T. Spencer Cobbold

“ In 1845 Dujardin placed the worm with the true distomes, yet, at the same time, expressed grave doubts as to whether it were, in any sense, a fluke. “Ce ver,” he remarks, “n’est certainement pas un distome ni même un trématode. Si sa forme extérieure et ses deux oscules lui donnent quelque ressemblance avec les distomes, sa structure musculeuse la rapproche davantage des Gordius, et son tégument ressemble à celui des siponcles.” ”

“ Even our metropolitan scientific institutions, expressly raised for the purpose of diffusing useful knowledge, shrink from the revelations of parasitism. Dominated by the miserable conception which judges that the life-history of a worm cannot prove either interesting or instructive to their audiences, they let slip the acquisition of scientific data, a knowledge of which might enable them to combat successfully some of the most terrible evils to which human flesh, in common with that of animals, is heir. ”

“ You are well aware that the establishment of the Royal Medical Society of Edinburgh was first brought about by the energy of a few enlightened individuals. "These youthful aspirants after truth perceived that it was not merely the frigid plodding over books, nor the doctrines and precepts of age and authority, nor the detail of empirical practice, that could inspire that taste and spirit, and give that manly tone to our inquiries which alone can render study agreeable, vigorous, and successful. ”

“ None of the internal parasites “continue in one stay;” all have a tendency to roam; migration is the soul of their prosperity; change of residence the essential of their existence; whilst a blockade in the interior soon terminates in degeneration and death. I repeat it. The entozoa constitute a specialised fauna. What our native country is to ourselves, the bodies of animals are to them. To attack, to invade, to infest, is their legitimate prerogative. ”

“ Do not be slothful because it is often argued that merit cannot always ensure a corresponding reward. The insufficiency of merit and of honest endeavours to the acquisition of fame and fortune, will doubtless give occasion to the discontented to repine and to censure the economy of human affairs; but they who are conversant in the investigation of final causes easily perceive that such a dispensation tends to perfect virtue by the exercise of patience. There are those who enter on the practice of our art totally destitute of preparatory instruction, and who make a merit of their defect. ”

“ As the parasites are apt to cause suffering to the bearer, a superstitious age sought to interpret their presence as having some connection with human wrong-doing. We can now afford to smile at such erroneous ideas. The intimate relation subsisting between parasitic forms dwelling in man and animals, and their interdependence upon one another, alone suffices to preclude the idea that parasites have been arbitrarily placed within the human bearer. It would seem, indeed, that our existence is essential to the welfare and propagation of certain species of parasites. ”

“ The facts of hydatid parasitism in animals, though often peculiar, are, for the most part, of an order similar to those presented in the human subject. If any medical practitioner thinks it beneath his dignity to study the pathology of the lower animals, the conduct of John Hunter in this respect is a standing protest against such narrowness.
The museum of the Royal College of Surgeons of England contains some of the finest specimens of hydatids from the lower animals that are to be seen anywhere, the very choicest of them having been selected by Hunter himself. ”

“ Even if we suppose that the Ascaris suilla and A. lumbricoides are not identical species, still it is evident that any person discharging the eggs of lumbricoids in the vicinity of open waters becomes, by that fact, a source and centre of infection. To ensure an endemic it is probably only further necessary that the human inhabitants should employ the contaminated water for domestic purposes. But time and an increase of temperature must be allowed for the bringing about of those known and unknown larval changes that alike form the necessary antecedents of infection. ”

“ The follicle-mites form a family by themselves (Demodicidæ) , and, as already observed, those infesting the dog and cat are, alike, mere varieties of the human species (Demodex folliculorum, var. caninus and var. cati) . Whilst the human parasite restricts itself to the face, the canine variety (fig. 52) will occupy any part of the dog’s body. The follicle-mite of the cat, however, usually confines itself to the ear. According to Mégnin, to whose beautiful monograph we owe so much, two or three dozen of these parasites may be found occupying a single follicle of the dog. ”

“ Let it be freely granted that to the practising physician, as such, it matters little how many beasts, birds, reptiles, or fishes perish annually from parasitic affections; yet, when it is demonstrable that a large proportion of the strictly human entozoa require a change of hosts—or, in other words, need to pass through the bodies of the lower animals—then it is evident that some acquaintance on his part with the entozoa infesting animals becomes a practical necessity. ”

“ Simonds, I am led to believe that the parasites are entirely new to science. The hood being well marked there can be no doubt as to the strongyloid affinities of the worm. I therefore propose to call the worm after its discoverer (Strongylus Axei) .
In regard to Sp. microstoma, the males measure up to 2/3′′, whilst the females have a long diameter of 3/4′′ or rather more (10′′′) . The small-mouthed maw-worm lives free in the stomach, and, as Krabbe observes, not unfrequently in very considerable numbers. It does not appear to be capable of injuring the host. ”

“ The tail of the male is spirally twisted, that of the female only slightly curved. Notwithstanding the many opportunities afforded of examining this parasite in the fresh state, very little is known respecting its origin and course of development. Dr Manson, who found that the mouth was armed with a five- or six-toothed oral saw, considers that the eye is not a proper resting place for the parasite, and that when one wandering worm comes across the track of another it follows it up from sexual instinct, and thus several may be found together in one place. ”

“ It must be obvious that in all cases where the intermediate host can be captured and destroyed, the life-cycle of the parasite can be broken and interrupted, and if thus broken, there is an end to the further propagation of the species. The knowledge that we have acquired by experimental research in this connection has already enabled us to set a limit upon the prevalence of certain well-known disorders, such as Trichinosis, Cestode-tuberculosis, and so forth. ”

