.The surface of the plasmodium raijsqs itself' upwarits into.a little tumour-like mass beneath' the l)OV whlichl isrestingupon it.The edgesiof this tumour-like projee- tion then gradually flow over, and finally enclose, the little nutritious.particle.It is not to bke supposed, however, that the foreign bodies lie naked and simply imbedded in the plasm'odium.kround them- there forms a little vacuole or cavity similar to thit 'which sur- rounds the ingesta of infusoria-thde so-called"stomach-vesicle."The materials, if of, the proper composition, are gradually dissolved, and the.indigestible refuse is thrown out of the plasmodium by a reversal of the means by which the particles were absorbed.The