/y. FLESH FOODS A PRACTICAL HAND-BOOK SELECT WORKS for ANALYSTS, ENGINEERS, & OTHERS DAIRY CHEMISTRY FOR DAIRY MANAGERS, CHEMISTS and ^alysts A Practical Handbook for Dairy Chemists and others having control of Dairies. With Tables and Illustrations. By H. Deoop Richmond, F.C.S., Chemist to the Aylesbury Dairy Company. 16s. “ The BEST CONTRIBUTION on the subject that has yet appeared.”— iancet. THE PRINCIPLES AND PRACTICE OF BREWING. A Text- Book for the use of Students and Practical Men. By Walter J. Sykes M.D. D.P.H. F.I.C., Editor of the Analy)t. With Plates and numerous Illustrations. ’2I8. A better guide could hardly be found.”— Counti/ Brewer^ Gazette. TECHNICAL MYCOLOGY. A Practical Handbook on Fermentation for Brewers, Distillers, Analysts, Technical and Agricultural Chemists. By Dr Franz lAFAR, Professor of Fermentation-Physiology and Bacteriology in the Technical High School, Vienna. VoL. I., Complete in itself. With numerous Illustrations. Price 15s. The chapters TEEM WITH INTERESTING MATTER from beginning to end.”— TAe Lancet. FOODS : Their Composition and Analysis. By A. WYNTER BLYTH, M.R.C.S., F.C.S., Barrister-at-Law, Analyst for the County of Devon, and Medical Officer of Health for St Marylebone. With Elaborate Tables, folding Litho. Plate and Photo- graphic Frontispiece. Fourth Edition. Revised and Enlaiged. 21s. “Simply INDISPENSABLE in the analyst’s laboratory.’* — Laiwet. POISONS : Their Effects and Detection. By A. WYNTER BLYTH, M.R.C.S.,F.C.S. Third Edition. Large Svo, cloth, with Tables and Illustrations. 21s. “Undoubtedly THE MOST COMPLETE WORK on Toxicology in our language."— Anafi/gt. OILS, FATS, WAXES, and the Manufacture therefrom of Soaps, Candles, and other Products. By C. R. ALDER WRIGHT, D.Sc., F.R.S. With 144 Illustrations. Handsome cloth. 28s. “ Will be found absolutely indispensable by every chemist.”— TA« Analyst. LUBRICANTS AND LUBRICATION. The Theory and Practice of Lubrication, and the Nature, Properties, and Testing of Lubricants. By Leonard Archbutt, F.I.C., F.C.S., and R. Mountford Deeley, M.I.M.E., F.Q.S. With Tables, Illustrations, etc. 21s. “A most valuable addition to technical literature.” — Railway Official Gazette. PAINTERS’ COLOURS, OILS, AND VARNISHES. A Practical Manual. By GEORGE H. HURST, F.C.S., Member of the Society of Chemical Industry. With valuable recipes and numerous Illustrations. 12s. 6d. “ The ONLY English Work that satisfactorily treats of the Manufacture of Oils, Colours, and Pigments." — Chemical Trade Journal. PETROLEUM AND ITS PRODUCTS. A Practical Treatise. By BOVERTOK REDWOOD, F.R.3.E., F.I.C., Assoc.Inst.C.E., Consulting Adviser to the Corporation of London under the Petroleum Acts, etc., etc. In Two Volumes. Large 8vo. With numerous Maps, Plates, and Illustrations in the Text. 45s. “The MOST COMPREHENSIVE ACCOUNT that has yet appeared of a gigantic industry.”- Time*. GAS MANUFACTURE (The Chemistry of). A Handbook on the Production, Purification, and Testing of Illuminating Gas, and the Assay of the Bye- Proilucts of Gas JIanufacture. By W. J. ATKINSON BUITERFIELD, M.A., F.I.C., F.C.S. Second Edition, Revised and Enlarged, with New Section on Acetylene. Numerous Illustrations. 10s. 6d. “The BEST WORK of its kind which we have ever had the pleasure of reviewing.”— Voumaf of Gas Lighting. CALCAREOUS CEMENTS: Their Nature, Preparation, and Uses, with some Observations on Cement Testing. By GILBERT R. REDGRAVE, Assoc.Inst. C.E., etc. In large crown 8vo. Handsome cloth. With Diagrams. 8s. 6d. “Will be useful to all interested in the MANUFACTURE, USE, and TESTING of Cements."— Engineer. London : CHARLES GRIFFIN & CO., Ltd., E.xkter St., Strand. EBER’S COLOUR SCALE for the Estimation of HYDROGEN SULPHIDE liberated from FLESH. m Uigqsg T'l FLESH FOODS WITH METHODS FOR THEIR CHEMICAL, MICROSCOPICAL, AND BACTERIOLOGICAL EXAMINATION A Practical Hand-Book for Medical Men, Analysts, Inspectors, and others BY C. AINSWOETH MITCHELL, B.A.(Oxon.), F.I.C., F.C.S. WITH ILLUSTEATIONS AND A COLOUEED PLATE LONDON CHARLES GRIFFIN & COMPANY, LIMITED EXETER STREET, STRAND 1900 \_All Bights Reserved.'] PREFACE. The word ‘flesh,’ like so many other words in the English language, has come to have a very extended application, and although in its strictest sense it is applied to the muscular tissue only, yet it is often used to connote the combined mus- cular and connective tissue (including fat and bone), or even the whole of the interior organs and tissues of an animal. It is with flesh in the sense of muscular fibre that this book chiefly deals, although the connective tissue and blood are touched upon as being intimately associated with the muscle. It has been the author’s endeavour to collect and summarise in a convenient form, records of investigations which are, for the most part, scattered throughout English and foreign scientific books and periodicals, and to select such methods as appeared most suitable for the examination of meat and its preparations. In describing these methods an elementary knowledge of analytical chemistry and bacteriology on the part of the reader has been assumed, so as to save the space which would have been required for details which may be found in any general text-book. The author gratefully acknowledges the valuable assistance given him by many friends in the preparation of this book, and especially by Mr. Otto Hehner, and by Dr. Sykes, editor of the Anahjst, to whom he is also indebted for the loan of numerous preparations of the parasites of flesh. viu PREFACE. ’ He would also express his best thanks to Mrs. E. Mitchell and Mr. R. M. Prideaux, F.I.C., for their kindness in drawing many of the dlustrations; to Dr. Kdnig for permission to make use of the numerous tables published in his classical work, Cliemie der -menschhchen Nahrungs- und Genussmittd ; and to Dr. H. Schjeming for the communication of the results of unpublished work. 57 Chanceky Lane, London, W.C., May 1900, C. A. M. CONTENTS. CHAPTER I. STEUCTUEE AND CHEMICAL COMPOSITION OF MDSCULAE FIBEE. Structure of Muscle. — Non-striated Muscle — Striated Muscle — Pale and Bed Muscles— Muscle Plasma. Proteid Constituents.— The Sarcolemma- Proteids of Muscle Plasma — Nucleins — Phospho-Carnic Acid — Enzymes —Colouring Matters— Stroma Substance. Nitrogenous Non-proteid Con- stituents.— Meat Extractives — Neurinic Leucomaines — Kreatinic Bases — Xanthic Bases — Leucomaines of the Fatty Acid Series — Amido Acids. Non-nitrogenous Organic Constituents. — Reaction of Muscle — Free Acids — Glycogen — Fat — Glucose — Inosite — Scyllite. Inorganic Con- stituents.— Mineral Matter — Water — Gases. Summary of the Com- position of Muscular Fibre, .... pp- 1-22 CHAPTER II. STEUCTUEE AND COMPOSITION OF CONNECTIVE TISSUE AND BLOOD. Conuective Tissue. — White Fibres — Elastic Fibres. Adipose Tissue. — Dis- tribution of Fat in the Body — Composition of Animal Fat. Cartilage. —Structure — Composition. Osseous Tissue.— Structure— Composition — Table of Mineral Constituents of Bone. The Blood. — Quantity in the Body — General Characteristics — Conditions affecting its Coagulation — The Red Corpuscles — Oxyhtemoglobin Crystals — Hsemin Crystals — Spectra of Heemoglobin and its Compounds — The White Corpuscles — The Blood Plasma — Proteids of the Plasma — Inorganic Constituents of the Plasma — Gases in Blood — Ultimate Composition of Blood — Proximate Composition of Blood — Identification of Blood in Stains, etc. — The Blood of Invertebrate Animals — Hsemolymph, . . pp. 23-45 X CONTENTS. CHAPTER III. THE FLESH OF DIFFEEENT ANIMALS. Flesh of Domestic Animals. -Beef-Veal-Mutton-Composition of the Flesh and Fat— ‘Braxy’ Mutton— Pork— Composition of Pig’s Fat- Horse Flesh— Horse Fat. The Flesh of Wild Animals and Birds.— General Characteristics— Bear’s Flesh— Composition of the Fat of Wild Animals and Birds—' Ripening ’ and ‘ Heating ’ of Game. The Flesh of Vertebrate Fish,— General Characteristics — The Fat of Fish— Con- stants of Certain Fish Oils. The Flesh of Invertebrate Animals. Composition of Representative Examples — Green Oysters, . pp. 46-69 CHAPTER IV. THE EXAMINATION OF FLESH. Colour. Abnormal Colorations — Artificial Coloration. Unsound Flesh. Chemical Tests— Eber’s Hydrogen Sulphide Test— The Reaction towards Litmus — Eber’s Test for Putrefaction. Treatment of Meat with Anti- septics. Blown Meat. Consistency of Flesh. — Determination of the Degree of Toughness. Odour of Flesh. Analytical Methods.— Deter- mination of Water — Ash — Sulphur — Chlorine — Soluble Extract and Muscular Fibre — Phospho-Camic Acid — Amide Nitrogen — Fat — Digesti- bility of Different Kinds of Flesh— Calculation of the Food Value — Scheme for the Examination of Fresh Meat, . . pp. 70-90 CHAPTER V. METHODS OF EXAMINING ANIMAT. FAT, Crystallisation — Specific Gravity — Melting and Solidifying Points — Iodine Value — Saponification Value — Hehner Value — Reichert Value — Acetyl Value — Acid Value — Separation of Liquid and Solid Fatty Acids — Determination of Stearic Acid — Oleic Acid — Linolic Acid — Linolcnic Acid, ....... pp. 91-101 CHAPTER VI. THE PRESERVATION OF FLESH AND THE COMPOSITION AND EXAMINATION OF PRESERVED FLESH PRODUCTS. The Decomposition of Flesh. Preservation by Cold. — Alterations in Frozen Flesh — Detection of Frozen Meat. Preservation by Drying. — Pemmican — Charque — Flesh Powder. Preservation by Salting. — Jlethods of Salt- CONTENTS. ■ XI ing— Addition of Nitre— Influence of Salting on the Flesh— Caviai. Preservation by Smoking.-Metliods of Smoking-Action of Smoke on Bacteria— Influence on the Flesh— Composition of Bacon. Heat bten- lisation and Exclusion of Air.— Canned Meats— Sardines— Methods of Examining Canned Meats — Metallic Contamination - Potted Meats. Preservation by Antiseptics.— Boric Acid— Sulphites— Salicylic Acid Formaldehyde, CHAPTER VII. THE COMPOSITION AND ANALYSIS OF SAUSAGES. German Sausages-English Sausages -French Sausages— Water in Sausages The Specific Gravity — Determination of Flour or Starch— Acidity Acid Value of the Fat — Determination of Gristle — Detection of Horse- flesh—Artificial Coloration— Action of Certain Dyes on Flesh Proteids— Action of Nitre on Natural Colouring Matters in Flesh— Methods of Extracting Artificial Colours, . . • • PP- 125-146 CHAPTER VIII. THE PROTEIDS OF FLESH. Definition and Classification of Proteids.— Composition of Representative Proteids — Albuminous Substances — Compound Albuminous Substances — Albuminoid Substances — Albumoses — Peptones — Combinations of Pro- teids with Hydrochloric Acid — Colour Reactions of Proteids — Heat Coagulation— Optical Rotation. Precipitation of Proteids.— By Alcohol —By ‘ Salting out ’—By Metallic Salts— Relation to the Periodic Law- Precipitation by Halogens — Scbjerning’s Method. Action of Formalde- hyde on Proteids. Decomposition of Proteids. —By Sulphuric Acid— By Superheated Steam— By Proteolytic Enzymes— By Bacteria, pp. 147-185 CHAPTER IX. MEAT EXTRACTS AND FLESH PEPTONES. Manufacture of Meat Extracts. — Physiological Value. Fluid Beef and Pep- tones.