“ As a student of parasites for some thirty years, I must without offence be permitted to protest against the too frequent omission of parasites in statistical evidence as a cause of mortality. From facts within my own knowledge I can confidently assert that parasites in general, and hydatids in particular, play a far more important part in the production of disease and death than is commonly supposed. ”

“ It is just these very persons who, when placed in high positions of social, political, or professional trust, most powerfully contribute to check a nation’s progress. There are too few genuine workers at science in this country. As one of the rank and file, I claim only to have honestly contributed my mite. I should like to see a small army of helminthologists rise up and lay siege to the fortresses at present securely held by thousands of death-dealing parasites. ”

“ Beef measles are extremely common in the cattle of the north-west provinces of India, so much so that severe restrictions have been imposed upon the consumption of ration beef. The presence of a few measles in the flesh of cattle has been deemed a sufficient excuse for condemning and burying entire carcases. The measle is easily distinguished from that of mutton and pork by the fact that its head is not furnished with hooks, whilst in the place of a rostellum there is a small, centrally placed, retractile disk, which assumes the appearance of a supplementary sucker as in the adult worm. ”

“ Below the anus the papillæ are regularly arranged in pairs, seven in number, the two uppermost pairs being double.
Notwithstanding the advantage which the size of this entozoon affords us in the matter of observation and experiment, we are yet ignorant as to the precise mode in which the young gain access to the human body. From what has been said respecting the quick growth of Ascaris mystax in the dog, and from what has been observed respecting the rapid growth of the so-called A. suilla in the hog, we know that the worm requires but a short time to pass from the larval to the sexual state. ”

“ The embryo is very broad in the body, and occupies all the interior space. An embryo such as Küchenmeister has represented under the form of a small filiform worm folded on itself, and only occupying a very small part of the cavity of the egg, is never to be seen. In the non-fecundated females, on the other hand, the uteri are filled with eggs, which, instead of the embryo, enclose a non-segmented yolk furnished with a large germinal vesicle. ”

“ Another point of special interest in connection with the parasites of insects concerns the development of Mermis albicans. At or near the time of the maturation of the ova, the parent worm, hitherto lodged within the body of some insect, buries itself in the soil. It commences its migration by boring its way out of the body of the host. Some difference of opinion exists as to the condition of the parent at the time of its wandering, for Von Siebold asserted that it quitted its parasitical mode of life “in order to become sexually mature away from the animal” infested ”

“ Dr Rowe, writing from the Goulburn district, said:—“The mere presence of flukes in the viscera of an animal is no proof that it is unfit for human food. For inspectors of slaughter-houses to adopt such a test of wholesome food would be the greatest mistake. It would afford no protection to the public against unhealthy food, would increase the price of animals, and be ruinous to our farmers and graziers. If the consumption of flukey beef and mutton were prejudicial to the health of man, there would be very few people alive in this part of the colony ”

“ Another species of thread-worm (Filaria lacrymalis) is occasionally found in the horse between the lids and eyeball. It is a comparatively small and harmless parasite, the males measuring 1/2′′ in length and the females 2/3′′. It also infests the ox. Both the large and small eye-worms are viviparous, and, not improbably, both of them are the means of conveying embryonic Filariæ into the circulation. Be this as it may, we owe to Dr Sonsino the discovery of hæmatozoa in an Egyptian horse. The larval worm was provisionally named by him Filaria sanguinis equi. ”

“ It would seem, in short, that the eggs of nematodes which normally take up their residence in cats, dogs, and in the carnivora which reside in arid regions, will develop embryos in the egg without external moisture. As before remarked, Davaine thinks it is not necessary that these nematode embryos should pass through any intermediary bearer, and he believes that they are often directly transferred to the stomach of their “hosts” whilst adhering in the form of an impalpable dust to the coats of their bearers, whence they are detached by the animal’s frequent habit of licking the fur. ”

“ As regards the injurious effects of this parasite upon man, it may be said to act prejudicially in three separate ways. I have remarked in my ‘Entozoa,’ that this parasite may cause disease and death both by its action in the larval and adult states. It may likewise injure us by rendering the flesh of swine unwholesome.
When one or more sexually-mature tapeworms have developed themselves within the human intestine, they are apt to give rise to a variety of unpleasant symptoms, more or less marked according to the habit or irritability of the patient. ”

“ The biologist may say what he lists, but he knows perfectly well that the superstitious mind will continue to ignore the precious and elevating results of scientific research, and that it will perseveringly continue to persuade itself that internal worms, parasites, and entozoa, of whatever kind, belong to the category of “plagues” liable to be distributed as special punishments for human wrong-doing.
As remarked in my previous treatise, the best way of studying the entozoa is to regard them as collectively forming a peculiar fauna, destined to occupy an equally peculiar territory. ”

“ One of the most remarkable equine parasites is that which I am in the habit of calling the large-mouthed maw-worm (Spiroptera megastoma) , in contra-distinction to the small-mouthed species (S. microstoma) . In this country the worm has attracted little notice, but through the kindness of Mr Spooner Hart, of Calcutta, and of Mr Percivall, of the 11th Hussars, stationed at Umballa, I have had abundant opportunities of examining this entozoon and the singular pathological appearances which it occasions. ”

“ Because Lewis found that canine hæmatozoa were digested, and thus perished in the stomach of mosquitoes, it had been argued that human hæmatozoa must necessarily undergo similar processes, and consequently die. Those who oppose the views of helminthologists in respect of the intermediary host-function of insects on such grounds can have very little general, and still less special knowledge of the phenomena of parasitism. It is the old story. When any new discovery is made, it must always pass through the ordeals of denial and doubt before it can be generally accepted as true ”