November 7, 19 12] 



NATURE 



!8l 



LETTER TO THE EDITOR. 



[The Editor does not hold himself responsible for 

 opinions expressed by Jiis correspondents. Neither 

 can he undertake to return, or to correspond with 

 the writers of, rejected manuscripts intended for 

 this or any other part of Nature. No notice is 

 taken of anonyinous communications.] 



The Jaw from the Stalagmite in Kent's Cavern. 



It is remarkable thai so Ihtle notice has been taken 

 of the important discovery by Mr. Pengelly ot a part 

 of a human upper jaw in the granular stalagmitic 

 laver of Kent's Cavern, and even more so that some 

 well-known anatomists appear to have been unaware 

 of its existence. 



If the deliberate evidence of Pengelly, who for so 

 long so carefully and scientifically explored the floor 

 of the cave, is not to be accepted on this point, his 

 whole investigation will be rudely shaken. It is much 

 to be regretted that Pengelly 's pamphlet entitled "The 

 .\ncient Cave Men of Devonshire," containing a most 

 clear resumi of his exploration, is not better known 

 and more easily procurable. It would be most advan- 

 tageous if it could be republished. On p. 9 of this 

 pamphlet Pengelly writes as follows : — " The objects 

 in the modern stalagmite were not numerous. They 

 consisted of charred wood, marine and land shells, 

 remains of various mammals, including the extinct 

 cave bear, cave hyena, tichorine rhinoceros and mam- 

 moth ; well-rounded pebbles of various kinds ; flint 

 flakes, implements, and cores ; and a portion of a 

 human upper jaw containing four teeth, with a loose 

 tooth lying near it. Some of the remains of each of 

 the e.xtinct animals were not only in quite the upper- 

 most portion of the stalagmite, but were not com- 

 pleteU" covered with it. The human jaw was near its 

 base, where it was twenty inches in thickness." 



From this it is clear that extinct animals were living 

 in Devonshire up to the very end of the period during 

 which the upper stalagmite was being deposited; and 

 that this must have been some considerable time after 

 the jawbone became embedded in the lowermost layers 



of it. E. A. P.A'RKVN. 



October 29. 



TUBERCULOSIS AND THE MILK SUPPLY. 

 A TTENTION has been directed to the relation- 

 -^ *■ ship of tuberculosis and milk, and to the 

 problem of a pure milk supply and the methods 

 whereby this may be ensured, by a series of 

 articles and letters which have appeared in The 

 Times during- September and October. We may 

 consider the questions thus raised under three 

 heading's : (i) how far is tuberculous-infected 

 milk a danger to the community as a whole; 

 (2) will pasteurisation, certified milk depots, or 

 other means remedy the evil if it exist; (3) can 

 a safe milk supply he ensured without revolution 

 in present methods. 



I. The menace, if it exist, of tuberculous milk 

 chiefly falls upon children from one to six or seven 

 years of a^e, i.e., when cows' milk forms a staple 

 article of diet. There can be no risk to the breast- 

 fed infant, but, unfortunately, the natural method 

 of infant feeding- is at present out of fashion ! 

 While it is true that tulsercle bacilli have been 

 found in some 10-20 per cent, of all samples of 

 milk examined, and while the experiments of the 

 Royal Commissions on Tuberculosis and of others 

 NO. 2245, VOL. 90] 



have shown that tuberculosis may be communi- 

 cated by feeding with tuberculous milk, the amount 

 of human tuberculous infection derived from milk 

 is still uncertain. The pulmonary ("consumption," 

 phthisis) is the most frequent form of human 

 tuberculosis, the death-rate per 100,000 living for 

 1901-1909 being 117, as against 50 for all other 

 forms of tuberculosis. 1 



Now Bulloch,- from a very careful survey of 

 the literature of the subject, comes to the con- 

 clusion that pulmonary tuberculosis is produced 

 almost always, if not exclusively, by tubercle 

 bacilli of the human type. More than two-thirds 

 of human tuberculosis is, therefore, certainly not 

 due to the bovine bacillus or to milk infection. 

 Bulloch further remarks that the bovine tubercle 

 bacillus plays a relatively unimportant role in the 

 production of tuberculosis in man ! But it may 

 be objected that, inasmuch as 10-20 per cent, of 

 milk samples contain tubercle bacilli, there must 

 be grave risk of infection therefrorn. It will be 

 found, however, that the percentage of infected 

 samples is much lower than this for milk obtained 

 under reasonably good conditions, such as those 

 under which the large dairy companies get their 

 supplies. Again, the method of detection of the 

 tubercle bacillus employed in the examination of 

 milk samples is by the inoculation of guinea-pigs 

 (not ingestion or feeding), after concentration of 

 the bacilli by centrifuging. 



Many experiments prove that inoculation is 

 a method of infecting infinitely more certain than 

 feeding. Probably not more than twenty tubercle 

 bacilli are required to produce a general infection 

 in a guinea-pig by inoculation, whereas Findel 

 found that doses of 19,000-312,000 bovine bacilli 

 did not infect by feeding, and Reichenbach esti- 

 mated that a dose of no fewer than 140 million 

 bovine bacilli was required to infect guinea-pigs 

 by feeding.^ It is well known that tubercle bacilli 

 are scarcely ever detected by microscopical 

 examination in mixed milk, which gives a positive 

 result with the inoculation test ; yet, if they were 

 present in anything like the numbers necessary to 

 infect by feeding, they should be easily detected 

 thus, for of every 100 organisms present, 1-2 should 

 be tubercle bacilli ! The fact is, we have no data 

 indicating the. infectivity by feeding of ordinary 

 mixed milk. 



The work of the Royal Commission gives no 

 information on this most important point, for in 

 all their experiments on the transmission of tuber- 

 culosis by feeding, huge doses of bacilli were 

 administered. Although, of course, every effort 

 should be made altogether to exclude tubercle 

 bacilli from milk, it may well be doubted if the risk 

 of infection from ordinary mixed milk is anything 

 like as great as has sometimes been suggested, 

 and the expensive and harassing machinery some- 

 times formulated to accomplish that end would 

 probably benefit the stockman far more than the 

 general public. 



1 Rep. Med. Officer Local Gov. Board for 1910-11. 



2 Horace Dobell Lecture, iqii. 



:• See McFadyean, Journ. Roy. Inst. Pub. Health, December, igro, pp. 

 7i5and7iS. 



