DISCOVERY 



103 



beings, has been transmitted. Even influenza, in 

 spite of the American claims which have lately been 

 widely published, is still on the doubtful list. Many 

 believe that a bacterium called after Pfeiffer is the 

 real culprit. But filter-passers offer a very special 

 problem, since in two instances — in small-pox and in 

 hydrophobia — instead of the tiny filter-passer, much 

 larger bodies, known as the Guarnieri bodies and the 

 Negri bodies respectively, are found in the organs of 

 the dead animal after injection of a filter-passer. 

 They are too big to pass a filter ; we shall return to 

 them later, and see how they may be related to the 

 filter-passer. 



For the moment we must remember that bacteria 

 are not the only creatures whose presence in the human 

 body brings disease and death. The protozoa form 

 another group, the first and tiniest animals, as the 

 bacteria are the first and tiniest plants. Malaria is a 

 type of a protozoal disease. These little animals have 

 a life-history ; unlike bacteria, which exist only as 

 spores or adults, we can parallel in them Shakespeare's 

 seven ages in man. And it is possible that some 

 filter-passers are protozoa, not bacteria. Many 

 protozoa can, at some stage in their history, pass 

 through a filter. It has been stated — and, as in the 

 case of nearly every statement which can be made on 

 this difficult question, it has been denied — that the 

 protozoon found in sleeping sickiaess can pass a filter 

 during some of its stages. And when we come to 

 examine the reports of those who claim to have grown 

 a filter-passer in a test-tube, we find that they are not 

 identical. In some instances, as in infantile paralysis, 

 the familiar tiny, nameless speck is seen. In others — 

 notably in Noguchi's description — an oval object, with 

 a central body or nucleus, was seen. Such a descrip- 

 tion is unlike a bacterium, but very like a protozoon. 

 And then we find the Negri body — a group of tiny 

 specks in a surrounding envelope — in the brains of 

 dogs dead of hydrophobia. That may be another 

 stage in the filter-passer's history. And another fact 

 is very suggestive. How is it that by giving a man 

 cow-pox — a distinct disease as far as symptoms go — 

 we can excuse him from the necessity of having small- 

 pox ? Such a state of affairs is unique in medicine. 

 The suggested answer is that cow-pox is caused by one 

 stage of a protozoon ; small-pox by another. Varia- 

 tion in the stages which protozoa achieve in different 

 animals is well known — even in malaria the parasite 

 is in a different stage in the mosquito and in man. 



Some Special Filter-passers 



It is pleasant to relate that filter-passers are not 

 always our enemies. A remarkable theory is put 

 forward by D'Herelle. He believes that he has 

 found a filter-passer which lives, like a parasite, on 



bacteria. He calls it the Bacteriophage, or Bacterium- 

 eater. Space will not permit of a full description of 

 this last example of the law that " Big fleas have 

 little fleas upon their backs to bite 'em," but it has 

 obviously a very important bearing on the question 

 of immunity to disease. 



To make our survey, brief though it is, more com- 

 plete, we must mention the question of malignant 

 growths such as cancer. It has been stated that 

 warts are caused by filter-passers, and warts bear 

 considerable resemblances, from the pathologist's 

 point of view, to cancers. It is well established that 

 a form of cancer in birds and dogs is related to filter- 

 passers. Many years ago large bodies called " Russell's 

 corpuscles " — a harmonious phrase — were described in 

 malignant tumours, and might be compared to the 

 Negri bodies of hydrophobia. But, obscure though 

 the cancer problem is, it is not probable that the 

 solution win come from a study of filter-passers — and 

 " Russell's corpuscles " have long been discredited. 



It wiU be interesting to await the results of the 

 present concentrated attack on the question of dis- 

 temper in dogs, and its relation to influenza in man. 

 Perhaps in a very short while we may see this whole 

 question on a far more secure basis than it is at present. 



REFERENCES 

 Wolbach, Boston Med. and Surg. Jotirn., 1912, p. 419. 

 Noguchi, Journ. Amer. Med. Assoc, 1913. P- 312. 

 Duval and D'Aunoy, Journ. Exper. Med., 1922. 

 Noiweau Trailede Medecine. By many Authors, 1920. Negri 



Bodies and Guarnieri Bodies, 

 Maitland, Cowan, and Ditweiler, Med. Sci. Abstr., 1921. 

 Volpino, Med. Sci. Abstr., 1921-2. 

 Dick and Dick, Journ. Amer. Msd. Assoc, 1921. 

 Hektoen, Journ. Amer. Med. Assoc, January 1923. 

 D'Herelle, 7"/)e Bacteriophage, English translation, October 1922. 



Modem Industries 



I. CEMENT MANUFACTURE ALONG THE 

 HUMBER 



By R. C. Skyring Walters, B.Sc, 

 Assoc.M.Inst.C.E. 



The object of this paper is to describe the cement-making 

 industry in the North Lincolnshire and South Yorkshire 

 coasts bordering on the Humber estuary. 



The raw materials required for the manufacture of 

 cement are those containing 75 to 78 per cent, of calcium 

 carbonate (obtained from certain chalks or limestones) and 

 the balance (25 to 22 per cent.) of silica, alumina, and 

 iron (a constituent of shales, clays, or muds), and the most 

 successful works are those which are situated near both 

 these materials and which can easily obtain good supplies 



