PART II.-REVIEWS AND EXTRACTS.

ARTICLE IV.

Researches upon the Blood. By M. DUMAS. (Translated for this Journal, from the August number of the Annales de Chimie et de Physique by JNo. M. B. HARDEN, M. D., of Liberty Co., Ga.)

The blood contains three nitrogenized organic principles which are essential to its nature and its functions, viz., fibrine, albumen, and the red globules. Their abundance in the blood or the importance of their offices has long drawn to them the special attention of chemists and physiologists.

But if it has been a very easy matter to separate the fibrine from the blood by the simple process of beating (battage) after obtaining it from the vein; or no less easy to procure the albumen by allowing its serum to separate by spontaneous coagulation; this is not the case when we wish to obtain the red globules free from all fibrine and albumen.

Recently, however, a peculiar process first pointed out by Berzelius, and afterwards more fully developed by M. Muller, has suggested to MM. Lecanu and Figuier* a method of obtaining the globules free from all mixture. This method is founded upon a modification which the blood undergoes, by its admixture with certain salts, in its transmissibility through the pores of our filtering paper. If we pour some blood, which has been beaten and deprived of fibrine and consequently fluid upon a filter made of joseph paper, we see the globules of this blood pass through the filter, and the filtered fluid will be of a deep red color. The filtration, which in such a case is slow and tedious, leaves upon the filter nothing but a residue of globules, altered in appearance and so small in quantity as to render it impossible to study their properties.

But if, before filtering the blood, we mix it with three or four times its volume of a saturated solution of sulphate of soda, this mixture will so modify the properties of the liquid in which the globules float that it passes through the pores of the paper, leaving behind all the globules upon the filter. It drains off completely colorless and altogether limpid, and as the process is generally rapid the globules may be collected in a satisfactory state of purity and integrity.

The application of this process, however, is not devoid entirely of some difficulties, which are worthy of attention, because of some circumstances connected with the nature and office of the red globules which they make manifest.

For example, if we take blood deprived of fibrine, but kept for many hours, and attempt to filter it after the addition of even an increased

*An interesting paper upon this subject, from the pen of M. Figuier, may be found in the 11th vol. of the Ann. de Chimie et de Phys., page 503.

quantity of sulphate of soda, the fluid passes with difficulty and is always colored.

It is necessary, therefore, that we operate upon blood recently drawn from the animal. As soon as it has been well beaten and all the fibrine is coagulated, we should pass it through a fine piece of linen and receive the fluid into a solution of the sulphate of soda. The mixture being now thrown upon a filter, we obtain a fluid perfectly limpid with a slightly yellowish tint, and all the globules will remain upon the filter.

But soon, however, the liquid which has been drained off being replaced by a fresh solution of the sulphate of soda for the purpose of washing the globules, we see it pass through colored, feebly at first, afterwards a little more so, and, at last, the color becomes so deep that we cannot doubt that the globules have been greatly altered in their properties.

Yet it is necessary, in order to obtain the globules pure, to wash them many times with the solution of the sulphate of soda-without which they will remain impregnated with the serum of the blood, that is to say, with an albuminous fluid whose presence will entirely conceal their true characters.

After a good many useless attempts, I have found in the globules of the blood a remarkable property by means of which this difficulty may be avoided.

As long as the globules of the blood are in contact with air or aera. ted water; as long as, in one word, they are in the arterial state the solution which contains them passes colorless through the filters and leaves them all behind.

But, on the contrary, as soon as these same globules have taken the violet color which characterizes venous blood, the filtered fluid becomes colored.

It is necessary, therefore, to maintain the globules in the arterial state during the continuance of the filtration and the washings. This I have been able to do in a satisfactory manner, by plunging into the filter a slender tube, by means of which I direct a constant and rapid current of air through the fluid.

Thus treated, the globules are deposited with some difficulty from the fluid, which is now maintained in a state of aeration favorable to the permanence of the arterial condition.

I throw, therefore, upon a large filter moistened beforehand with a solution of sulph. soda, the blood just after its passage out of the vein, but deprived of its fibrine, and diluted with a solution of sulph. of soda-a continual current of air passes through the liquid which is contained in the filter-a tube connected with a solution of the sulphate of soda supplies continually the loss of the fluid which is drained off.

By means of these precautions, the globules of the blood may be completely separated from the serum. Nevertheless, when we wish

the operation to succeed, it is necessary to neglect nothing that can ensure its rapid execution.

As soon as the globules have had time to be deposited upon the sides of the filter, and form there a layer of sensible thickness, those which are in contact with the surface of the paper cannot be longer acted upon by the air and pass immediately to the violet, whilst those which make up the exterior layer preserve the arterial state, and evidently arrest all the air contained in the washings.

In consequence of this the fluid passes colored, and if we do not immediately remedy this difficulty, its increasing coloration will soon demonstrate that the globules have undergone a great alteration.

Under these different circumstances the globules of the blood be. have as if they were truly living beings, capable of resisting the solvent action of the sulphate of soda, as long as their vitality continues, but yielding to the action as soon as they become asphyxiated, which results in this case from a deprivation of air, and which is manifested with singular rapidity, either by a change of color, or by their prompt solution.

Hence the object of the chemist must be to preserve the vitality of the globules, and among the means which present themselves to the mind we may mention the agitation of the fluid, its constant aeration, and lastly, the keeping of the blood at the same degree of temperature at which it was found in the body of the animal.

All these precautions being followed, we are furnished in a few hours with pure globules, provided we do not undertake to prepare more than five to six grammes at one time.