— Prepared by the action of Superheated Steam — By Pepsin — By Trypsin — By Papayotin — Physiological Value of Fluid Beef and Pep- tones. Analysis and Composition of Meat Extracts and Commercial Peptones. — Stutzer’s Method — Use of Formaldehyde in the Analysis of Peptones— Analyses by Alcohol Precipitation— Schjerning’s Method, pp. 186-206 Xll CONTENTS. CHAPTER X. THE COOKING OF FLESH. Advantages of Cooking— Amount of Loss— Composition of Cooked Meat- Composition of Cooked Fish-Eifect of Cooking on Animal Parasites- Thermal Death Points of Bacteria— Action of Heat on Bacterial Toxines Temperatures reached in the ordinary Processes of Cooking— Public Sterilisation of Infected Flesh in Germany, . . pp, 207-215 CHAPTER XI. POISONOUS FLESH. Flesh rendered Poisonous by the Food of the Animal-Poisons elaborated in the Cells of the Living Animal— Leucomaines also known as Ptomaines— Poisonous Fish— Poisons produced by Bacteria in the Living Animal— Mussel Poisoning— Poisons produced by the Action of Bacteria on the Dead Flesh — Summary of the Principal Ptomaines — Symptoms of Ptomaine Poisoning — Botulism or Sausage Poisoning, . pp. 216-226 CHAPTER XII. THE ANIMAL PAEASITES OF FLESH. Classification ofEntozoa. Sporozoa.-Miescher’s Tubes— Coccidia. T»niad». —Cystic Taiieworms— Cysticerci in Beef and Pork- Cccnurus Cerebralis — Tienia Echinococcus. Bothriocephalida.- B. Latus— Temperatures at which Cysticerci perish — Influence of Putrefaction on Cysticerci- Examination of Flesh for Cysticerci. Trematoda or Liver Flukes. The Trichina. --Life History— Number of Trichime in Infected Flesh Detection of Trichime— Parasites which might be mistaken for Trichinm —The Temperature at which Trichime perish— The Destruction of Trichinre in Flesh — Effect of Salting and Smoking — Occurrence of Trichime and Trichinosis, . , . . . pp. 227-264 CHAPTER XIII. THE BACTEEIOLOGICAL EXAMINATION OF FLESH. Bacteriological Methods — Embedding and Staining — Determination of the Number and Species of Micro-organisms— Bacteria of Normal Flesh— Chromogenic Bacteria— Phosphorescent Flesh— Bacteria of Putrefaction and their Products — The Bacillus of Sausage Poisoning. Pathogenic CONTENTS. xm Bacteria. — Pycemia — Septicmmia — Swine Fever— Hog Cholera Fowl Cholera Swine Erysipelas — Malignant (Edema — Tetanus Rabies Glanders Anthrax — Quarter Evil — Foot-and-Mouth Disease Tuber- culosis — Actinomycosis — Bothriomycosis — The Muscle Ray- Fungus Pathogenic Bacteria in Shell-fish, . . • • PP* 265-297 CHAPTER XIV. THE EXTRACTION AND SEPARATION OF PTOMAINES. Brieger’s Method of Extraction— Pouchet’s Method— The Stas-Gautier Method — DragendorfPs Method — Systematic Description of Ptomaines. Monamines. Diamines. — Putrescine — Cadaverine — Neuridine Saprine. Triamines and Tetramines of the Fatty Acid Series. — Guanidines. Aromatic Ptomaines not containing Oxygen. Monamines. — Pyridine-— Corindine. Aromatic Diamines and Triamines.— Morrhuine. Aromatic Tetramines, — Aselline — Scombrine. Ptomaines containing Oxygen or Sulphur.— Neurine — Choline — Muscarine — Betaine — Mydatoxine — Gadinene — Mydaleine — Tyrosamines — Mydine — Tirotoxine — Araido Acids — Carbopyridic Acids, ...» PP- 298-322 Index, . . pp. 323-336 LIST OF ILLUSTRATIONS. no.’ 1. Isolated Smooth Muscle, • . . , . 2 2. Strands of Smooth Muscle from Bladder of Frog, ... 2 3. Cardiac Muscular Fibre, • . . , , 2 4. Striped Muscle of Frog, 3 5. Striped Muscle of Calf, Teased, • 3 6. Muscular Fibre of Great Adductor of Rabbit, ... 3 7. Fat Cells from Rabbit, ...... 24 8. Fat Cells showing Nucleus, ...... 24 9. Transverse Section of Shaft of Human Femur, . . .30 10. Cancellated Bone, ...... 30 11. Human Red and White Blood-Corpuscles, . . . .34 12. Haemoglobin Crystals from Blood, ..... 35 13. Fleischl’s Haemometer, ...... 36 14. Hsemin Crystals, . . . . . . . 38 15. Spectra of Haemoglobin and its Compounds, . . .39 16. White Corpuscles under different Reagents, . . .40 17. Apparatus for the Determination of Stearic Acid, . . . ' 100 18. Apparatus for collecting Gases from Cans, . . . .115 18flt. Halliburton’s Apparatus for separating Proteids by Heat Coagulation, 162 19. Preparation of Muscle containing Miescher’s Tubes, . . 228 20. A Single Miescher’s 'Tube, ...... 228 21. Coccidia in the Liver of a Rabbit, ..... 229 22. Tania saginata (Natural Size), ..... 232 23. Head of Cysticerci of T. saginata, ..... 233 24. ‘ Measles ’ in Beef, ....... 233 25. Section of Free Proglottis of T. solium, .... 234 26. Portion of Section of T. solium, ..... 235 27. Section of Proglottis of T. solium, with Sexual Organs, . . 235 28. ‘Measles’ in Pork, ....... 236 29. Swine Cysticercus, ....... 237 30. Egg of T. solium, ....... 237 31. Head, etc., of T. solium and T. saginata, .... 237 32. Cysticerci of T. solium, ...... 238 LIST OF ILLUSTRATIONS. XV yio. 33. Cysticercus of T. solium, ....•• ^38 34. Head of Cysticercus jyisiformis, . . . • • 240 35. Ccenurus ccrehralis, ...•••• 36. Cysticercus fasciolaris, ...••• 241 37. Echinococcus Bladder, ....•• 243 38. T. echinococcus, 243 39. Head of B. latus, ...•••• 40. Ovum of B. latus, 245 41. Ciliated Embryo of B. lattis, . . . • • 245 42. Higher Larva of B. laius, ...••• 246 43. Higher Larva of B. latus, encapsuled, .... 246 44. Common Liver Fluke, ....•• 251 45. Immature female Trichina, ....•• 253 46. Encysted Tricldnse in Human Flesh, .... 255 47. Calcified Muscle Trichinae, ...■■• 255 48. Calcified Muscle Trichinae, ...... 256 49. Dead, Calcified Trichinae, ...... 256 50. Dead, Calcified and Disintegrated Trichinae, . ■ • 256 51. Fischoeder’s Compressor, ...... 258 52. Muscle Ray-Fungus, ...... 259 53. Calcareous Deposit in Muscle, ..... 260 64. Crystalline Deposit in Smoked Ham, .... 261 55. Muscle Distomum, ....... 261 66. Bacteria (after Baumgarten), ..... 266 57. Ranvier’s Microtome, ...... 267 58. Swift’s Freezing Microtome, ..... 268 ••S'-:. t 1 FLESH FOODS. CHAPTER I. STETJCTUEE AND CHEMICAL COMPOSITION OF MUSCTJLAE TISSUE. STRUCTURE OF MUSCLE. CLASSIFICATION OF MUSCULAR FIBRES. Flesh, in its primary sense of musculo/r contTdctile tissue, con- sists of numbers of fibres lying side by side, and united by means of connective tissue carrying the nerves and blood-vessels. These muscular fibres may be classified into three groups in accordance with their appearance under the microscope. 1. Unstriated involuntary muscle of the alimentary canal, blood-vessels, intestines, bladder, etc. 2. Striated involuntary muscles of the heart. 3. Striated voluntary muscles. 1. Non-Striated Muscle. — The unstriated or smooth muscular fibres, which are not under the control of the will, are composed of a number of small fibre cells, which are usually spindle-shaped and contain an elongated nucleus, the ends of which are surrounded by granular protoplasm. Although usually described as unstriped muscle, a longitudinal striation may frequently be observed in the fibres, especially after they have heen treated with reagents. 2. Cardiac Muscle. — This occupies an intermediate position, as regards structure, between the non-striated and striated muscle. It consists of elongated and branched cells, each of which contains a nucleus, and is marked by faint longitudinal and rough trans- verse striations. 3. Voluntary Striated Muscle. — The transversely striped muscular fibres, which, from the fact that they compose the 2 FLESH FOODS. muscular tissue under the control of the will, are often de- scribed as voluntary muscles, consist of long contractile fibres about -fj^inch in diameter, and as much as an inch or more in length. Fig. 1. — Isolated smooth muscle, X 300. {Stirling.) Fig. 2. — Strands of smooth muscle from Bladder of Frog, Each fibre is surrounded by an elastic envelope or sarcolemma, which is a structureless proteid body. On breaking a fibre in two, the ends of the sarcolemma may often be left attached to the two Fig. 3. — Cardiac muscular fibre. A, muscular fibres from tbe heart of a mammal, and C, from a frog ; B, transverse section of the cardiac fibres ; b, connective tissue corpuscles ; c, capillaries. {Landois and Stirling. ) fragments. The fibres, with their surrounding sarcolemma, are bound together by a variety of connective tissue, in \vhich lies a deposit of fat. From the interior of the fibre a viscous liquid CLASSIFICATION OF MUSCULAR FIBRES. O which readily congeals to a soft jelly can be expressed. This is known as muscle plasma. Fig. 4.— Striped muscle of Frog. A, sarcolemma raised ; B and C, ruptured fibres ; D, fibre treated with acetic acid ; E, muscle discs. {Stirling.) Fig. 5. — Part of striped muscle of Calf, teased, showing isolated bundles of fibrils. x 200. {Stirling.) Fig. 6. — Muscular fibre of great adductor of Rabbit, living and extended, a, dim disc ; 6, light disc ; c, intermediate or Dobie’s line ; n, nucleus seen in profile. Examined in its own juice, x 300. {Stirling.) Voluntary muscle shows but little vertical striation, but has characteristic transverse markings composed of alternating dark 4 FLESH FOODS, and bright lines. ^^Hien examined under higher powers of the microscope, the lighter stripe shows a further division, a thin black line, known as Krause’s membrane, making its appearance. In the darker stripes a region less dark than the rest may also be observed. This is known as Hensen’s disc. Striated muscle, after being steeped in alcohol or chromic acid, can be resolved into fibrillee, in each of which alternately light and dark transverse markings are visible. Horizontal cleavage can be brought about by macerating the fibres in dilute hydrochloric acid, which creates a tendency to split across through the bright bands, into a number of discs termed discs of Bowman. The numberless small particles which would be produced by a simul- taneous vertical and horizontal cleavage were called by Bowman * sarcous elements — a term which is now used iu a different sense. Sub-division of Voluntary Mtbscle. — The voluntary muscles of some animals show distinct differences in appearance, some being 2mle and others red. In the pale muscles, an example of which is seen in the breast muscles of a hen, the striations are well marked, and the longitudinal markings very faint ; in the red muscles the vertical striations are much more plainly visible. The red muscles contract more slowly than the pale muscles, the fibres are thinner, and they contain more sarcoplasm. Double Refraction of Muscle. — The property of double refraction is a characteristic of muscular fibre, and is readily demonstrated by means of the polariscope. It is especially marked in the case of striated fibre, though also clearly discernible in the smooth variety. Muscle Plasma. — When dead muscular fibre is examined, all the contents of the sarcolemma are solid ; but by rapidly freezing living muscular fibre and applying pressure, it is possible to express a viscous liquid which readily congeals to a soft jelly. This is known as muscle plasma, and it is the coagulation of this plasma which caiises the rigidity of muscular tissue, or rigor mortis, which rapidly sets in after death. The coagulation is retarded by cold, but only in the case of cold-blooded animals is it possible to thus delay it sufficiently to enable the plasma to be collected. According to Kiihne the contents of the sarcolemma consist of sarcous elements suspended in this liquid, and the changes which these bodies undergo in their form cause the con- traction of the muscle. * Phil. Trans. Roy. Soc., 1840, p. 457. PEOTEID CONSTITUENTS OF MUSCLE. 5 CHEMICAL COMPOSITION OF MUSCLE; COMPOUNDS. I. ORGANIC A.— PKOTEID CONSTITUENTS. The Sarcolemma.