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872 In the matter of natural dyestuffs America has always occupied a leading position. Many of the principal natural dyes are of American origin. Logwood, fustic, cochineal and the red-woods are all American products, discovered in, and still obtained from, Mexico, Central America and South America, as well as the West Indies. During the war a product very closely re- sembling fustic and known as osage orange was also developed in the United States and in 1921 was being produced in con- siderable quantities. As the dyer usually employs the colouring matters of the dyewoods in the form of suitable extracts, there has long been developed in the United States a considerable industry in the manufacture of these extracts, generally pro- duoed in connexion with the manufacture of tannin extracts. This industry is in no way associated with the coal-tar dyestuff business. The great scarcity of dyes during the early part of the war resulted in an abnormal expansion of the dyewood extract industry, which rapidly declined as the manufacture of synthetic or coal-tar dyes increased. In former years natural indigo was extensively used in dyeing, and in early colonial days large quantities of this dye were cultivated in the south. As the grow- ing of cotton increased, that of indigo was neglected, so that most of the indigo used in the United States was imported, chiefly from the Far East. A certain amount, however, had long been obtained from Central American provinces and the West Indies. The advent of synthetic indigo soon displaced the natural product, so that little of this vegetable dye was used in America, although the United States in 1921 manufactured all it needed of this most important dye. After the war, owing to the shifting of the centres of trade, the United States became an important market for the sale and manufacture of furs. This resulted in the building up of an extensive industry in the dyeing and finishing of furs which will without doubt become firmly established as an important adjunct to the general dyeing in- dustry of America. (J. M. M.)

DYSENTERY (see 8.785*). This term is now employed to designate a clinical syndrome characterized by the passage of blood and mucus consequent upon the pathogenic activities primarily upon the large bowel, leading to ulceration of certain animal or vegetable forms of life. The advances in our knowledge of dysentery made during 1910-20 were considerable, and were in great measure due to the combined interdependent efforts of protozoologists, bacteriologists and entomologists in their unremitting investigations and laboratory researches, to their fruitful collaboration with the physician, also to the extensive experience gleaned through the World War. Dysentery as a disease is widespread throughout the world and workers in all continents and many countries have shared in the progress of knowledge of it. This was, moreover, essential, as certain causal organisms amongst the helminths can only complete their life- cycle in the particular regions where their primary host, a lower animal, exists in nature.

Again, climatic factors play a r61e in the incidence of certain types of dysentery; and the organisms, their r&le and specific lines of treatment and prevention, can be best studied where the disease prevails. Thus American workers in Manila firmly established by experiments on condemned prisoners that there is but one, Entamoeba histolytica, of the five amoebae found in man which is pathogenic to him, and finally cleared up the confusion by determining its life-cycle and differentiating it from the E. coli,. an amoeba living also in the large bowel of man.

From Hong- Kong we learned the specific action of emetine, an alkaloid extracted from ipecacuanha, on amoebae; and its ap- plication with such beneficial results to man was first made in India. Though amoebic dysentery was until recently considered a disease of the tropics, and rare in temperate countries, relative researches on inhabitants of several temperate countries show a small percentage to harbour the E. hislolytica, some without complaint of dysenteric symptoms. The conditions of climate, sanitation, food and living may favourize individual resistance as well as susceptibility to acute symptoms. Recently a few workers in England have concluded that there are two or more strains of the E. histolytica, distinguishable by the size of the cyst each


 * These figures indicate the volume an

forms. French physicians in Indo-China have observed that in one region the E. histolytica gives rise to more severe dysentery and is less amenable to treatment than in another, thus raising the question of a difference in virulence amongst strains.

In Rumania in 1916 a new and distinct species of Bacillus dysenteriae Bacillus dys. Schmitz was first found.

In England and France the presence of bacteriophage has been determined. If a few drops of the filtrate from a culture of the dysentery bacillus Shiga be placed in a new growth of this bacillus, the micro-organisms are dissolved. The action is con- sidered due to the development of an ultra-microscopic micro- organism which destroys the bacillus and appears to be specific.

As dysentery may be due to diverse organisms, the causal one or its family or generic name is employed to specify the origin, thus amoebic, bacillary, spirochaetic, ciliar and helminthic dysentery. When there are evacuations of blood and mucus associated with inflammation and ulceration, not due to an organism which acts primarily and specifically on the lower bowel, but which may primarily attack another part of the body (e.g. tubercle, syphilis), or to carcinoma, or due to an impacted foreign body or mechanical irritation, the condition is termed, to distinguish it, pseudo-dysentery. When an ulcer is low down it can be seen and its character determined by the sigmoidoscope.

It is important to determine the causal organism in a sporadic dysentery case or in an epidemic, not only because of the specific treatment necessary but to assure adequate prevention of its extension; and laboratory collaboration for this is essential.

It has been amply exemplified that dysentery cannot be diag- nosed on the presence of blood and mucus in the stools with accompanying abdominal pain and tenesmus. One or more of these symptoms may be absent, for they depend on the extent or site of the ulceration. In the contact or healthy carrier of the E. hislolytica there may be no signs past or present, the E. histolytica to all appearances living as a harmless commensural within its human host, and the first sign of the presence of the disease may be a liver abscess, a very rare condition outside tropical regions. It is only by investigating these contact carriers in the laboratory that the disease can be detected from cysts in the faeces.

Dysentery has always been the most dire disease accompany- ing war. During the World War, despite our greater knowledge of its causes and of prophylactic measures to counteract it, its invaliding role was considerable in all armies, especially those fighting in tropical countries where the conditions favour it, and in parts of eastern Europe where sanitary control was not scrupulously exercised. The number of admissions to military hospitals which follow testify to its ravages amongst British troops, and many others there were who did not seek hospital treatment. The comparatively small death-roll was no doubt due to the application of the advances in our knowledge that dysentery may be due to diverse organisms, each having a specific line of treatment to be directed against it. Most deaths were due to Bacillus dys. Shiga.

In France there were n cases in 1914; 1915, 26 cases; 1916, 5,754; 1917, 6,031; 1918, 12,211 cases figures which are relatively small considering the number of troops there. In East Africa 1917, 9,369 cases, 317 deaths; 1918, 1,646 with 38 deaths. In Mesopotamia 1916 (6 months), 1,939 cases with 126 deaths; 1917, 4,860 with 151 deaths; 1918, 5,455 with 109 deaths. In Egypt 1916, 5,577 cases with 81 deaths. In Italy 1918, Forward Area, 897 cases with 17 deaths; Lines of Communication (Toranto), 146 cases. In Salonika 1916, 5,987 cases with 132 deaths; 1917, 5,842 with 124 deaths; 19181 9,318 with 158 deaths. On the Gallipoli Peninsula figures were not obtainable, but it is estimated that nearly every soldier who landed on the peninsula suffered from dysentery or diarrhoea and few escaped the former disease. Severe climate, difficulties of obtaining adequate food and sterilized water, fly pests, fatigue, hastily improvised resting places and sanitary arrangements, pro- longed periods in trenches all were important factors conducive to susceptibility in man and to the spread of infection.

Bacillary and amoebic dysenteries greatly predominated. There were exceptional and sporadic cases of spirochaetic and, amongst coloured troops especially, of ciliar and helminthic dysentery. In all countries bacillary greatly predominated. In France other than bacillary infections were rare and the amoebic type was found more frequently amongst those associated with troops from tropical countries or who took over camps or trenches used by them. In tropical and sub-tropical regions the percentage of amoebic to

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