NA TURE 



[July 12, 190b 



Abyssinia, he seems to indicate, and with much more 

 probability, political dangers from the effervescence of 

 the Abyssinians themselves. Before long the adjacent 

 regions of the Egyptian Sudan promise to become 

 exceedingly prosperous with their fertile soil and 

 accessibility through British-made railroads or river 

 navigation. Mr. Hayes seems to anticipate that this 

 coming prosperity may be a source of temptation to 

 the reckless mountaineers of western Abyssinia, who 

 can reach the Sudan so much more easily than the 

 Sudan can vanquish Abyssinia. 



In his desire to give an accurate picture of 

 -Abyssinia, both at the present day and at previous 

 periods, the author quotes extensively from earlier 

 writers, with acknowledgment, and, where the works 

 are recent, by direct permission. These extracts, 

 coupled with his own shrewd and accurate observ- 

 ations, make up a most readable and, perhaps it may 

 be said, valuable description of Abyssinia. There is 

 a good deal of new information about Abyssinian 

 Christianity, coupled with some admirable photo- 

 graphs of frescoes in the interior of churches. The 

 author's remarks on pp. 56 and 59 on the soil created 

 by the work of the white ant, and the washing of 

 this soil down from the highlands of Abyssinia to 

 the lowlands of Egypt and the Sudan, are distinctly 

 interesting. There are one or two trifling mistakes 

 which should be corrected ; for instance, in the text 

 and illustration on p. 184, a fine specimen of a reed- 

 buck antelope is described as a " hartebeest. " It is 

 interesting to note that, so far north as the valley of 

 the Atbara, such a typical specimen of the reedbuck 

 should be found. 



The author and the authorities whom he quotes 

 somewhat extensively give an interesting description 

 of the Falashas, the so-called black Jews of central 

 Abj'ssinia, the region round Lake Tsana. The 

 Falashas are undoubtedly Jews in religion, and have 

 been for many centuries; but great caution should 

 be exercised by people who desire to write with scien- 

 tific accuracy in identifying these people of Semitic 

 origin with the ancient Israelites of Palestine. It is 

 alleged that the traditions of these Falashas would 

 make them the descendants of a branch of the Jewish 

 people which had never known Palestine, but had 

 migrated to Abyssinia direct from Egypt. Such 

 theories as this are hardly worth discussing by the 

 scientific ethnologist. The Children of Israel w^ere 

 undoubtedly an .Arab tribe that originated in the 

 region between Syria and Egypt. Their monotheistic 

 religion spread far and wide through the centuries into 

 Arabia, .Abyssinia, and North .Africa; and, elsewhere, 

 in the form of Christianity. The Jewish people that 

 were expelled from Palestine by the Romans were a 

 very composite race, containing a good deal of 

 Armenian blood. It is possible that the Falashas, like 

 other tribes of " black Jews " elsewhere, adopted the 

 Jewish religion at some period before the spread of 

 Christianity or of Islam, but are not directly de- 

 scended from any section of the original Jews. 



H. H. Johnston. 



OPSONINS AND TUBERCULOSIS.' 



AITHEN the scientific researches of Durham, work- 



* * ing in Gruber's laboratory, revealed in 1895 the 



presence of agglutinins in the blood, the discoverv was 



soon put to practical use in clinical medicine by Widal 



I " On the Diagnosis of Tuberc)e hv the E.vomiration of the Blood, and 

 Spon'aneoii. Pharorylosis," By Dr. A. E. Wripht and Staff-Surgeon 

 (Proc Roy. Soc, B., vol. Ixxvii., 7906.) 



taneous Phagocytosis, and on the Phagocytasis which is 

 Heated Senim of PMients who have responded to 

 n, or, as the case may be, to the Inoculation of a 



NO I915, VOL. 74] 



R.N. 



" On Sp. 



obtained with thf 



Tubercular Infect 



Tubercle Vaccine.' 



and Griinbaum, who showed what valuable aids these 

 substances were in the diagnosis of typhoid fever ; 

 further, and this does not seem to have been so 

 generally recognised, the}' have been shown to be of 

 service in the prognosis of that disease. A similar and 

 no less important practical use in the diagnosis of 

 tubercular infections was made by Wright and 

 Douglas (Proc. Roy. Soc, vol. Ixxiv.), and is here 

 further developed by the former in conjunction with 

 Staff-surgeon Reid. The method employed is the 

 estimation of the opsonic power of the serum ; and 

 the technique is that described by Drs. Wright and 

 Douglas in a previous paper (Proc. Roy. Soc, vol. 

 l.xxii.). This briefly consists in incubating for fifteen 

 minutes at body temperature a mixture of equal 

 volumes of washed blood corpuscles, bacterial suspen- 

 sion, and the serum under investigation. Blood films 

 of this mixture are prepared and appropriately stained, 

 and the phagocytic count is estimated and compared 

 with the result attained by conducting the same ex- 

 periment with normal serum, such serum being 

 obtained by pooling the blood of a number of healthy 

 individuals. The phagocytic count of the experiment 

 conducted with normal serum is taken as unity, and 

 the result of the other count as compared with this 

 gives the opsonic index of the serum under investi- 

 gation. 



In the recent paper the authors first give the result 

 of a large number of blood examinations in generalised 

 and localised tubercular infections. Two very im- 

 portant facts are the outcome of this work : — 



(a) That in localised tubercular infections the opsonic 

 index is uniformly low. 



(b) That in cases of tuberculosis associated with 

 constitutional disturbances the index is continually 

 varying, the patient living a "life of alternating 

 negative and positive phases," that is to say, the 

 resistance of the blood is reduced as an immediate 

 effect of the bacterial poison and then increased above 

 the normal in response to the infection. 



Further, ample evidence has accumulated substan- 

 tiating the fact already enunciated that normal sera 

 do not vary more than ten per cent, on either side of 

 unity. 



-Applying these principles to the practical diagnosis 

 of tubercular infections, it will be obvious that much 

 value will accrue from a series of examinations of the 

 blood, and to a less extent from a single examination. 

 Where a series of measurements of the opsonic power 

 of the blood reveals a persistently low opsonic power 

 with respect to the tubercle bacillus, it mav be in- 

 ferred, in the case when there is evidence of a localised 

 bacterial infection which suggests tuberculosis, that 

 the infection in question is tubercular in character. 

 A continually fluctuating index would point to a 

 tuberculous infection associated with constitutional 

 disturbances, whilst an index which never varied on 

 either side of the normal to a greater extent than ten 

 per cent, would be taken as evidence against a tuber- 

 cular infection. 



If only one examination of the blood is possible 

 and the index is found to be low, then according to 

 the evidence in the case under investigation of a local 

 bacterial infection or of constitutional disturbances, it 

 may be inferred with probability that the infection is 

 of a tuberculous nature. A high index would be 

 taken as evidence of a svstemic tuberculous infection 

 which is active or has recently been active. But no 

 inference at all, either positive or negative, is 

 warranted if on a single occasion the tuberculo-opsonic 

 index be found to be within normal limits. In this 

 case, however, it is possible bv employing a further 

 test to arrive at a diagnosis. This consists in repeat- 

 ing the experiment after having heated the serum for 