— This is composed of a proteid substance which is somewhat related to that of elastic tissue, from which, however, it differs in being slowly dissolved by acids and alkalies, and in being more readily acted upon by peptic and pancreatic Muscle Plasma. — Preparation. — Kiihne’s method of preparing this is to free the muscular tissue of a frog from blood by injection of a solution of salt (0‘5 per cent.) into the aorta, and to treat the fibre cut into small fragments, at 0° C., with more of the salt solution to eliminate the lymph. The fragments are then ^ozen by exposure to a temperature of - 7° C., cut into slices with chilled knives, pounded in a cold mortar, and pressed in linen at the ordinary temperature. The expressed liquid, which has a tem- perature of about 0“ C., is filtered through paper moistened with ice-cold salt solution. Proteids of Muscle Plasma. — Neumeister* gives a description of these, of which the following is a summary : — .ao n Myogen fibrin. — On warming muscle-plasma to about 40 O. coagulation takes place— a proteid substance, named myogen fibrin by Furth.t being deposited. The amount of this varies in different animals, a larger quantity being obtained from frogs’ muscle, for instance, than from that of mammals. Myosin.— On dialysing the plasma, from which the myogen fibrin has been removed, for twelve to twenty-four hours, in running water, and subsequently in distilled water, a, voluminous precipitate is obtained. This proteid, termed myosin by Furth, can also be precipitated by adding ammonium sulphate until the solution contains 23 per cent. It is of a globulin character. Myosin fibrin. — When a neutral aqueous solution of myosin, con- taining salt, is allowed to stand, it gradually becomes turbid and deposits a flocculent precipitate — myosin fibrin. This is insoluble in neutral liquids, and is regarded as an insoluble modification of myosin. It is completely precipitated from neutral solutions of myosin at 50° C. Myogen. — Myosin composes only about 20 per cent, of the proteids of plasma (rabbits’), the remaining 80 per cent, consisting of a proteid not precipitated by dialysis — myogen. It can be * Phys. Chem., p. 401. t Arch. Exper. Path. u. Pharm., 1S95, 36, p. 231, etc. 6 FLESH FOODS. isolated by complete saturation of the muscle plasma with ammonium sulphate after the myosin has been removed by partial saturation. It is not a globulin. On adding acetic acid or mineral acids to solutions of myogen, and then neutralizing, syntonin is precipitated. Soluble myogen fibrin appears to be an intermediate stage in the formation of myogen fibrin. Neumeister gives the following genetic scheme of the pro- duction of muscle fibrins from the plasma, and considers that some such change probably takes place in the alteration which occurs in muscle after death ; — Myosin. Myogen. . I . I- Myosin fibrin. ' Soluble myogen fibrin. I Myogen fibrin. Myoproteid. — Fiirth has isolated from the muscle-plasma of fish a proteid substance which he terms myoproteid. Nucleins. — These are not present in great quantity in muscular fibre. In dogs’ muscle they amount to about 0'37 per cent. The muscles of embryos, the composition of which is more akin to that of young cells, contain more. They are compound albuminous substances in which phosphoric acid is a principal constituent, in combination, in certain cases, with bases such as guanine, xanthine, etc. Neumeister gives the elementary composition of nuclein obtained from the yolk of egg as: — Carbon, 42T1; hydrogen, 6‘08 ; nitrogen, 14’73; oxygen, 31 '05; sulphur, 0‘55 ; phosphorus, 5T9; and iron, 0‘29 per cent. N ucleins are usually insoluble in water and alcohol, but dissolve in dilute alkalies. On treatment with boiling acids or alkalies they yield derivatives of the proteid part of the molecule together with phosphoric acid, and, in certain cases, nuclein bases and their derivatives. Phospho-Carnic Acid. — Siegfried precipitated with ferric chloride from muscle extract previously freed from albumin, a compound containing phosphorus, to which he gave the name of phospho- carnic acid, and which he considered was expended during muscular activity. It can be salted out with ammonium sulphate, and, on dialysis into water, decomposes, yielding phosphoric acid. Enz3rmes of Muscle. — The enzymes pepsin, ptyalin, and maltase have been identified in muscle. It is also probable that other enzymes are present, and the coagulation of the proteids of the plasma, and the acidity of the muscle after death, may possibly be brought about through the agency of bodies of this nature. niteogenous non-peoteid constituents. Colouring Matter of Muscle.— The colouriiK^ matter of the red muscles is hsemoglobin, was the first to practically demonstrate as ^^3 muscular tissue washed cornpletely ree muscles in mentioned before,! there is a difference in different parts of the same animal, and Ranvier I and Town that the red colour is a product of muscles Thus, muscles which are continually contracting, those of the heart, are of a deep red colour whilst ^hose whm are in a comparative state of rest are paler. In the breast muscles used in flying are dark ’'f > the case of the common hen, these are but rarely ejrcised Even in the muscles of the same animal, an increase of colour often accompknies an increase of strength- witness ^he Jifferen^ in the colour of the flesh of the calf and cow. According to Ranvier the muscle hemoglobin is not derived from the muscle substance, but originates in the blood-vessels. Colouring Matter of Fish Muscle.— In the muscular tissue of many kinds of fish {e.g. salmon and goldfish), there to hemoglobin, a peculiar rosy red colouring matter, which Krukenberg and Wagner § have found, in the case of the salmon, to be of the nature of a red lipochrome, and not a proteid substance. Myohxmatin.—Thm is one of a number of pigments {Insto- hsematins) discovered by MacMunnH in the muscles of many kinds of animals, and notably in the cardiac muscles of the _ pigeon. Though giving characteristic spectra they have never been isolate . Myohlematin appears to be capable of forming compounds analogous to'^the oxyhmmoglobin and methmmoglobin d.erived from hsemo- globin. MacMunn’s theory is that these pigments retain the oxygen which the blood brings to the tissue, until it is required ^Stroma Substance. — This is a simple proteid substance, which cannot be extracted from the sarcoplasmic bodies by neutral reagents. On treatment with dilute potassium hydroxide solution it passes into solution as an albuminate. B.— NITROGENOUS NON-PROTEID CONSTITUENTS. Meat Extractives. — When muscular fibre is extracted with boiling water, a considerable proportion of the proteid substances coagulate, and there pass into solution various non-proteid nitro- genous substances, together with other organic bodies and inorganic salts. The nitrogenous bases, to which Gautier gave the name of * Vireh. Arch., 1865, 33, p. 79. %Zdt. Biol., 1885, 3, 37-40. t P. 4. + Arch. Phys., 1874. 11 Phil. Trans. Roy. Soc., 1886, Pt. I. 8 PLESH FOODS. leucomaines or physiological alkaloids, are formed normally in the living cell at the expense of the lecithins or of other nitrogenous compounds (see page 217). Glassification of iLeuconiaines. — Gautier classifies the leuco- maines into five groups : — I. Neurinio Leucomaines, including choline, neurine, and betaine. II. Kreatinic bases, including kreatine, kreatinine, cruso- kreatinine, etc. III. Xanthic bases, including adenine, xanthine, sarcine, etc. IV. Leucomaines of the Fatty Acid Series, e.g. neuridine, cadaverine, gerontine. V. Amido-acids. I. Neurimc Leucomaines. — As a rule these bases are only found in small quantities in animals. They also occur as ptomaines in the products of the putrefaction of animal matter {cf. page 218). In both cases they appear to be derivatives of lecithins. Choline [C5HjgN02] has been found in small quantity in blood, in glands, and in the yolk of egg. A^ezinraerCjHjjNO] generally accompanies choline in traces. Betaine [CsHjgNOg] occurs as a normal constituent in certain molluscs, such as the mussel. II. Kreatinic Bases. — The general characteristics of these bases are that they are usually only slightly soluble in water, and nearly insoluble in alcohol. All are precipitated on adding zinc chloride to solutions of their hydrochlorides. All give precipitates with silver nitrate, and most of them with mercuric chloride. They are distinguished from the xanthic bases by containing more hydrogen, and by not being precipitated by copper acetate. Kreatine [(l4HgNg02] (or Methyl-glycocyamine) — ^h^.cooh is a feeble base discovered by Chevreul in 1835 in meat broth. It crystallizes in colourless needles and in rhombs which melt at 100° C. It is very soluble in boiling water, less soluble in alcohol, and insoluble in ether. When an acidihed solution of kreatine is boiled it is completely converted into its anhydride, kreatinine. ^(^H)<^N(CH3).CH2.C00H "" + ^2^- KREATININE. 9 When boiled with barium hydroxide it is hydrated, and yields urea and sarcosine. C4H9N3O2 + HgO = C0(NH2)2 + (NH).CH8.CH2.C00H. Gautier considers that this reaction explains the disappearance of the flesh bases from the tissues. Kreatine is precipitated by sodium phosphomolybdate, aiia by zinc chloride in the presence of hydrochloric acid and alcohol. Its hydrochloride [C,H9N302.HC1] crystallizes in prisms which are non-deliquescent, and but little soluble in alcohol. It gives no precipitate with Bouchardat’s reagent (I + KI), and no blue coloration with a mixture of ferric chloride and potassium ferricyanide. Method of Separation. — Kreatine can be isolated from an aqueous extract of meat by boiling, Altering, adding a slight excess of basic lead acetate, or of barium hydroxide, filtering, removing the excess of lead by hydrogen sulphide, or of barium by carbon dioxide, filtering, concentrating the liquid at a low temperature, and puri- fying, by recrystallization, the fine needles which gradually deposit. Kreatine has a slightly bitter taste. It is not very poisonous when injected into animals, but can be transformed by bacteria into the poisonous ptomaine, methyl-guanidine (page 307). It is a common constituent of the muscles of most animals, the avei’age amount found by C. Voit* being 0'21 to 0-28 per cent. He ob- tained the following quantities from the muscular fibre of various animals; — Frog, 0'21 to 0'35j fox, 0'206 to 0*237 3 ox, 0*219 to 0-276 ; dog, 0-223 to 0-248 ; rabbit, 0-269 to 0-336 ; and man, 0-282 to 0*301 per cent. There appears to be less kreatine present in cardiac muscles than in the voluntary muscles. Ki’eatinine [C^H^NgO]. — This base is invariably present in small quantities in the muscles of the higher animals. In certain fish {e.g. conger) Krukenberg found as much as 0*3 per cent. In cer- tain diseases, such as pneumonia and typhoid fever, the amount obtainable from the urine is largely increased.! Kreatinine forms brilliant prismatic crystals which are readily soluble in cold water (12 parts) and in alcohol (120 parts). In aqueous solution it gradually undergoes hydration, being converted into kreatine ; and the same result is obtained by treating it with dilute alkalies. It is precipitated by sodium phosphomolybdate from acid solu- tions, and by picric acid when the solution is not too dilute. Zinc * Zeit. Biol., 1868, iv. p. 77. + G. S. Johnson has shown that the kreatinine obtained from urine is not identical with the flesh-kreatinine. Proc. Boy. Soc. , xlii. p. 365. 