German Sims Woodhead

“ The more organic matter present the greater is the virulence of water so contaminated; and the addition of such water to milk has, in one instance at least, led to an outbreak. If cholera dejecta be sprinkled on moist soil or damp linen, and kept at blood-heat, the bacillus multiplies at an enormous rate in the first twenty-four or thirty-six hours; but, as seen in the Dunbar-Schottehus method, at the end of three or four days it is gradually overcome by the other bacteria present, which, growing strongly and asserting themselves, cause it to die out. ”

“ By allowing the organism to grow in a well-aerated culture the virulence is gradually diminished, and this virulence, once abolished, does not return even when numerous successive cultures are made on agar or other nutrient media. On the other hand, by passing the cholera bacillus successively through the peritoneal cavities of a series of about thirty guinea-pigs, he obtains a virus of great activity ”

“ What evidence we have at our disposal, however, is all in favour of the transmissibility of the disease from patient to patient and through the agency of the leprosy bacillus. None of the numerous non-bacillary theories of leprosy account at all satisfactorily for this transmissibility of the disease, for its progressive nature, and for the peculiar series of histological changes that are met with in various parts and organs of the leprous body. Leprosy occurs in all climates. ”

“ In the streptococcal inflammations spreading by the lymph channels appears to be specially prevalent. In the blood the organisms, if in small numbers, are usually destroyed by the plasma, which has a powerful bactericidal action; should they escape, however, they are carried without multiplication into the capillaries of the general circulation, of the lung, or of the liver, where, being stopped, they may give rise to a second focus of infection, especially if at the point of impaction the vitality of the tissues is in any way lowered. ”

“ Once the organism, whatever it may be, finds its way into the system, it soon makes its presence felt, and toxic symptoms are developed. The temperature rises; the pulse, at first rapid, gradually slows down; and after some time persistent vomiting of bile comes on. At the end of three or four days the temperature and pulse fall, and there is a period during which the patient appears comparatively well; this is followed in a few hours by icterus and scanty secretion of urine. There may be actual anuria, or the small quantity of urine passed may be loaded with casts and albumen ”

“ One of the great difficulties met with in the earlier periods of the study of this organism was its slow, though persistent, growth. At first cultivations in fluid media were not kept sufficiently long under observation to allow of its growth; it was exceedingly difficult to obtain pure cultures, and then to keep them, and in impure cultures the tubercle bacilli were rapidly overgrown. Taken directly from the body, they do not grow on most of the ordinary media, and it was only when Koch used solidified blood-serum that he succeeded in obtaining pure cultures. ”

“ When the pneumococcus grows in chains—the second form—as when cultivated outside the body, on blood-serum or on agar over the surface of which a small quantity of sterile blood has been smeared, it produces very minute translucent colonies. Like Weichselbaum’s bacillus, it must be re cultivated every three or four days, otherwise it soon dies out. Unlike the other forms previously described, it may, when passed through animals, become extremely virulent, very small quantities being sufficient to kill a rabbit. ”

“ The fact, however, that the organism may remain alive in water is of great importance; and, as in the case of cholera, it must be recognized that certain of the great epidemics of typhoid or enteric fever have been the result of " water-borne infection." The bacillus, a facultative parasite, grows outside the body, with somewhat characteristic appearances and reactions: it flourishes specially well on a slightly acid medium ”

“ C . — Infective Diseases in which an Organism has been found, but has not finally been connected with the Disease.
Hydrophobia is usually contracted by man through inoculation of an abraded surface with the saliva of an animal affected with rabies — through the bite of a dog, the animal in which the so-called rabies of the streets occurs. The puppy is specially dangerous, as, although it may be suffering from rabies when the saliva contains an extremely exalted virus, the animal may exhibit no signs of the disease almost up to the time of its death. ”

“ In tetanus, as in diphtheria, the organisms producing the poison, Lf found in the body at all, are developed only at the seat of inoculation; they do not make their way into the surrounding tissues. In this we have an explanation of the fact that all the earlier experiments with the blood from tetanus patients gave absolutely negative results. It is sometimes stated that the production of tetanus toxin in a wound soon ceases, owing to the arrest of the development of the bacillus, even in cases that ultimately succumb to the disease. ”

“ As soon as the blood is driven out, leaving the nodule pale, make a puncture with the point of a sharp knife. From this puncture a clear fluid exudes; this, dried on a cover glass, stained with carbol-fuchsin, and rapidly decolonized with a weak mineral acid, shows bacilli stained red and very like tubercle bacilli; they differ from that organism, however, in that they are somewhat shorter, and that if the acid be too strong or be allowed to act on them for too long a time, the colour is discharged from them much more readily. ”

“ Although it has never been demonstrated that the filaria is directly inoculated into the human subject from the proboscis of the mosquito, it seems impossible to doubt that when the mosquito " strikes, " the filaria makes its way into the circulation directly from the proboscis. It is important to note that the mosquito, when fed on banana pulp, does not eject the filaria from its proboscis. This, however, is not to be wondered at, as the filaria is apparently unable to live on the juices of the banana; moreover, the consistence of the banana is very different from that of the human skin. ”

