MISTRY. 



[GELATINE, 



or tissues, an formed from the substance* dissolved iu 

 the juice This mother-iuic*, at the same 



time, own* iU iuiuiixliato origin to the blood. 



$ 11. As the trauiudatiun of the blood is dependent on 

 iU 789-thousandths of water, all solid parts of our body 

 are, and most of them very abundantly, saturated with 

 thu liquid. But the water of the blood never pair 

 through the capillaries without salts. 



\ certain quantity of the inorganic constituents of the 

 blood is therefore to be found in all tissues. Some of 

 them are, however, remarkable for a very especial affinity 

 to certain tissues. Thus, in the bones, basic phosphate 

 of lime predominates not only above all other inorganic 

 uUUnccs, but also above all their other components. 

 The affinity of common salt to the cartilages is equally 

 .is. The muscles, on the other hand, contain 

 an equally large portion of chloride of potassium, the 

 quantity of common salt being but small. Thus, while 

 the blood contains much more common salt than chloride 

 of potassium, the muscles possess much more of the 

 latter than of the former. 



Fluoride of calcium is another inorganic constituent, 

 which, whilst contained in the blood only in a small 

 quantity, forms a necessary material for certain tissues. 

 Bones and teeth regularly attract this substance from t lie 

 blood. Herein, also, we may recognise one of those 

 peculiar affinities of tissues for certain inorganic sub- 

 stances of the blood, which are so frequently met with. 



Carbonate of lime, or chalk, which of itself is insoluble 

 in water, has not yet been discovered in the blood ; but 

 it is possible that it may pass as such through the cir- 

 culation into the bones ; for the carbonic acid and chloride 

 of potassium of the blood, have the power of keeping 

 small quantities of carbonate of lime in a dissolved state ; 

 and one part of the carbonate of lime is formed out of 

 the sulphate of lime, which reaches the blood with the 

 water and other nutriments wo take. This sulphate of 

 lime is decomposed by carbonate of soda, so as to form 

 .sulphate of soda and carbonate of lime. This new com- 

 pound is a characteristic constituent of the bones. 



12. With a small quantity of most of the inorganic 

 compounds in the juice of nutriment, a part also of the 

 albumen of the blood passes into all tissues. 



But certain laws of affinity prevail also amongst the 

 albuminous substances, which determine their appearance 

 in a regular way. Thus the crystalline lens of the eye 

 appropriates the globulino of the blood ; the walls of the 

 blood-vessels, caseine ; and the muscular tissue, fibrino. 



It is true the latter is not entirely identical with the 

 fibrino of the blood ; for it is not in the muscles in a dis- 

 solved state, but forms fibres, which are characteristic of 

 flesh. And yet this fibrine of the muscles is more easily 

 dissolved in water containing a few drops of hydrochloric 

 acid, than coagulated fibrine of the blood. 



I IP- influence of these laws of affinity is still more 

 extensive with regard to those tissues which contain 

 modified albuminous substances. To these belong horn, 

 gelatine, and the tvbttance of the fibrous tissues. 



Horn is composed of nitrogen, carbon, hydrogen, and 

 oxygon, in proportions altogether similar to those of the 

 albuminous substances. It covers the outward surfaces, 

 it lines the walls of all cavities of the body ; for the 

 epidermis, nails, hair, the coating of the mucous mem- 

 branes lining the cavities of the intestines, the windpipe, 

 month, and other interior parts of our body, consist of 

 horny substances. 



though these parts, so different externally, are all 

 called horny substances, on account of their affinity in 

 composition with the horns of cattle, they are l>y no 

 means identical ; for, apart from the differences of their 

 qualities, which certainly are not very considerable, they 

 contain certain quantities of sulphur, which clcn 

 beside* nitrogen, carbon, hydrogen, and oxygen, is to bo 

 i in all of them. The smallest quantity of sulphur 

 is contained in the epidermis, and the coating of the 

 mucous membranes; the nails contain more, the hair 

 most. The two latter are with very great difficulty 

 soluble in acetic acid. All horny substances agree with 

 each other, and with the albuminous substances, in i 



solubility in potash, from which solution they are prc- 



iUxl by acids. 