10 FLESH FOODS. chloride precipitates it in crystalline needles [(C4H-N80)2ZnC1.2], which are nearly insoluble in cold water, and insoluble in alcohol. It gives a precipitate with mercuric chloride, but not with Bouchardat’s reagent (I + KI), or with Selmi’s reagent {Fe,C\, + K,¥e{CN),). It is converted by oxidizing agents into methyl-guanidine, and when heated with barium hydroxide in excess yields methyl- hydantoin. Weyl’s Reaction for Kreatinine. — On adding to a cold solution of kreatinine several drops of a dilute solution of sodium nitro- prusside, and then a little dilute sodium hydroxide solution, a red coloration is obtained which changes to yellow, and on acidifying the liquid with acetic acid and w'arming becomes green and then blue. This reaction is also given by substances allied to kreatinine which contain the group [CHg.CO] united to two atoms of nitrogen. Kreatinine has a. greater physiological effect than kreatine. Iso-Kreatinine. — J, E. Thesen * has isolated this base from the muscle of the haddock. It differs from kreatinine in its colour (yellow crystals), in its solubility in various solvents, reducing action on cupric compounds, and in yielding ammonia instead of methyl- guanidine on oxidation with potassium permanganate. It appears to be converted into kreatinine when allowed to stand in contact with milk of lime. Xantho-Kreatinine [CjH^qN^O]. — This base was discovered by Gautier t in 1882 in muscle and in meat extract. It has often been mistiiken for kreatinine, which it resembles in many respects. It crystallizes in yellow spangles, and has a slightly bitter taste, and an odour recalling acetamide. It dissolves in hot concentrated alcohol, and is fairly soluble in cold water. On heating it gives off ammonia and methylamine. Its reaction is amphoteric. Its hydrochloride crystallizes in feathery masses. The platino- chloride is very soluble. Zinc chloride gives a yellowish-white precipitate, consisting of groups of needles. Silver nitrate gives a gelatinous precipitate, and mercuric chloride a yellowdsh-white precipitate. No precipitates are given by potassium mercury iodide, cupric acetate, or iodine in potassium iodide. Xantho-kreatinine is poisonous w'hen injected in fairly large quantity, causing extreme lassitude, defecation, and vomiting. * Zeit. pJiys. Chem., 1897, 24, pp. 1-17. t Led Toxines, 1896, p. 236. XANTHIC BASES. 11 Cruso-Kreatinine [CgHigN.O]. -Gautier discovered this base in muscle in association with xantho-kreatinine. It crystallizes in orange-coloured lamellae, which are slightly alkaline and rather bitter. j t 4. fri-ip nnm The hydrochloride is soluble and non-dehquescent. The auro- chloride is crystalline and granular, W difficulty. The base is precipitated by ordinary alum, but not by zinc acetate. It is also precipitated by zinc chloride and inercuric chloride, and in acid solution gives a yellow precipitate with sodium phosphomolybdate. . t-. t It is not precipitated by potassium mercury iodide,_ by ciipric acetate, or by iodine in potassium iodide, nor does it give belmi s Prussian-blue reaction. _ , Gautier gives the following formula representing its constitution compared with that of kreatinine : / NH - CO NH:C< \N(CH3)-CH2 Kreatinine. /NH.C(NH)"-CO NH : C< I \ N(CHg) - CHg Cruso-kreatinine. Amphi- Kreatinine [CgH^gNi^Oj. — This is less soluble than cruso-kreatinine or xantho-kreatinine, which it usually accom- panies. . , It crystallizes from boiling water in oblique, yellow prisms, it has a slightly bitter taste and weak basic properties. When heated to 100° C. it decrepitates and becomes white and opaque. The hydrochloride is crystalline and non-deliquescent. The auro- chloride is trimorphic and very soluble. The base is not precipitated by copper acetate or mercuric chloride. It resembles kreatinine in its physiological characters. Bases and The first of these was found by Gautier in the mother-liquid from which the xantho- kreatinine had been crystallized, and the second in the mother- liquid of cruso-kreatinine. They resemble kreatinine in their properties. III. Xantbic Bases. — These bases have both basic and acid properties. They contain the group [C ; NH], and when heated with alkalies most of their nitrogen is converted into hydrocyanic acid. As a rule they are not directly hydrated by dilute acids or alkalies with the formation of urea. They are very stable, and can, in many cases, be transformed into one another. Tests for Xanthic Bases. — Most of the xanthic bases, when evaporated with strong nitric acid, leave a residue, which, on 12 FLESH FOODS. treatment with an alkali, turns orange, red, rose-colour, or brownish-yellow. This distinguishes them from the kreatinic bases. When mixed with chlorine water containing a trace of nitric acid and evaporated to dryness, a residue is obtained, which becomes orange-red or blood-red on the addition of ammonium hydroxide, and with sodium hydroxide often changes to blue. These leucomaines are also known as ‘ nuclein bases,’ from the fact that some of them have been found in the nucleins. Adenine [C5H5N5].— This base was discovered in 1885 by Kossel, who extracted it from vegetable tissues and from the glandular tissues of young animals (aS^v = gland), where it was invariably accompanied by guanine. Although not found in the aqueous extract of muscle, it may be suitably described here. Method of Extraction.* — The finely divided pancreas is extracted with water acidulated with sulphuric acid, the sulphuric acid removed from the extract by precipitation with barium, and the filtrate concentrated to about a tenth of its volume in vacuo at 50° to 60° C. The liquid is rendered alkaline wuth ammonia, treated with ammoniacal silver nitrate, and the resulting precipi- tate washed by decantation and drained on a porous tile. It is then dissolved in ammonium hydroxide (sp. gr. I'l) containing a little urea. On filtering and cooling, the adenine silver-salt crystallizes out, together with some guanine and hypoxanthine. The precipitate is washed, decomposed, under pressure, with hydrogen sulphide, the liquid filtered and concentrated, and the residue treated with ammonia in not too great excess. As the ammonia evaporates, adenine and guanine are precipitated, while sarcine remains in solution. The precipitate is taken up with warm hydrochloric acid, and on standing, guanine hydrochloride crystallizes out first. On concentrating the filtrate, the adenine hydrochloride is gradually deposited. Adenine can also be separated from sarcine by converting both into nitrates and concentrating the solutions, when sarcine is deposited as the free base while adenine nitrate (which is not decomposed by eA'aporation) remains in solution. Adenine crystallizes in transparent hexagons, which are soluble in 1086 parts of water, and more soluble in alcohol and glacial acetic acid. When heated with potassium hydroxide, it gives hydrocyanic acid. When evaporated with nitric acid it does not give an orange coloration on adding sodium hydroxide to the residue. The hydrochloride is crystalline and dissolves in 42 parts of water. The mercuro-chloride [(C5H5N5)2.HgCl2] is a fine grey powder which is insoluble in hot dilute hydrochloric acid. The * Gautier, Les Toxines, p. 250. XANTHIC BASES. hs"’rri' ;s5S » cy^dL With copper sulphate it yields an amorphous grey pre- cfpitate, which dissdves in dilute acids and alkalies aiui chloride produces a red coloration which does '' heating the solution. When adenine sulphate is heated on the water bath with sodium nitrite it is transformed into sarcme. Gautier gives the following constitutional formula for this base . NH— C.NH C ]S^_C.NH C : NH According to Guareschi it passes through the body into the urine '"“AtoT-Sarcine [CsHsN^.CsH^N.O].— This compound is obtained as a starch-like mass when hot solutions of adenine and sarcme are mixed in molecular proportions and allowed to cool, and can be crystallized in needles from an ammoniacal solution. | he com- pound hydrochloride is more soluble than the hydrochloride of either of the constituents. i , tt Guanine [C5H5N5O].— This base was discovered by Unger m 1844 in guano, whence it derives its name. It usually occurs only in very small quantity in muscular tissue and in various glands. Kossel extracted 0-005 per cent, from beef and still less from dogs flesh. In the muscle of embryos, however, and m the flesh of certain lower animals, such as the cuttlefish, it has been found 111 larger proportion. i • 4. j It is a white amorphous powder, sparingly soluble in water, and readily soluble in acids, but insoluble in alcohol and ammonium hydroxide. ^ - The hydrochloride [CgHgNjO.HCl-t-HoO] crystallizes^ in fine needles, which lose their water of crystallization at 100 C. and their hydrochloric acid at 200 C. The platiuo-chloride forms orange crystals, which are sparingly soluble in water. The sulphate forms long yellow needles, which are decomposed by water. Mercuric chloride forms an insoluble precipitate with it [(C6H5N50.HCl)2.HgCl2-l-H20], and potassium ferrocyanide pre- cipitates it in crystalline needles. Nitrous acid converts it into xanthine C.HsN^O -1- HN02=N2 4- H2O 4- C5H,N,02. 14 FLESH FOODS. When guanine is evaporated with nitric acid, then mixed with a little potassium hydroxide and evaporated to dryness, it gives the indigo coloration which xanthine gives under the same conditions. Guanine is not poisonous. In its passage through the system it is partly decomposed, with the formation of urea and uric acid. Pseudo-Xanthine [C^H^NgO], — Gautier discovered this base in muscle in association with kreatinine, sarcine, xantho-kreatinine, and cruso-kreatinine. Method of Separation. — It is isolated from meat extract by pre- cipitating part of the bases with 95 per cent, alcohol, evaporating the alcoholic filtrate, and taking up the residue with strong alcohol. From this solution various leucomaines are precipitated by ether. The mother-liquid of these, when boiled with copper acetate, gives a precipitate, which is decomposed with hydrogen sulphide. The liquid is filtered boiling, and the crystals, which are deposited on cooling, are dissolved in hydrochloric acid,* a crystalline hydro- chloride of the same form as that of sarcine being produced. The free base resembles xanthine in its physical and chemical properties. It is soluble in alkaline liquids. On evaporating it with nitric acid, and taking up the residue in water, an orange coloration is obtained. Silver nitrate precipitates it as a gelatinous salt, but no pre- cipitate is obtained with lead acetate. Its mercuro-chloride is very soluble in hydrochloric acid. Sarcine or Hypoxanthine [CsH^N^O].— This was first discovered by Scherer in the spleen, and afterwards by Strecker in muscle. The amount usually present in voluntary muscle varies from 0 07 to 0T2 per cent. It accompanies adenine and guanine in the tissues of many glands, and has been found in the blood of certain fish. Gautier suggests that in the organism it may be derived in part from guanine, which gives, on oxidation, sarcine, xanthine, and uric acid. Method of Se^mration. — It can be isolated from meat extract in the following manner : — After the nitrates of adenine and hypoxanthine have been obtained (c/. page 12) their solution is nearly neutralized, and a slight excess of picric acid added. Adenine picrate separates as a flocciilent yellow precipitate, while hypoxanthine picrate remains in solution. On adding silver nitmte to the boiling filtrate, the compound C5H3AgN40.CgH2(N02)g is obtained. This is decomposed with hydrochloric acid, and the picric acid extracted with ether. The hydrochloride of hypoxanthine is left in solution, and on the addition of sodium carbonate, the base is precipitated. * Les Toxines, p. 260. XANTHINE. 