While preventive measures are undoubtedly efficacious, in no class of diseases must the physician depend more entirely on the "vis physiologica vel medicatrix naturæ ;" that is, he should rely on a free supply of air, and other attentions to the normal functions such as are generally termed hygienic treatment, endeavouring, meanwhile, by nutriment to sustain life till the poison has been eliminated. Dr. Richardson of London has shown that in some of these diseased conditions, the breathing being normal, the patient sinks for the sole and simple reason that the blood will not take in the oxygen that is brought to it. In such cases the blood is charged with compounds which by their presence prevent oxygenation-precisely as antiseptics prevent that process out of the body. In typhus this is the common mode of death, and he terms it asphyxia commencing in the blood.

QUESTIONS FOR EXAMINATION.

JUNIOR.

1. What have been the two most remarkable theories as to the seat of diseases?

2. Enumerate a few causes which increase or decrease the redcells of the blood.

3. What results follow the increase or decrease of water in the blood respectively?

4. Are leucocythemia and hyperfibrinosis allied to each other? 5. What obvious pathological conditions accompany leucocythemia ?

6. In what cases has a deficiency of fibrin been found?

7. Is pyemia possible?

8. Enumerate the chief zymotic diseases, and explain their What chemical change of the blood do they interfere

nature. with?

9. What are the preventive and curative measures available in zymotic cases?

SENIOR.

1. Explain the action of remedies in cases of hyperemia.

2. Sketch the action of various causes in producing spanemia, and its symptoms.

3. By whom, and how, was leucocythemia discovered?

4. Mention some inflammations which do, and which do not, increase the fibrin in the blood.

5. State two theories of the cause of scurvy, and the facts and arguments which support them.

6. What are the proximate causes of cholemia?

7. Describe the condition of veins when blocked by thrombi. 8. Explain the diffusion of thrombi, and enumerate some consequent diseases

9. Sketch the analogies between zymosis and fermentation.

ABNORMAL NUTRITION.

UPON a careful review of all pathological processes, it will be found that there are very few of them which cannot be referred to a decrease, increase, or perversion of the function of nutrition. This will be evident from an examination of the following table, adapted from the great work of Dr. Williams with some slight modifications:

These conditions we proceed to sketch, referring for the many details of special diseases to treatises on medicine and surgery.

Atrophy implies a wasting of any part, the result of

decreased nutrition, or of interstitial absorption when it occurs faster than new material is laid down. It is not always abnormal, as such parts as the gubernaculum testis and thymus are removed in early life, and the mammary gland, spongy structure of the penis, and the testis are reduced when they have fulfilled their office. Its most frequent cause is disuse, thus the muscles and bones of paralysed limbs rapidly waste unless the artificial stimulus of electricity be substituted for the natural one of nervous force, which has been impaired or lost. A diminished quantity or inferior quality of blood will surely lead to atrophy of any part, as also will interference with the influence which we have seen the nervous system possesses over nutrition. The contraction of the calibre of arteries by increased action of their muscular coat is a frequent cause of atrophy, and the chronic gangrene which spurred rye produces may be explained in a similar way. Pressure, if constant, leads to atrophy; if occasional, to hypertrophy-which explains Hunter's remark, that pressure from within causes thinning; from without, thickening of parts. Atrophy may be general, marasmus; or partial, a condition from which no organ is intact. Atrophy is often combined with, or preceded by alteration in quality as well as quantity, as will be stated when discussing fatty degeneration. The curative indications clearly consist in securing a due supply of the nutriment of the wasted organ, and in promoting its activity by exercise.

Hypertrophy is the converse of the state we have just examined, and consists either in an increase in size of the materials which constitute a part, or an increase in their number. These two varieties Virchow distinguishes as simple and numerical. For the production of hypertrophy the following conditions are necessary: 1. Increased exercise of function; 2. Increased amount in the blood of the special materials of the part; and 3. Increased afflux of blood. Hypertrophy, unlike atrophy,

is never general; but, like it, it may be normal, as when an ordinary muscle augments in bulk; but if the muscle be the heart the alteration is fraught with danger, as we know it is usually the result of valvular disease, and the cause very frequently of sudden death by rupture of the cerebral vessels. Both these occurrences, as well as the hypertrophied or columnar bladder in urethral stricture, are the result of the first condition we have enumerated, Increase of adipose tissue, or obesity, is an example of the second circumstance, and the reader will find this subject discussed in my "Lectures on Public Health." No more forcible example of the action of the third condition could be adduced than the vast increase of the cock's spur when transplanted to the more vascular comb. In hypertrophy all the excess of blood is utilised or converted into tissue similar to that of the organ, but in inflammation it is wasted in the formation of new products. In double glands, or glands of similar office, the impairment of one leads to vicarious hypertrophy of the other. Virchow believes that nervous influence is not necessary in order that parts should take up an increased quantity of materials, for in parts "entirely destitute of nerves, as, for example, the surface of an articular cartilage, we can, as was shown many years ago by beautiful experiments of Redfern, produce altogether similar effects by means of direct stimuli."

REPAIR.

Although the reparative process cannot be regarded as in itself abnormal, it may be conveniently considered here, as it is an increased condition of nutrition, and it follows injury or disease. Mr. Paget explains that something similar occurs in inorganic matter; if, for example, a crystal of alum be broken, it will repair itself if placed in a solution of that salt. The process is more powerful in the humbler animals, as shown by experiments on the hydra, which can be divided into many pieces, all

of which repair the loss sustained, and become complete animals. Crustaceans also will even perform a voluntary amputation of one of their claws, when disturbed, and it is rapidly reproduced. In the human fœtus, spontaneously amputated limbs attempt reproduction; and White, in 1785, related that a supernumerary thumb was formed twice after removal.

We will consider cicatrization before treating of the inflammatory process, which, so far from being essential, was shown by Prof. Macartney of Trinity College, in his great work, to be always obstructive of the event. Paget enumerates five methods by which soft parts may unite: 1. Immediate union; 2. Primary adhesion; 3. Granulation; 4. Secondary adhesion, or the union of granulations; 5. Scabbing. Hunter believed that blood might form the bond of union, and in internal parts clots do occasionally become organized. 1. Immediate union was first shown by Macartney, and may follow if the wound be cleanly incised, be closed at once, and all blood pressed out. 2. The second method is more usual. The sides of the wound do not touch, but are united by lymph poured out, as some believe, by adhesive inflammation; this constitutes the cicatrix when organized, but it always remains different from the neighbouring cutis, not containing pigment, hair, or sebaceous glands, if the whole thickness was destroyed. The process may be completed in 48 hours, as we have seen in hare-lip, which is a good example of this method. Liston, it is well known, advised that the wound should be exposed till it "glazed;" but then it is very apt to unite in the next way. This is always a very desirable mode of union, save in a few cases-wounds of throat, those in lithotomy, and some other operations; or those made to evacuate a deep abscess, for examples, in which special circumstances compel us rather to keep open. 3. The formation of granulations is usually determined by the access of the oxygen of the air which excites suppuration.