Collectanea de Diversis Rebus: Addresses and Papers

by Sir Peter Eade

With regard to vegetable parasitic growth I will not now detain you. The blights, and the mildews, and the ergots, as well as minuter forms, such as algæ and micrococci, are well known; and no doubt much more is still to be learned from their further investigation; whilst by analogy it seems highly probable that the circulating fluids of higher members of the vegetable kingdom may be found to be invaded by parasitic beings in the same way as their animal compeers.

But it is to Germ life in animal bodies that I wish now specially to allude. I have said that our knowledge in this direction has, even in the last two or three years, made enormous strides, and it is now almost a matter of certainty that all contagious or infectious disorders, as well as many others, are but the expression of the fact that minute living bodies have made a resting-place for themselves in or upon other living tissues; and that the development of the phenomena of these morbid states is but an indication of their presence and reproductive activity—either as cause, or as an accompaniment of these disease manifestations. And this applies not only to the human species, but to lower classes of animals, between whom and man many of these diseases are interchangeable.

Such knowledge necessarily invests the life history of these minute Germs with intense interest, seeing that it is probably one step, and that a long one, towards the discovery of the means of prevention, if not also of cure, of many of our most fatal and dreaded diseases.

Examples of such diseases are:—Scarlet Fever, Diphtheria, Small Pox, Cholera, Yellow Fever, Tuberculous Disease, Ague, Hydrophobia, Cattle Plague, Anthrax; and many others might be enumerated whose dependence upon parasitic Germs is almost conclusively proved. But these are sufficient to show the deep interest of this branch of study.

Not only are these Germs found in the solids of the body in some of these diseases, but in others their presence is easily and constantly recognisable in the blood or other fluids, and even within the corpuscles which the blood so largely contains. And not only so, but the forms which these micro-organisms present are so constant and so definite in the different disorders, that it is now almost possible in some instances to diagnose what diseased condition we have to deal with by an examination of the fluid or tissue in which they are contained.

It is, perhaps, but right here to say that some of our most cautious observers consider that it is as yet hardly proven that the differing Germs found in the various diseases are their actual and efficient cause; but their definiteness in the various disorders, and the constancy of their presence, leave little doubt that this will hereafter be conclusively shown to be the case.

Some of these Germs seem to have a short life and rapid development, and then we have acute disease. Others seem to have a more prolonged or continuing career, and then we have chronic disease. Whilst others seem to have an intermitting development, and then we have paroxysmal disease.

Many curious facts have been observed in reference to the forms, or multiplication, or life-history of some of these parasitic beings. Thus, for example, in one class (Filaria sanguinis) it was noticed that the minute embryos of this little blood-worm could only be discovered in the evening or during the night, and not during the day; and the reason of this has appeared to be that it is necessary that they should come within reach of the Mosquito Gnat, which is a night-feeding animal, in whose bodies one stage of their development appears to take place.

One of the latest discoveries in this department of natural history is that of the blood germs, which co-exist with the various forms of ague and malarious disease, and upon which they would appear to depend. Dr. Osler, of Pennsylvania (now Regius Professor of Medicine, at Oxford), has recently described and figured these little bodies in an elaborate paper full of interest.

Such facts as these, when regarded merely from the point of view of a member of the Medical Profession have their deep and special significance. But I am here to-night as a member of the Naturalists’ Society, and by all of us, in that capacity, they are first to be regarded, not as illustrations of disease, but of the life history of some of nature’s creations—creations which are no doubt as important, as definite, and which play as large a part in the general scheme of life, as do many of the larger forms of animated beings.