15 Sarcine is a white crystalline powder, more soluble than xanthine in boiling water, in which it forms a neutral solution. It dissolves in alkalies, and sublimes at 150“ C. without decomposing. Its hydrochloride (C5H4N4O.HCI + H2O) crystallizes in prisms. Its mercuro-chloride forms a flocculent precipitate which dissolves in acids. i u j x It is precipitated from acid solutions as a phosphomoly bdate, but is not precipitated by picrates. When oxidized with nitric acid it does not yield xanthine (Gautier), though the latter base is produced with permanganate as the oxidizing agent. Pure sarcine does not give the murexide test. It has a marked physiological action. When 50 to 100 milligrammes were injected into a frog, tetanic convulsions were produced after six to twenty hours. In a chicken it increased the secretion of uric acid (Gautier). Xanthine [C5H4N4O2].— This base, which almost always accom- panies sarcine and adenine, especially in glandular tissue, was discovered by Marcet in a urinary calculus in 1823. The quantity present in muscular fibre varies considerably. In the flesh of pigeons and hens, Kossel found from O'Ol to O’l per cent. Method of Separation. — Gautier gives the following method of separating it from an extract of the flesh. The extract is dissolved in as little hot water as possible, and precipitated with an excess of 95 per cent, alcohol. The residue is dissolved in water and treated with lead acetate (not in excess). The liquid is filtered hot, freed from lead, and concentrated by evaporation. Kreatinine crystallizes out first and is filtered off. On adding ammoniacal lead subacetate (not in excess) to the mother liquid, xanthine is precipitated, while hypoxan thine remains in solution. The lead compound is decomposed with hydrogen sulphide, and the boiling liquid filtered. Mercuric acetate is added to the fil- trate and the liquid boiled. The precipitate is decomposed with hydrogen sulphide, and the liquid again filtered while hot. On evaporating the filtrate, the xanthine separates out as a yellowish crust. It can be obtained synthetically by heating hydrocyanic acid with water and a slight excess of acetic acid at 145° C. 1 IHCN -f 4H2O = CjH^N^O 4- + 3NHg. Xanthine is soluble in 14,000 parts of cold and 1160 parts of boiling water. It is insoluble in alcohol and ether. It is de- composed at 156° C. with the formation of ammonium cyanide, carbon dioxide, formic acid, and glycocoll. Under the influence of nascent hydrogen it is converted into sarcine. Its hydrochloride [CgH^N^Og.HCl] crystallizes in needles and 16 FLESH FOODS. hexagonal plates. The platino - chloride forms soluble yellow prisms. The Muvexide Test. — On treating xanthine with a little nitric acid and evaporating the liquid to dryness, a yellow residue is obtained, which, on the addition of potassium hydroxide, becomes red, and changes to violet-blue on heating. When xanthine is treated with a mixture of a solution of an alkaline hypochlorite and sodium hydroxide, an olive to dark green colour is produced, which subsequently changes to brown and disappears. This test distinguishes xanthine from sarcine. Physiologically xanthine resembles sarcine. When injected into a frog it causes muscular contractions and paralysis of the spinal chord. Heteroxanthine [CgHaN^Og] (or Methyl-xanthine).— This base is foimd in small quantity in dogs’ urine, and possibly occurs in the flesh. It can be separated from paraxanthine by means of ammonia water, in which it is readily soluble. Paraxant^e [C^HgN^Og] (or Di-methyl-xanthine) was found by Salmon in 1883 in normal human urine. It is isomeric with theobromine. Carnine [C^Hgl^^Og]. — This base wasdiscovered in 1871 by Weidel in American meat extract, but was not found in the muscular tissue itself. It has since been found in normal urine by Pouchet, and in the muscular tissue of fish by Krukenberg and Wagner. Method of Separation. — It can be isolated by the following method : — The extract of meat is dissolved in water, treated with barium hydroxide (not in excess), and filtered. The filtrate is precipitated with lead subacetate, and the precipitate taken up with boiling water, which dissolves the combination of carnine and lead oxide. The lead is removed from the filtrate, the liquid filtered boiling, and silver nitrate added to it after concentration and cooling. The silver carnine compound is digested with an excess of ammonia, which dissolves the silver chloride simultane- ously precipitated. The silver is removed from the residue with hydrogen sulphide, the filtrate evaporated and decolorized with animal charcoal, and the carnine obtained by crystallization. Gamine is a white crystalline base with a neutral reaction and bitter taste. It is hardly soluble in cold water, and is insoluble in alcohol and ether, but is easily soluble in hot W'ater. On treatment with bromine water or nitric acid it is converted into hypoxanthine. CjHgN^Oa -f 2Br = CgH^N^O.HBr + CHgBr + CO^. It is distinguished from xanthine, hypoxanthine, and guanine in yielding with basic lead acetate a precipitate which dissolves ACIDS. 17 completely in boiling water. With copper acetate it gives a bluish-green precipitate, and with mercuric chloride a white one. It is not precipitated by picric acid. Carnine hydrochloride crystallizes in needles, while the platino- chloride forms a yellow powder. According to Neumeister it has no characteristic colour reactions when quite free from xanthine. Physiologically it has not a pronounced injurious effect on the system. It appears to resemble caffeine as a muscular stimulant, and to affect the heart if taken in too great excess. IV. Leucomaines of the Fatty Acid Series. — These are also found among the products elaborated by various bacteria. Trimethylamine. — This occurs normally in many tissues and secretions (c/. p. 218). It appears to be derived from the lecithins. Neuridine. — This base has been found in the human brain and in the yolk of egg, together with neurine and choline (c/. p. 305). Cadaverine. — Has been found in fresh pancreas. Gerontine — This base, which is isomeric with the two preceding, was extracted by Grandis from the liver of a dog. It crystallizes in needles which are soluble in water and in alcohol. Its hydrochloride forms small deliquescent crystals, which are soluble in alcohol. The platino-chloride crystallizes in large needles, very soluble in water. Physiologically it has a paralyzing effect on the nerve centres, but does not affect the muscles. V. Amido Acids. — GlycocoU or Amido-acetic Acid [CHg.NHg - COOH]. — This occurs in large quantity in the edible mussel and in the flesh of several mammalia. It is one of the decomposition products of collagene (pp. 23 and 154). It dissolves readily in water, but is insoluble in alcohol and ether. By adding freshly precipitated copper hydroxide to a hot concentrated solution of glycocoll, blue crystals of copper glycocoll are deposited on cooling. Sarcosine or Methyl - glycocoU [CH2(HH - CHg) - COOH], although it does not appear to occur in the animal system, may be mentioned here as a derivative of kreatinine, which is con- verted by hydration into sarcosine and urea. Leucine or Amido-caproic Acid [CeHigHOa] or “ CH - HH^ - COOH]. This is a proteid derivative, which occurs in the thyroid and other glands, in the pancreas, and in the blood of certain animals. It B 18 FLESH FOODS. crystallizes in brilliant plates whicb dissolve readily in water, and are fairly soluble in hot alcohol. It is optically active, rotating the beam of polarized light to the right, but by the action of certain mould-fungi it is converted into a Isevo-rotatory modification. The leucines formed in the pancreatic digestion of various pro- teids were found by E. Cohn * to consist of several individuals. Butalanine or Amido- valeric Acid is another proteid derivative found among the products of pancreatic digestion and in the pancreas itself. Tjnrosine [CgHiiNOg] or Para -hydoxyphenyl- a- amido -pro- pionic Acid This substance accompanies leucine and other amide bodies in the liver, pancreas, etc., and is formed in the decomposition of proteid substances, especially in the digestion. It crystallizes in glistening needles, melting at 295° C. It is fairly soluble in hot water, but insoluble in alcohol and ether. It has feeble basic and acid properties. Its hydrochloride is crystalline, very acid, and is dissociated by water. The platino-chloride is deliquescent. Tyrosine gives a red coloration or precipitate when boiled with Millon’s reagent (p. 161). Taurine or Amido-ethyl-sulphonic Acid QH /C.,H4.NH2-C00H is an amido-acid with feeble basic properties. It has been found in minute quantities in the muscles of various kinds of animals, as for instance in those of the horse and of molluscs. It cry'stallizes in large brilliant prisms which are slightly soluble in cold water, but insoluble in alcohol and ether. Lecithins. — There appear to be several kinds of lecithins yielding different proportions of fatty acids on decomposition. In 1846 a complex substance was extracted by Gobley from the yoke of egg, and similar substances have since been found in the brain, in fish-roe, in blood, and in many animal tissues. Method of Separation.— QdM.iiex t gives the following method of isolating lecithin. The yolk of the egg is extracted with ether, the extract evaporated, the residue taken up with petroleum spirit, and the liquid filtered. The filtrate is shaken several times with * Zdt. phys. Chem., 1895, 20, p. 203. t Les Toxines, p. 276. NON-NITROGENOUS ORGANIC CONSTITUENTS. 19 75 per cent, alcohol, the petroleum spirit expelled, and the solution left for several days. Cholesterin and a little lecithin separate. The clear liquid is decanted, decolorized with charcoal, and evapo- rated in vacuo at 50° C. to a syrup. The residue is taken up with ether, which on evaporation leaves nearly pure lecithin, and the latter is purified by crystallization from as small a quantity as possible of absolute alcohol at 5° C. It rapidly undergoes altera- tion, especially on heating. When treated with alkalies or acids it is decomposed with the formation of glycero-phosphoric acid, stearic and oleic acids, choline and other bases. According to Strecker, its formula is C42Hg^NPOg or Inosinic Acid. — According to Haiser,* the formula of this sub- stance is C^gH^gN^POg. The free acid is decomposed by boiling water into hypoxanthine, trioxyvaleric acid, and phosphoric acid. It is an amorphous substance, though it forms crystalline salts with alkalies. It was first found by Liebig in beef, and has since been found in varying quantity in the muscle of rabbits, cats, birds, and fish. The greatest amount recorded (0'21 per cent.) was found by Creite in the muscle of the turkey, f Reaction of Muscle. — The reaction of living muscle is neutral or slightly alkaline. But after death, and soon after rigor mortis has set in, it becomes decidedly acid, until, with the commencement of decomposition, it again becomes gradually alkaline from the formation of ammonia and substituted ammonias. By plunging the living muscle into boiling water or alcohol the production of free acid is to a large extent prevented. A high temperature accelerates the process, whilst cold retards or prevents it. The presence of oxygen appears to be non-essential, for the acidity occurs as rapidly in vacuo, or when the muscle is kept under oil or mercury, as in the open air. It is possibly due to the action of an enzyme. On the reaction of the muscular tissue Eber has based a test of the fitness of flesh for human food.J * Ann. Chem. Pharm., 158, 1871, p. 353. t Neumeister, loc. cit., p. 439. 0C2H4.N(CHg)3.0H C.— NON-NITROGENOUS ORGANIC CONSTITUENTS. t See p. 75. 