We ha vu to distinguish two kinds of gelatine : the one 

 is prepared from the cartilages, the other fnuu the bones. 

 Bone-gelatine is obtained by boiling bones in water. 

 A saturated hot solution, which has been thus prej 

 coagulates, when cooling, into a thick gelatine, which 

 swells by the addition of cold water, and is dissolved 

 again when boiled. In short, this substance is the well- 

 known glue, which plays such an important part in the 

 ordinary affairs of life ; it is the same substance, 1 

 known as jelly, into which veal broth coagulates in 

 cooling. But gelatine is not, as such, contained in the 

 bones ; it is produced by a slight transmutation, which 

 this organic basis of the bones undergoes in boiling. 

 Therefore bones are called a gelatine-yielding tissue, 

 which appellation is justly extended to many other com- 

 ponent parts of our body ; that is to say, to those fibres 

 which, accumulated in bundles, invest most in 

 of our body, and connect them with each other. For 

 the lost-mentioned property they are sometimes called 

 1 'imling tissues, though generally known as cellular. 

 The stratum of the skin beneath the epidermis, th> 

 terior covering of the lungs, intestines, muscles, nerves, 

 bones, and of many other organs, consist, for the greatest 

 part, of fibres, which, as well as the bones themselves, 

 yield gelatine when boiled. The bones furnish a clear 

 evidence of the affinity of the gelatinous tissues for 

 phosphate of lii 



Nitrogen, carbon, hydrogen, and oxygen, with a very 

 small quantity of sulphur, compose the bone-gelatine. 

 This is soluble in hot water; and has the important 

 property of not being precipitated from this solution by 

 acetic acid. 



Similarly to the bones, the cartilages yield, when 

 boiled for a length of time, a peculiar gelatine, called 

 gelatine of cartilage. This contains the same elein 

 as the bone-gelatine, only in other proportions. While 

 it agrees with the hitter in stiffening to a jelly when the 

 hot solution cools, it is the distinctive character of 

 gelatine of cartilage that strong acetic acid produces a 

 precipitation from a solution of it in water. We refer 

 DON again to the above-mentioned affinity of the tissue 

 yielding gelatine of cartilage with common salt. 



\\ liilst horn and gelatine possess au essential simi- 

 larity in their composition to the albuminous substances 

 of the blood, by containing sulphur, the clastic Ji 

 are without this ingredient. But the latter still contain 

 nitrogen, carbon, hydrogen, and oxygen, iu such a pro- 

 portion as to remind us directly of the albuminous sub- 

 cs in spite of this difference. Their absolute in- 

 solubility in water, as well as their resistance to acetic 

 acid anoi potash, prove, however, that with respect to 

 their properties they deviate the farthest from the albu- 

 minous substances. In these dissolving media they 



for days entirely uudissolved. 



Elastic fibres are found in an abundant quantity in 

 the ligaments, which unite together the different bones 

 of the spine ; besides being found in the lungs, the walls 

 of the arteries, and isolated in many other parts of the 

 body. 



That horn, gelatine, and the substance of the elastic 

 fibres, are justly to bo regarded as modified albuminous 

 substances, is proved by the fact, that, with the excep- 

 tion of a very small quantity of fat containing nitrogen 

 and phosphorus, no other compounds of nitrogen arc 

 present in the blood than the albuminous matters, which 

 ilso alone contain sulphur. Horny substances and gela- 

 :inc, both of which contain sulphur, can thus only have 

 :heir origin in the albuminous principles of the blood. 

 Perhaps it might be suggested, thai the fat of the blood, 

 which contains nitrogen, may produce the substance of 

 ;t-stic fibres; but the quantity of this fat is much 

 too small for the considerable quantity of clastic fibres 

 ,n our body to 1 from it. The conclusion that 



<ho albuminous compounds are tho only originating 

 source of thu horny sulwl. linn and the elastic 



ibres, is rendered unquestionable by the fact, that none 

 of these substances are found as such in the blood. 



