October 27, 1923] 



NA TURE 



62 



the strictest observance of the methods of modern 

 archaeology. 



Through this discovery we now know definitely that 

 the Boskop race preceded the Strandlooper race 

 historically. They perhaps owed their extinction to 

 the latter^ the Solutrian culture of which (so ably 

 examined by Dr. L. Peringuey,^ the Director of the 

 South African Museum) indicates familiarity with the 

 uses of the bow. We know further that the Boskop 

 specimen was no human freak, but a type representative 

 of a race once widely distributed in South Africa from 



■ " The Stone Ages of South Africa," etc. Annals of the South African 

 Museum. Vol. viii. July 5, 1911. 



the Transvaal to the remotest south-eastern comer of 

 the continent. 



The implements, culture, and aesthetic achievements 

 of these big-brained men of pre-history still remain to 

 be discovered. Their employment of ochre in their 

 burial rites indicates their familiarity with pigments 

 and the artistic and symbolical uses to which they 

 might be put. The remarkable parallelisms between 

 the so-called " Bushman " art and that of Cro-magnon 

 man in Europe was insisted upon by Sollas many years 

 ago, and the evidence may yet be forthcoming which 

 will conclusively solve the fascinating yet elusive 

 problem of their correlation. 



Insulin and its Value in Medicine.^ 



By Prof. J. J. R. Macleod, F.R.S. 



CARBOHYDRATES are essential in the chemical 

 processes upon which life depends. Not only is 

 the glucose, the form in which they are mainly absorbed 

 into the blood, the source of muscular energy, but it is 

 also in some way necessary in the oxidation of fats. 

 Preceding its oxidation, glucose undergoes a series of 

 preliminary changes which proceed step by step in such 

 a manner that a long series of intermediary substances 

 is formed ; and when anything interferes with the 

 process at any stage, as in diabetes, glucose accumulates 

 in the blood and tissue fluids, causing the main early 

 symptoms of the disease, hyperglycsemia and glyco- 

 suria. Later involvement of the oxidation of fats 

 results in the accumulation of the ketone bodies in 

 the organism, and these, by their toxic action, cause the 

 often fatal condition of coma. 



The control of this process of carbohydrate meta- 

 bolism has for years been assumed to be the function 

 of a hormone derived from the Isles of Langerhans of 

 the pancreas. Although the existence of this hormone 

 was fairly certain, little success resulted from attempts 

 to extract it in potent form from the pancreas, 

 probably because it was destroyed by the powerful 

 digestive enzymes also present in such extracts. 

 IJantiim and Best circumvented these by making 

 extracts of the degenerated residue of pancreas follow- 

 ing ligation of the ducts, it having previously been 

 shown that in this residue the islet cells are more or less 

 intact but the external secretory cells are largely 

 degenerated. The extracts were found to remove the 

 two chief symptoms of diabetes in depancreatised 



dogs. Alcoholic (xt I at 

 also found to contain iln 

 tinued u.se it was possible 



,i;..iw.i;,-:.,Mn,.i-. I. i;. ( -n 



It!, 



dult beef pancreas were 

 nnone, and bv their con- 



'HiMrialily t(i prolong the 



M, t i, n ^lurceded 



(iding 



irrit.ll lii;.: MiiiM.i 111 rS, SO 

 ly injected into diaiutir 



life of t 



by fra' ;i 



these ail I tr rvi 1,1. i ul 



thai th(\- ((iiild he repealcf 

 patient 



With ;i)j)Ues of insulin a\ailahle, it was now 



possible to show that it removes all ot the ohservaMe 

 symptoms of diabetes in depancreatised do^^s. i hus.not 

 only did it cause glycogen to become deposited in large 

 quantities in the liver when sugar was fed to the animals. 



> A 1. 



.'\sso<i.ili' 



if Physiology of the British 



NO. 281 7, VOL. I 12] 



the first analysis giving more than 20 per cent, of this 

 substance (J. B.C.), whereas without insulin traces onlv 

 are found, but it also caused the respiratory quotient 

 (ratio between CO2 and Og in respired air) to become 

 raised. These results were soon confirmed on diabetic 

 patients. In more recent work, in which depancreatised 

 dogs were given insulin daily along with considerable 

 quantities of carbohydrate, life has been prolonged 

 for over four months, and by careful comparison of the 

 sugar balance of the animals it has been found, bv 

 F. N. Allen, that a small amount of insulin is capable 

 of causing relatively much more glucose to be meta- 

 bolised than when a large amount is given. Or, in 

 other words, the glucose equivalent per unit of insulin 

 is much higher with .small than with large doses. 



Although there can be no doubt of the high thera- 

 peutic value of insulin in the treatment of many cases 

 of diabetes, its value as a new instrument for the 

 investigation of problems of metabolism other than 

 those relating to this disease is also high. Evidence 

 for this belief is founded, among other things, on the 

 striking effects of insulin on normal animals. When it 

 is a(hiiinistered to rabbits, for example, the first efifect 

 is a very rapid lowering in the percentage of sugar of 

 the blood — first observed by J. B. Collip— and when 

 this reaches a certain level symptoms of a peculiar 

 nature supervene. These consist usually of violent 

 convulsive seizures each lasting for a niimitt' or so. and 

 of a gradually increasing state of coma, with fall in 

 body temperature, endinjj oftt n in dtath from respir- 

 atory failure. Symptoms ol a similar (ha meter occur 

 also in other animals, includini: man. after large doses 

 of insulin. 



The symptoms were found to be dependent on the 

 lowerint: of blood sugar ; thus, they usually supervene 

 in nornially fed animals whtn the blood sugar has 

 fallen to about 0-045 P*'' ' < '>t., and they are removed 

 iniineihately \^\ the addition of glucose to the blood 

 either h\ adminislerini; tliis sugar subcuta^ ' or 



l)y ( ansin'4 it to be lilxrated in the body fnu; . n. 



as h\ the injection ot adrenalin (epinephrin). it was 

 lonnd. nionoNcr, ihal. ol all the sugars, glucose alone 

 has an inunediate and la>tin;.: (licit. e\cn Icaxnlose 

 and galactose, \\ hich are its neai(>t neii:hiionix, ha\ ing 

 onK a :du'l)t .ind tian->itoi\ ait ion. 



.Mthuugh the s\-nipt()nis I oniniiiiil\ .n . m- in \\(11 i,,! 