20 FLESH FOODS. Free Acids of Dead Muscle. — The chief acid causing the acid reaction is a characteristic ethylidene lactic acid (CH3-CH.OH-COOH), which differs from the isomeric fermentation product in being optically active ( + ). Another lactic acid is also present, which is probably identical with the fermentation acid. The total quan- tity of lactic acid varies from OT to 1 per cent. This lactic acid was formerly regarded as being derived from glycogen, but Neumeister "*■ cites various authorities against this view. Salkowski f holds that the lactic acid is a waste product of the activity of the living muscle, being carried away by the blood, and that death puts a stop to the process of its formation. He regards its production as a function of living protoplasm, and not as the action of an enzyme. Glycogen (CgHjQOg). — This is a reserve material invariably present in muscular fibre. By the activity of the protoplasm, or of an enzyme, it is constantly being converted into glucose, w’hich, by decomposition and oxidation, serves as a source of strength. J This conversion does not immediately cease on the death of the muscle. According to Nasse’s experiments § the quantity of glycogen in the resting muscles of a frog is on the average 0‘43 per cent. In rabbits it amounts -to from 0’47 to 0'95 per cent, (r/. p. 134). "Fat. — Neumeister II regards this as a further reserve material. It is present in the connective tissue, between the fibres and in the sarcoplasma. Glucose. — This is produced by the action of the protoplasm on the glycogen, which passes through the successive stages of ery- throdextrin, achroodextrin, maltose, and glucose. If muscular tissue be instantly placed in hot water after being taken from an animal the activity of the protoplasm (or enzyme) is arrested, and only a trace of glucose will be detected. Inosite (CgHioOg-f 2H2O) is anon-fermentable isomer of glucose first discovered by Scherer in cardiac muscular tissue.H Small quantities are usually present in both striated and smooth muscles. It is optically inactive, and does not reduce metallic oxides or Fehling’s solution, though it changes the colour of the latter to green. According to Jacobsen, horse flesh contains about 0'003 per cent, of inosite. Scherer's Test for Inosite. — On adding strong nitric acid to a * Loc. eit., pp. 412-16. t Zeit.f. klin. Med., 1890, 17, Suppl. 21. i Neumeister, loc. cit., p. 424. § Pflug. Arch., pp. 97-121. II Loc. cit., p. 425. IT Ann. Chim. Phann., 1850, p. 322. MINERAL MATTER — WATER. 21 solution of pure inosite, evaporating to dryness on the water bath, moistening the residue with ammonia and calcium chloride solu- tion, and again evaporating to dryness, a rose-red coloration is obtained. _ . . ScylUte. — This substance, which is closely allied to inosite in chemical composition, is found in the muscles of certain fish. CHEMICAL COMPOSITION OF MUSCLE: II. IN- ORGANIC CONSTITUENTS. Mineral Matter. — The muscular tissue of the higher animals contains from 1 to 1 '5 per cent, of mineral matter, chiefly potassium phosphate. The ash left on incineration also contains sodium, magnesium, iron, calcium, chlorine, and traces of sulphates, prob- ably derived from the decomposition of proteid matter on ignition. The subjoined table of analyses by Katz * gives the proportion of mineral constituents in the flesh of different animals : — MINERAL CONSTITUENTS OF FLESH. Flesh of Water. Potassium Oxide. Sodium Oxide. <6 ’S O o 'B o Ph Calcium Oxide. 1 Magnesium Oxide. Phosphoric Acid (P2O6). Chlorine. Sulphur. Total. Soluble in Water. Soluble in Alcohol. Residue. Pig, . . . 72-89 0-306 0-210 0-008 0-011 0-046 0-487 0-350 0-086 0-063 0-048 0-204 O.x, . . . 75-80 0-441 0-088 0-035 0-003 0-040 0-389 0-279 0-065 0-046 0-067 0-187 Calf, . . . 75-39 0-458 0-166 0-013 0-020 0-060 0-603 0-334 0-097 0-072 0-067 0-226 Deer, . . 75-27 0-405 0-095 0-015 0-013 0-048 0-569 0-411 0-096 0-062 0-040 0-211 Rabbit, 76-83 0-479 0-067 0-008 0-026 0-048 0-579 0-469 0-068 0-043 0-061 0-199 Dog, . . . 76-42 0-392 0-127 0-006 0-010 0-039 0-612 0-345 0-110 0-065 0-081 0-227 Cat, . . . 75-14 0-456 0-097 0-013 0-012 0-047 0-461 0-351 0-066 0-043 0-067 0-219 Hen, . . 68-38 0-560 0-128 0-013 0-015 0-061 0-580 0-456 0-057 0-067 0-060 0-292 Frog, . . 81-62 0-371 0-074 0-009 0-027 0-039 0-426 0-349 0-047 0-030 0-040 0-163 Shellfish, . 80-60 0-403 0-133 0-008 0-031 0-044 0-313 0-263 0-029 0-021 0-241 0-223 Eel, . . . 63-10 0-290 0-043 0-008 0-055 0-030 0-405 0-336 0-046 0-023 0-034 0-136 Pike, . , . 79-83 0-301 0-040 0-006 0-056 0-051 0-485 0-392 0-036 0-068 0-032 0-248 Water. — The muscles of young animals always contain more than those of older animals, whilst those of embryos contain most of all. In the earliest stages it amounts to not less than 99 A per cent., which gradually falls to 81 ‘2 per cent.f The flesh of birds contains somewhat less water, and that of t Neumeister, loc. cit., p. 441. * Arch. (jes. Physiol., 1896, 3, p. 14. 22 FLESH FOODS. cold-blooded animals rather more than the flesh of mammalia. Neumeister gives the following figures ; — Mammalia. Birds. Cold-blooded Animals. Water, . 76‘5 73‘0 78'8 Solid Matter, 23'5 27'0 21'2 Of muscles in different parts of the body the cardiac muscles appear to contain the most water. Gases in Muscle. — The chief of these is carbon dioxide, the amount of which appears to be quite independent of the presence of oxygen, as much being given off in vacuo as in the air. Traces of nitrogen are also present. Summary of the Composition of Muscular Fibre. The following table is based upon those given by Kdnig,* Hofmann,! and Neumeister. J; Mammalia. Per Cent. Birds. Water, .... 74-7-78-3 Solid matter, 21-7-25-5 Organic matter. 20-8-24-5 Inorganic matter, . 0-9- 1-0 A-lknline albuminate, . Proteids insoluble in 2-85-3-01 neutral liquids, . 14-5 -16-7 Collagene, 2-0 - 5-0 Fat 0-5 - 3-7 Glycogen, . 0-3 - 1-0 Lactic acid, . 0-04- 1-0 Inosite, 0-003 Kreatine, 0-2 - 0-28 Xanthine, 0-01- 0-10 Hypoxanthiue, 0-04- 0-12 71 -7-77 -3 22 -7-28 -3 21 -7-26 -3 1-0- 2-0 Guanine, Taurine (horse), . Inosinic acid. Phosphoric acid, . Chlorine, . Potassium oxide. Sodium oxide. Calcium oxide. Magnesium oxide, Ferric oxide. • Nahr. u. Genmsmitt., ii. p. 93. t Lehrbueh der Zoocheinie, p. 104. X Phys. Chem., p. 443. Cold-Blooded Animals. 80-0 20-0 18 -0-1 9-0 1-0- 2-0 Mammalia. 0-006 0-07 0-34 -0-50 0-067 0-40 -0-50 0-02 -0-08 0-008-0-018 0-02 -0-15 0-003-0-01 CHAPTER II. STRUCTUEE AND COMPOSITION OF CONNECTIVE TISSUE AND BLOOD. CONNECTIVE TISSUE. Under this name histologists classify a number of substances, which at first sight appear to have but little resemblance to one another. These are : — a Connective tissue proper, sub-divided into white tissue, ana yellow or elastic tissue. Adipose tissue. Cartilage. Osseous tissue, or bone. CONNECTIVE TISSUE PEOPEE. In one or other of its forms connective tissue is present in almost all parts of the body, its function being to connect or hold together adjacent organs or parts of organs. In certain parts it is soft and tender ; in others, such as the tendons and ligaments, it is hard, tough, and of great strength. It is composed of numerous fine fibres, some of which lie parallel, while others cross one another. The fibres composing the yellow or elastic tissue are fewer in number than the white fi^bres, from which they also differ in colour and in their behaviour on treatment with acetic acid, and on boiling with water. The cells of connective tissue primarily contain granular protoplasm, in which a nucleus may be observed. White Fibres.— These consist of an albuminoid substance, collagene (koAAo, glue), which when boiled with ^ water yields gelatin. The latter substance is obtained in quantity by boiling tendons (which are chiefly composed of white fibres) with water, preferably under pressure (c/. p. 154). Elastic Fibres. — These, unlike the white fibres, do not swell up and become transparent on treating the connective tissue with acetic acid, and hence their presence in tissue can be readily demonstrated by means of that reagent. After prolonged boiling 24 FLESH FOODS. with water, the white fibres can be completely dissolved out from the connective tissue in the form of glue or gelatin, leaving behind the elastic fibres, w'hich are composed of an albuminoid substance named elastin {cf. p. 154). Mucin. — All connective tissue proper contains a small pro- portion of this proteid substance, which can be isolated by macerating the tissue for several days in lime Avater, and precipi- tating the proteid by the addition of a dilute acid from the alkaline solution thus obtained. It occurs in larger proportion in embryonic connective tissue, and is a constituent of the mucus with which epithelial cells are covered. It is not digested by an acid solution of pepsin, but dissolves in alkaline trypsin. According to Fischer and Krause * the specific gravity of con- nective tissue varies from 1-1189 to 1-1065, the mean being 1-1141. ^ ADIPOSE TISSUE. Distribution of Fat in the Body. — Fat is found in the animal body either in a state of solution or suspension in the various Lonneclive lUstw Fibrils, Fio. 8. — Fat cells, some show- ing nucleus. The central one shows ‘ margariu ’ crystals. X 100. {Stirling.) Fio. 7. — Fat cells from Rabbit. {Landois and Stirling.) fluids, or deposited in cells. In the latter case the cells are often those of the connective tissue, in which the protoplasmic contents have been gradually displaced by the fat, leaving the original cell- walls in their former state. The condition of the fat cells under- * Falck, Das Fleisch, p. 352. COMPOSITION OF ANIMAL FAT. 25 goes fluctuations according to the state of nutrition and habits of the animal. For instance, it is well known that wild animals possess, as a rule, much less fat than do animals of the same species in captivity. The fat cells usually occur in groups, sup- ported by the fibrous substance of the connective tissue. Fischer and Krause give the following figures for the specihc gravity of adipose tissue: — Maximum, 0'9254; mean, ; minimum, 0-9243. , Composition of Animal Fat. — The subject of fats and oils, even when confined to those found in the animal kingdom, is far too wide to be treated of at length in the present work, and for a fuller description the reader must consult one of the numerous manuals dealing specially with their composition and analysis. Animal fats (excluding milk fat and waxes, such as beeswax and sperm oil) consist almost entirely of compounds of glycerin with higher fatty acids (chiefly palmitic and stearic) of the acetic series (C„H,„02), and of compounds with unsaturated acids of different series (chiefly oleic acid), together with traces of lower volatile acids. Judging by the large proportion of iodine absorbed bv the more liquid portion of the fatty acids of many animal fats, glycerides of acids more unsaturated than oleic acid must be fre- quent constituents. Kurbatoff* claims to have isolated linolic acid from the fat of the seal and Caspian hare, and Famsteiner has found it in lard, ox tallow, and horse fat (cf. page 101). Recently Amthor and Zink f have found that the fats of certain wild animals and birds, noticeably those of the wild boar, hare, wild rabbit, and blackcock, have remarkable drying properties and very high iodine values, from which facts the presence of a still more unsaturated acid, possibly in the same series (CnHjn.eO^) as the linolenic acid of linseed oil, may be inferred. This has received confirmation from the work of Famsteiner (page 101), who has found traces of linolenic acid in lard and tallow. Amthor and Zink also obtained with several of the lesser known animal fats in a fresh condition {e.g. fox, cat, etc.) a high acetyl value, and it is thus not improbable that hydroxylated fatty acids, like the ricinoleic acid of castor oil, may occasionally be normal constituents. J So far as is known the glycerin in animal fats is always in com- bination with the fatty acids in the form of triglycerides, and yO.R .4—O.R are said to have \O.H although diglycerides of the type * BericMe, 25, p. 506. + Zeit. anal. Chem., 37, pp. 1-17. Analyst, 1397, 22, p. 75. t Cf. note, p. 58. 