The Lettsomian Lectures on Anaemia: Its Pathology, Symptoms, and Treatment
Authors: S. Mackenzie
Journal: BMJ (1891)

produced artificially, it is accompanied by a, at any rate, closely correspondling rise ini the number of the blood corpus- eles-Ilayem states that the specific gravity depends on the corpuscular rielhness of the blood--tlie difference possiblv being causeil lby the passare of a certain amount of plasma inito the lym-lplh spaces.Oin the other hiancd, we find that whlile the density remiains unlaltered, eveni uinder abnormal circum- stances, the nuinrber of the corpuscles is practically uniaffected also.These experhiments, theni, takeni together, affor(d evidence in favour of variationis in the naumiber of corpuscles in the blood being largely concernied in lbringing about differences in its specifi(c gravity, particularly as eertaiin other of our experi- mnents, whiclh c(anniot be quoted here, lhave similarly showin a fall in the nunTier of corpus(' les associated wvith a similar fall if specific gravity.Buit pathologically, at any rate, the pro- lemn is evi(lelitly miore complex tlhani would be inferred from the forecgoihic statenicents.Tlius, in a severe case of pernicious Ian?nmia which wa,,is in St. Th'omIias's Hospital, under tIme care i)f D)r.Bristowe.a few mionlths back, the specific gravity of the bloo(d was found( to be 1027 only, wlhile the number of red corpuscles ii a, cuLbic millinetre was slightly over 50000).Now imornial hmumitian plasmia or serum has a specific gravity of 1028, abouit tihe salmle, or a little higher, tlhani that of the enitire bloo(d in this case.The specific gravity of the red corpuscles is also, normally, so much.ighler thlani tlat of the blood and more?particularly, therefore, of the plasma, that evenm suppos- imig that, in this case their density was considerably lessened, as miiay he inferred froai the ease with whliclh.as I lhave slhowin elsewvliere, tlhe corpluscles break down or their li-nmoglobin difflses ouit, still w(e are (driveii to the conclusion that for time bloo(d to slhow so low a density as the case in point, the speci- tic gravity of the l)lIsmna miust be lower still.It was unfor- tuiate that it, was lnot possible, at the time, to determinie accurately tlie specific gravity of the liquior sanguinis in this instance.Under certaim cc infstance, also, we have been al)le to lower the specific gravity of the blood for a lengtlh of time, fronm '5°t o 300, witlhout a, corresponding fall in the number of the cor- pus(cles present in it, so that in tlhese experiments also, an atccount of whliiel is abouit to appear in the Journal of Phylsiobvqq, it woul(d seenm that a considerable dilutioni of the plasilia lha,id been broughlt about.Christison, inoreover, lhas slhowni by the ol(ler metlhods that the (lenisity of the blood serum is sometimiies c mnsi deral dv lowered, more particulatrly ini the early stages of kidnev (disease, whieln thle specific gravity miiay be 1020 or even 1019.It would appear, tlheni, thlat a rise of specific gravity in the bloodl may be the result of tlie.formna- thini of micnv corpuscles,, or of a draining away of a certain part, piarticula4rly thle wvatery portioni of the plasma, suclh as occurs in cholera, or. to a mnuclh less extent, after the use of salinie pur-atives, while a lowverinig of specific gravity, particularly if mrnrked in extent, will alwvaysl aveapatlhologrica asigniificance, althougzh the caiuse inmcy be a somwhat complex one* since, as we have seen, it must be the result of diminislhed specific g,ravity eithler of plaisnla or of corpuscles of a large decrease in thle number cfi thle corpuscles; or, as is most probable, of .allthese factoirs combined. 4 DIi Saccg, 1889, ). 400.l1 (TOTS.10IoTH(Popuilationi, 141,254).-AScarlatina of t Mddil TIt/Pe: Pet Dn.,, attackedl byq aC Diphtheritic Affection.-W1ith a very favouirable death-rate (18.1 per 1,000), a small prevalenice of zymotic, disease, anld a good record of saniitary work, Dr. Aluinby's report for 1889 bears satisfactory comparisoni witli thiose of foirner years.Scarlet fever, thlouglh wi(lespread througlo lt le district, was of so mild a chtlaraicter as to cause only 11 deaths, hut,wlwooping-cough and dliarrlrhcw caused a gre,ater mortality thlian tusuial.Smnall-pox was three timnes in- tO(lduce(l inlto the boroulgh.rwo cass prOve(l fatal.1)iph- tImeria, thliouholi iiot remiiarkably prevalent, was of a fatal type.MLany of the cases were associated witlh sanitary defects amid dalrmpness.In onie lhousehold, wlhere 5 cases occurred froilm drinikiing impure-water, a, pet dog was also takeni ill anid lhad tio lie kzille(l.( inmakilnr a post-ncorteia examination, D)r.MAtimby ftinid a, distinct, false menmbranle attached to the p1hmarynx.