“ It may be readily understood that the trypanosome under these conditions soon loses its virulence, and an animal cannot be infected through the bite of the Glossina for more than 48 hours after the infected blood has been ingested by the fly. The organism may remain latent in the human body for a considerable period. It certainly sets up very tardily any changes by which its presence can be detected. The first symptoms of its presence and activity are enlargement of the lymphatic glands, especially those behind the neck, a condition often accompanied by irregular, and intermittent fever. ”

“ It is important to remember that this bacillus is a strict anaerobe, and can only grow when free oxygen has been removed from the cultivation medium. It may be cultivated in gelatine to which has been added from 2 to 3 % of grape-sugar, when, along the line of the stab culture, it forms a delicate growth, almost like a fir-tree, the tip of which never comes quite to the surface of the gelatine. The most luxuriant growth — evidenced by the longest branches — occurs in the depth of the gelatine away from free oxygen. ”

“ The first form, acute infective or epidemic cerebro-spinal meningitis, is usually associated with Weichselbaum's Diplococcus intracellularis meningitidis (two closely apposed disks) , which is found in the exudate, especially in the leukocytes, of the meninges of the brain and cord. It grows, as transparent colonies, on blood-agar at the temperature of the body, but dies out very rapidly unless reinoculated, and has little pathogenetic effect on any of the lower animals, though under certain conditions it has been found to produce meningitis when injected under the dura mater. ”

“ Its power of forming poisonous substances appears to vary directly with the amount and nature of the albumen present in the nutrient medium; and though it grows most readily in the presence of peptone, it appears to form the most virtilent poison when grown in some form or other of crude albumen to which there is not too free access of oxygen. From the experiments carried out by Koch, Nicati and Rietsch, and Madeod, there appears to be no doubt that the healthy stomach and intestine are not favourable breeding-grounds for the cholera bacillus. ”

“ Certain other diseases, such as cholera, give a similar specific serum reaction with their specific organisms. These sera have, in addition, a slight common action—a general agglutinating power—which, however, is not manifested except in concentrated solutions, the higher dilutions failing to give any clumping action at all, except with the specific bacillus associated with the disease from which the patient, from whom the serum is taken, is suffering. ”

“ As soon, however, as the warm weather comes round and the mosquito becomes active and again begins to bite there is evidence that it still maintains its power of transmitting infection; indeed Boyce states that mosquito's infected in one year are capable of transmitting infection and starting a fresh epidemic in the following warm season. When it is remembered that a mosquito by a single bite is capable of setting up an attack of the disease, we see how important is this question. ”

“ Other observers maintain that the amoebae may pass through the walls of the intestine, through the peritoneal cavity, and so on to the liver where they give rise to typical abscesses.
Syphilis. — It has long been recognized that syphilis is a specific infective disease, but although characterized by fever, anaemia, and increased growths of tissue followed by rapid degeneration and ulceration of tissue, it is only within quite recent years that a definite parasitic organism, present in all cases of typical syphilis, has been isolated and studied. ”

“ Diphtheria. — In regard to no disease has medical opinion undergone greater modification than it has in respect of diphtheria. Accurately applied, bacteriology has here gained one of its greatest triumphs. Not only have the aetiology and diagnosis of this disease been made clear, but knowledge acquired in connexion with the production of the disease has been apphed to a most successful method of treatment. In 1875 Klebs described a small bacillus with rounded ends, and with, here and there, small clear unstained spaces in its substance. ”

“ It is probable that most of the pigment found in the organs taken from malarial patients is derived from red blood corpuscles broken down by the malarial parasites; many of these, in turn, are devoured by leukocytes, which in malarial blood are usually greatly increased in number, and frequently contain much pigment, which they have obtained either directly from the fluid plasma or from the pigmented parasitic organism. ”

“ This organism, when taken from young broth cultures twelve to twenty-four hours old—during the period at which flagella are best seen—and examined microscopically, exhibits very lively movements. When, as pointed out by Gruber and Durham, blood-serum, in certain dilutions, from a case of typhoid fever is added to such a culture, the broth, at first turbid, owing to the suspended and moving microorganisms, gradually becomes clear, and a deposit is formed which is found to be made up of masses or clumps of typhoid bacilli which have lost their motility. ”

“ Tuberculosis. — In no quarter of the field of preventive medicine have more important results accrued from the discovery of a. specific infective organism than in the case of Koch's demonstration and separation in pure culture of the tubercle bacillus and the association of this bacillus with the transmission of tuberculosis. In connexion with diagnosis — both directly from observation of the organism in the sputum and urine of tuberculous patients, and indirectly through the tuberculin test, especially on animals — this discovery has been of very great importance ”

“ The bacillus is usually straight or slightly curved and rounded at one end; it appears to be non-motile. As first pointed out by Loeffler and Schiitz, when a portion of a culture is inoculated subcutaneously, typical farcy, with the acute septicaemia or blood-poisoning so characteristic of certain cases of glanders and farcy, is the result. The human subject is usually inoculated through wounds or scratches, or through the application of the nasal discharge of a slandered animal to the mucous membrane of the nose or mouth. ”

“ If a small fragment of tuberculous tissue be pounded in a sterile mortar and smeared over the surface of inspissated blood-serum solidified at a comparatively low temperature, and if evaporation be prevented, dry scaly growths make their appearance at the end of some fourteen days. If these be reinoculated through several generations, they ultimately assume a more saprophytic character, and will grow in broth containing 5% of glycerin, or on a peptone beef-agar to which a similar quantity of glycerin has been added. ”