26 FLESH FOODS. been found in old vegetable oils, they do not appear to have been normal constituents. It is not kno^vn with certainty whether the three acid radicles in a triglyceride invariably belong to the same fatty acid, so that the glycerides are of the type yO.R in which R represents the radicle of any one acid, say stearic acid, or whether, in some cases, two of the radicles belong to one acid and the third to another; or whether all three radicles belong to different acids, say oleic, palmitic, and .O.R^ stearic acids, forming glycerides of the type CjHg^O.i?,. There is evidence,* however, which tends to prove that tri-acid glycerides exist in butter fat, so that it is not improbable that similar com- pounds may occur in body fats. As confirmatory evidence it may be mentioned that Hehner and Mitchell have separated bromine compounds from linseed oil and marine animal oils, which have the characteristics of bromides of mixed glycerides. As to the relative proportion of solid and liquid fatty acids, considerable variations are found not only in the fat of animals of different species, but also in the fat of different individuals of the same species, and even in the fat from different parts of the body of the same animal. In like manner, the amount of stearic and palmitic acid in the solid portion of the fat, and of the oleic and linolic acid in the liquid portion shows enormous varia- tions, t Stearic acid, for instance, may vary from 0 to about 25 per cent, in the fat from different parts of the same sheep,! and it is a well-recognized fact that the fat of American pigs contains considerably more of a liquid fatty acid with a greater deo^ree of unsaturation than oleic acid than does the fat of European pigs. § The composition of fish oils (cod-liver, etc.) and of marine ani- mal oils (whale, etc.) is still more complex than that of land animals, and much of the work that has been done on the subject is either unconfirmed or has been disproved. Speaking generally, fish oils appear, for the most part, to consist of glycerides of various unsaturated fatty acids, together with smaller quantities of the glycerides of saturated acids (palmitic, etc.), some of which are deposited when the oil is cooled below the ordinary temperature. Many of the unsaturated acids are apparently of a different character to those found in the fat of land animals. Cod-lix er * Analyst, 1898, p. 317. + Of. p. 54. X § von Raumer, Zeit. angew. Chem., 1897, Twitchell, Analyst, 1895, xx. p. 165. Analyst, 1896, 21, p. 327. pp. 210-215 and 247-254. ANIMAL FAT — CAKTILAGE. 27 oil for instance, appears to contain a fatty acid of the series C which is not identical with Imolenic acid, for Hehner and ‘Mitchell have prepared from that bromide with the same composition as that compound to be' obtained from linseed oil, but with very different ^^Fahrion,t^oo, claims to have discovered an unsaturated fatty acid (iecoric acid) with the formula CigHgoOa, and another un- saturated acid with the composition Ci^HggOg (asellic acid) in cer- tain fish oils. THE PRINCIPAL ACIDS AND GLYCERIDES OF ANIMAL BODY FAT. I Saturated Fatty Acids. Formula. Specific Gravity. Melting Point. Solidify- ing Point. Mol. Weight. Found in AoETio Series (CnH2n02). Palmitic Acid, Tri-Palmitin, . C16H32O2 CsHsCO. Ci6H3,0)3 0'8627at4?-°C. 62° C. 62°-64° C. 45°-47° C. 256 804-2 Most animal fats. Stearic Acid, Tristearin, <^18113602 C3H6(O.Ci8H360)3 0-8454 at72°C. 71-6° C. 71-6° & 65° » * • 284 888 Most animal fata. TJnsaturated Fatty Acids. i. Aortlio Series, CnH2n-202. Oleic Acid, . Triolein, C18H3402 C3H6(0. C] 80330)3 0-898 at 14° C. 0-900 at 16° C. 14° C. 4°C. 282 882 Most animal fats. il. Linolic Series, CiiH2n-*02- Linolic Acid, Trilinolein, . C18H3202 0-920 C. at 14° C. Liquid at -18° C. •• 280 Horse fat, lard, ox- tallow. iii. LiNOLENic Series, CnH 71— O2. (Linolenic Acid), . (Jecoric Acid), CisHsqOs 0-9228 at 16-5° C.§ •• 278 Lard, ox- tallow, marine animal oUs. iv. htdroxylated Series, Series CnH27i-203. {Bicinoleic Acid), . C18H3403 I 0-9400 at 16° C. •• •• •• * Analyst, 1898, p. 317. t Jour. Soc. Chcm. Lid., 1893, pp. 935 and 938. X This table does not include the fatty acids present in the milk fat of different animals (butyric acid, etc.), since the subject of milk does not come within the scope of the present book. § Hehner and Mitchell, Analyst, 1898, p. 313. 28 FLESH FOODS. ^lany of the fish oils contain considerable proportions of un- saponifiable matter, noticeably cholesterin, an alcohol which also occurs, though to a lesser extent, in the fat of land animals. Sperm oil and bottle-nose oil differ from marine oils properly so called in containing hardly any glycerides, and are, in fact, liquid waxes. As an examination of the characteristics of the fat attached to or contained in the muscular tissue may often be of use in iden- tifying the kind of flesh, the formulas and some of the physical constants of the chief fatty acids and triglycerides which have been found or which are likely to be met with in the body fat of some of the terrestrial animals more commonly used as food are given in the accompanying table (see p. 27). The physical and chemical constants of the fat of various individual animals are given on pages 47-66, and methods for determining these constants in Chapter V. CAKTILAGE. Structure. — Cartilaginous tissue consists essentially of a ground- work or mairix surrounding certain cells which contain protoplasm in which one or two nuclei can be observed. From the different characteristics assumed by the matrix, cartilage has been classified into the following groups ; — Hyaline, in which the matrix is a semi-trausparent, homogene- ous substance, often resembling ground glass, and occasionally of a fibrinous nature. Cellular, in which the matrix is transparent, and the envelope or capmle surrounding the cells is thin. White-fibre Cartilage, in which the matrix is composed of a large number of fibres which are apparently of the same nature as those of connective tissue proper. Elastic or spongy, in which the matrix is made up of a network of elastic fibres. Composition. — The cartilage taken from different parts of the body varies considerably in composition, as is shown by the results of the analysis made by Hoppe-Seyler.* Organic Mineral Water. Matter. Matter. Costal Cartilage, . . . 67 67 30‘13 2’20 Articular „ from knee-joint, 73'59 24‘87 1‘54 The mineral matter of cartilage consists principally of sodium and potassium sulphates, with smaller quantities of sodium chloride and of the phosphates of sodium, calcium, and magnesium. * Quoted by Gamgee, Phys. Chem., p. 268. CARTILAGE— OSSEOUS TISSUE. 29 C7iore^Zn«.— The matrix of cartilaginous tissue, when subjected to long-continued treatment with boiling water, ^elds a glue-li -e substance formerly known as chondrin, but which has been shown to be a mixture of gelatin and soluble alkali salts oiclimdrmtm sulphuric add. According to Morner,* this proteid, which belongs to the class of glycoproteids, is present in all the varieties of Soluble Proteids. — Besides soluble chondroitin compounds, there are various soluble proteid substances {e.g. globulins) always pre- sent in cartilage. , . , . , i £i. i, Elastin.—This albuminoid is contained in the residue left when part of the cartilage is converted into the so-called chondnn by long-continued boiling with water. ‘ Albumoid.’ — This is the name given by Morner f to a charac- teristic proteid which appears to be an invariable constituent of all adult mammalian cartilage. It is quite insoluble in neutral liquids, and is closely allied to the albuminoids elastin and Jceratm, from which, however, it differs in composition and in being soluble in gastric juice. OSSEOUS TISSUE, OE BONE. Structure. — On the exterior of all bones is a fibrous membrane, the periosteum, and between the joints of connected bones a layer of cartilaginous tissue. Inside the bone there is often a channel, the medullary cavity, the ends of which become broken up by partitions of the bony substance into a large number of very small cavities, the cancelli. In some bones, however, such as the ribs, the medullary cavity is absent, and the cancelli take its place throughout the length of the bone j and in some of the smaller bones there is not even the cancellated structure. In the medullary cavity lies the medulla, or marrow, a mass of connective tissue containing an abundance of fat cells. Minute channels, containing blood-vessels, and known as the Haversian canals, are found in the walls of the medullary cavity, and the bony substance arormd these has a peculiar concentric formation, consisting of what are known as lamellae. These contain small openings, lacunae, which are connected with other minute canals, called the canaliculi. Huxley I concisely sums up the general structure of long bones with cartilaginous ends in the following words ; — “ The bone may be regarded as composed of, a, an internal, thick cylinder of vas- * Zeit. phys. Chem., 1895, 20, pp, 361, 362. + Skand. Arch.f. Phys., 1895, 6, pp. 378-400 ; quoted by Neumeister, loc. cit., 453. + Elementary Physiology, p. 330. 30 FLESH FOODS. cular medulla ; ft, an external, hollow, thin, cylindrical sheath of vascular periosteum, completed at each end by a plate of articular cartilage ; c, of a fine, regular, long-meshed, vascular network. Fiq. 9. — Transverse section of shaft of human femur. E, Haversian canals ; c, lacuntB with bone-corpuscles ; a, lacunae with recurrent canaliculi ; s, intermediate lamellae ; 2, confluent lacunae, x 300. (Stirling.) which connects the sides of the medullary cylinder with the periosteal sheath of the shaft; d, of a coarse irregular vascular Fig. 10. — Cancellated bone. C, cancellus ; cc, calcified cartilage ; B, bone; 0, osteoblast. (Stirling.) meshwork occupying at each end the space between the medullary cylinder and the plate of articular cartilage, and connected with the periosteum of the lateral parts of the articular end ; e, of the 31 COMPOSITION OF BONE. hard, perfect osseous tissue which fills the meshes of these two ’^^Smposition.— Orr/amc .Basis.— The mineral substances of the bone can be removed by treatment with mineral acids, a^d an orcranic residue is left which retains the form of the original bone. This substance, formerly known as ossem, yields gelatin on treat- ment with boiling water, like connective tissue proper, it also contains a certain amount of a substance akin to elastin. According to Hoppe-Seyler, from 25 to 26 per cent, of the organic substance of bone consists of collagene, the other constituents amounting to about 8 per cent. Water.— The quantity of this shows a considerable variation even in the bones from different parts of the same frame. Scho , for example, found a variation of from 15 to 44 per cent, in the different bones of a dog. Mineral Basis. — On calcining bone the organic matter is re- moved, and the mineral framework left behind. This consists principally of calcium phosphate, with calcium carbonate and magnesium phosphate, and small amounts of compounds of potas- sium, sodium, chlorine, and fluorine. The sodium amounts to about 1 per cent, of the total ash, the potassium to about 0’25 per cent., while the fluorine does not, as a rule, exceed 0'05 per cent., though in exceptional cases it may amount to OTO. Chlorine is only present in traces. t-. * The following figures, selected from a long table given by Fremy, show the proportion of mineral matter and some of its constituents in the bones of various animals : — MINERAL MATTER OF BONE. Bone. Per Cent. Total Mineral Matter. Calcium Phosphate. Magnesium Phosphate. Calcium Carbonate. Rabbit (femur), 66-3 58-7 IT 6-3 Calf (5 months old, femur), 69 1 61-2 1-2 8*4 Cow (old, femur), . 