This rapid alteration of the globules, as soon as they are deprived of the direct contact of air, or of aerated water; the extreme energy with which, in a layer of globules, those which occupy the surface appropriate to themselves the whole of the oxygen, causing a fluid to pass to those below, which is entirely unfit to arterialize them, are circumstances well calculated to fix the attention of physiologists. In the discussions in which the respiration has been the object of our inquiries, the blood has always been regarded as a homogeneous fluid, receiving the contents of the air in the lungs, and undergoing there more or less rapid alterations.

Doubtless the serum of the blood does constitute such a fluid, nor will I dispute the part which it may take in the phenomenon of respiration; but the globules of the blood compose so many vesicles floating in this serum, having a respiration peculiar to themselves, whose effects, connected with those resulting from the respiration of the serum, produce by their ensemble the general phenomenon of the respiration of the blood.

We may say, therefore, laying aside for the present the proper action of the serum upon the air, that the respiration of one of the superior animals, and particularly of man, has for its object the contact of oxygen with the globules of the blood and the expulsion of the products into which they are converted.

Researches upon the Blood.

19

Hence, if we wish to calculate the effects of respiration, we must take into consideration the membranes which form the envelope of these globules, for we know how very different from a pure and simple solution of a gas are those strange phenomena of endosmose which take place through membranes which separate two reservoirs filled with different gases, or with fluids saturated with these gases.

Respiration, in order to be well understood, must therefore be studied in these vesicles or blood-globules, the principal seat of those phenomena which it is destined to produce, and whose organization complicates so strongly the physical laws which govern it.

The manner in which these blood-globules act upon the surrounding or dissolved air, and the conditions under which they preserve their normal character, become, when thus regarded, subjects of the highest interest.

To determine the integrity of the globules and the existence of their fundamental property, we have two means, both of which are equally exact, the microscope and the agitation of them with oxygen-as long as the globules are entire the microscope will indicate it: as long as they may be arterialized they will redden in contact with

oxygen.

Now every body knows that the blood possesses these two characters whilst it is circulating; nor does it lose them after its escape from the animal. The beating of the blood, by which the fibrine is separated, does not injure the globules nor deprive them in any way of the property of becoming arterialized.

In this phenomenon the albumen is no more needed than the fibrine. When we gradually replace the serum in which the globules are suspended, by a solution of sulphate of soda, they preserve no less their integrity, and they become no less reddened by being agitated with oxygen.

Thus the faculty of assuming the brilliant color of arterial blood belongs to the globules; it is independent of the albumen, of the serum, of the fibrine of the blood, and of the vital action of the animal.

But if the sulphate of soda preserves this property of the globules, will this be the case with all the alcaline salts? By no means-experiment proves this.

The common phosphate of soda which exists in the blood, may, like the sulphate, saturate the blood without in the least destroying in it the property of becoming arterialized. Blood saturated with phosphate of soda, when agitated with oxygen, receives a brighter arterial tint than it would have done without it.

In regard, therefore, to this property at least, the blood may without inconvenience have added to it much larger quantities of the sulphate or phosphate of soda than it naturally contains.

The salts formed from the organic acids, such as the salt of Seignette, are similar in their effects, which leads us to believe that the lactate of soda may exist in the blood, even in large proportion, without producing any ill effects in this respect.

But is this the case with common salt or chloride of potassium? Experiment shows that these salts are altogether different in their effects.

If we saturate blood deprived of fibrine, although fresh, with common salt, and agitate it immediately with oxygen gas, it remains of a sombre violet hue. Sal ammoniac produces the same effect.

Does there not exist an iutimate connection between these phenomena and the supposed injurious effects of salted meats in the production of scurvy? Must we not also find some agreement between the action of sal ammoniac, upon the blood, and the poisonous properties of this and other ammoniacal salts upon the body?

But however this may be, it is certain that there are some salts which leave the blood the property of becoming arterialized, whilst there are others which entirely destroy this property. The sulphate and phosphate of soda and the salt of Seignette belong to the first division; the chlorides of potassium, sodium, and ammonium to the second.

With these results, there is one circumstance connected which cannot fail to arrest our attention. Those salts which maintain in the blood the property of becoming arterialized, are at the same time the best adapted to preserve the integrity of the globules, and they give it the property of furnishing a colorless serum by filtration. On the contrary, those which take away this property cause the filtered serum to be more readily colored.

The whole of these experiments lead us to believe that the coloring matter of the blood is peculiarly fitted to take on the characteristic tint of arterial blood, when it is connected with the globules themselves, of which it forms a part. This character is modified, or lost, when by the alteration or destruction of the globules, the coloring matter enters truly into solution.

By comparing with great care specimens of the same blood, brought into contact with alcaline salts, and allowed to be saturated with these salts in the cold-it appears to me that generally these saline solutions, agitated with oxygen, act in the following manner:

Those salts containing complex organic acids, as the tartaric and citric, preserve the integrity of the globules much better than the salts formed from the mineral acids.

Those salts which have soda for a base, are better fitted to maintain this integrity than those with potash or ammonia as the base.

There appears, therefore, to exist an unexpected relationship between the integrity of the globules, the arterial state of the blood, the phenomena of respiration, and the nature or the proportion of salts dissolved in the blood.

It requires only a few experiments of this kind to be convinced that asphyxia may be induced in the midst of air, or of oxygen gas, with. out any apparent change in the phenomena of respiration, by the simple introduction into the blood of those salts which modify the action of the oxygen upon the red globules.