71-3 62-5 2-7 5*9 Ox (humerus). 70-4 61-4 17 86 Bull (femur), . 69-3 59-8 1-5 8*4 Lamb (femur), 67-7 60-7 1*5 8T Sheep 70-0 62-9 1-3 77 Turkey, .... 67-7 63-8 1-2 5-6 Codfish, .... 61-3 65T 1-3 7-0 * Ann. do Chim. et Fhys., iii. Ser. 42, 47-107. 32 FLESH FOODS. It is noteworthy that the percentage of the different constituents calculated on the amount of bone-ash show a remarkably constant ratio in the case of different animals. Thus Zalesky* gives the following figures : — Calcium Phosphate. Magnesium Phosphate. Calcium combined with COj, Cl, and F. Carbon Dioxide. Man, 83-89 1-04 7-65 5-73 Ox, 86-09 1-02 7-36 6-20 Guinea-pig, . 87-38 1-05 7-03 Turkey, . 85-98 1-36 6 '32 6-27 Gabriel, t also, gives results in substantial agreement with these ; — Calcium Oxide. Phosphoric Acid. Magnesium Oxide. Ox, .... 51-28 37-46 1-05 Goose, 61-01 38-19 1-27 Tlie age of an animal appears to cause but little variation in the composition of the mineral matter of the bone, judging by the results of E. Wildt, J who examined the bones of twelve rabbits, varying in age from one day to four years, with the following results : — Calcium Oxide. Phosphoric Acid. Magnesium Oxide. 51-91-52-69 39-78-42-20 0-83-r38 THE BLOOD. Quantity in the Body. — Speaking generally, the blood con- stitutes about one-twelfth of the total weight of the body, but the quantity depends very largely on the condition of the animal, and on the length of time that has elapsed since it has taken food and drink. The amoimt of blood which is lost when an animal is slaughtered is only a portion of the total quantity, a consider- able proportion being retained by the flesh and va,rious organs. According to Fischoeder § the quantities which can be collected on slaughtering various animals are on the average': horse, * Quoted by Neumeister, Ldirhuch, p. 456. t Zeit, phys, Chem., 1894, 18, pp. 281, 282. X Neumeister, loc. cit, p. 457. § Handlmch der Fleischbeschau, p. 23. THE KED CORPUSCLES. 33 20 to 25 litres; ox, 15-20 litres; pig, 2-3 litres; sheep, 1 to 1^ litre ; and calf, 1 to 1 J litre. General Characteristics. — The specific gravity of blood shows considerable variation, even in different animals of the same species, the sex, nourishment, and age of the individual all having an influence. The normal limits may be taken as 1’045 and 1'075. Odour. — Blood has a smell characteristic of the animal from which it was derived. This becomes much more apparent on adding dilute sulphuric acid and gently warming. Reaction to Litmus. — The chemical reaction is feebly alkaline on account of the presence of sodium carbonate and sodium phosphate. According to Winterstein "*■ the- alkalinity of rabbits’ blood is equivalent to 0‘165 gramme of sodium hydroxide in 100 c.c. The alkalinity of the blood differs no more in different species of animals than in individuals of the same species. Colour. — This depends chiefly on the quantity of haemoglobin in the blood. As a rule the blood of carnivorous animals is darker than that of herbivorous animals, and the male has usually darker coloured blood than the female. Structure. — Blood consists of an almost colourless liquid, the plasma, in which are suspended small particles — the colourless and red corpuscles. From the plasma an albuminous substance, fibrin, is readily separated, while the clear residual liquid is known as the serum. When the coagulation or clotting of blood occurs, a solid mass is formed, consisting of the red corpuscles bound together in a network of fibrin. Conditions Affecting Coagulation. — The coagulation of blood is accelerated by such conditions as moderate warmth (39°-49° C.), dilution with not more than twice its volume of water, contact with foreign substances, and exposure in shallow dishes to the action of the atmosphere. It is retarded by cold, heat, addition of more than twice its volume of water, imperfect aeration, as in cases of death by suffocation, and by the addition of alkaline salts, strong acids, or alkalies. THE RED CORPUSCLES. In man and most mammals these are round , double-concave discs, but in the blood of the camel and llama, and in that of birds, fishes, reptiles, and amphibia, the discs are elliptical. There is a great difference both in their size and number in different animals. As a general rule the blood of reptiles and amphibia contains comparatively few, while they are especially numerous in the blood , * Zeit. phys. (Jhem., 1891, 15, p. 505. C 34 FLESH FOODS. of carnivora. The accompanying figure represents the appearance of the red and white corpuscles of human blood. 11. Human red and white blood corpuscles, a, red corpuscles, seen on the flat ; b, in profile ; c, a rouleau ; d, three-quarter face ; e, /, crenated ; g, spherical ; Z, large white corpuscles ; I, small white corpuscles ; p, granu- lar leucocyte ; 71, free granulations, x 1000. {Stirling.) According to Bunge,* the proportion of blood corpuscles in 100 parts of blood is, in the case of different animals, as follows: horse, 53; pig, 43’5 ; ox, 35; dog, 35 7. Arouet* found human blood to contain on the average 48 per cent. Colour. — This is due to hmmoglobin, w’hich, in the form of oxyhsemoglobin, composes about 1 3 per cent, of the total blood, 40 per cent, of the moist corpuscles, and 95 per cent, of their total organic matter. The other constituents of the corpuscles are grouped together under the term stroma. Examined under the microscope, the individual corpuscles are transparent, and have a faint yellowish-green colour. OxyluzmogloUn.—Th.\s. is the colouring matter of the bright red arterial blood. It can be isolated from the stroma in a crystalline form. The blood corpuscles are separated from the defibrinated blood by means of centrifugal action, washed free from serum with a solution of sodium chloride, shaken with ether, transferred to a separating funnel with a small quantity of water, and the lower aqueous solution filtered. The filtrate is coojed to zero, mixed with U fourth of its volume of alcohol also at 0° C., and allowed to stand for twenty-four hours at a temperature of from -2° to — 10° C The crystals of oxyhmmoglobin which have deposited are pressed between filter paper, and purified by recrystallization. Differences in the Oxyhsemoglobin Crystals obtained from the Blood of Different Animals.— The crystals obtained by the method described above vary greatly in chemical composition, crystalline form, and solubility (see fig. 12). _ r n As an instance of the variation m composition the following * Quoted by.Neumeister, Fhys. Chem., p. 559. HEMOGLOBIN CRYSTALS FROM BLOOD. 35 analysis of different specimens of crystals from horse-blood may be quoted ; — Carbon. Iron. Sulphur. Hoppe-Seyler, . . 54'87 0'47 0'65 Zinoffsky, . . . 51 '15 0'34 0'39 The water of crystallization in different varieties of oxybsemo- globin varies from 3 to 10 per cent. Fig. 12.— Haemoglobin crystals from Blood, a, 6, human ; c, cat ; d, guinea-pig ; e, hamster ; /, squirrel. {Landois and Stirling.) As regards crystalline form, tbe oxybsemoglobin of human blood is obtained in microscopic rhombic needles, and that of the horse in quadrilateral prisms often several millimetres in length. The blood of the guinea-pig, rat, and many birds yield rhombic tetra- hedra, while from that of the squirrel hexagonal plates are deposited. The difference in solubility is shown by the fact that the crystals are easily prepared from the blood of the guinea-pig, rat, and squirrel, and fairly readily from that of the horse, dog, cat, and mouse, but only with considerable difficulty in the case of the pig and ox. Identification of Oxyhxmoglobin. — The most characteristic pro- 36 FLESH FOODS. pcrty of oxyhsemoglobin is its absorption spectrum. In a suitable degree of dilution it shows two bands, one at D, and the other, which is broader and less defined, at E. On continued dilution the latter is the first to disappear {cf. fig.- 15). Quantitative Estimation of Oxyhmmoglobin. — The amount of oxyhsemoglobiu in blood, or in liquids containing blood, can be approximately estimated by determining the amount of iron in the ash. The oxyheemoglobin from horses’ blood contains from 0'34 Pjo, 13. Fleischl’s hsemometer. K, red-coloured wedge of glass moved by ji ■ G mixing vessel with two compartments, a and a' ; M, table, with hole to read off percentage of haemoglobin on scale P ; T to move K ; S, mirror of plaster of Paris. (Landois and Stirling.) to 0’47 per cent, of iron, and 0‘42 per cent, may be taken as the average amount in dry oxyhmmoglobin in general. The method most frequently employed, however, is Hoppe- Seyler’s colorimetric process,* or one of its modifications. This consists in diluting a measured quantity of blood with water until it matches the colour of a solution containing a knowm quantity of pure crystalline oxyhemoglobin. The Nessler tubes, and the process recommended by Hehner t for the determination of ammonia in water, are well adapted for this colorimetric process. G. divert advocates the use of Lovibond’s tintometer and standard colour glasses, and, according to Halliburton, t this gives a better result with diluted blood than any other colorimetric process. * Zeit. physiol. Chem., 1892, xvi. p. 505. t Analyst, 1877, ii. p. 180. X Kirk’s Physiology, p. 597. DEKIVATIVES OF HAEMOGLOBIN. 37 FleiscH’s hsemometer, which is one of those most frequently- used, is illustrated in fig. 13. _ Reduction of OxylisemogloUn.—'YhQ oxygen in oxyhsemoglobin is only feebly combined, and is completely liberated in vacuo. It is known as ‘respiratory oxygen,’ and the iron in the proteid mole- cule probably plays some part in its addition. Besides being re- duced in a vacuum, oxyhsemoglobin is also converted into hsemo- globin by passing a current of an inert gas such as hydrogen, carbon dioxide, or nitrogen through a solution of it, by the addi- tion of reducing agents such as ammonium sulphide, and by the products of putrefaction. ‘ Ptseudo-HscmogloUnJ — Certain reducing agents, such as potassium hydro-sulphide, only cause a partial reduction of oxyhsemoglobin, and an intermediate product is formed with the same spectrum as the com- pletely reduced oxyhsemoglobin, but still containing some oxygen. HaemogloUn. — - This is obtained by the complete reduction of oxyhcBmoglobin, and is the dark purple colouring matter of the venous blood. It combines energetically with oxygen and carbon monoxide. Its spectrum is shown in fig. 16. Hmmatin. — On heating an aqueous solution of oxyhaemoglobin to about 80° C. it undergoes decomposition, and an amorphous pre- cipitate is deposited, which has a composition corresponding to the formula Cg2H32N404Fe. Hsematin has a bluish-black metallic lustre, and can be heated to 180° C. without decomposition. Heemin. — This is the hydrochloric acid compound of hsematin anhydride, and has the formula C32H3oN403Fe.HCl. It is precipi- tated in characteristic crystals on heating a solution of oxyhsemo- globin in glacial acetic acid containing a little sodium chloride. The crystals are minute rhombic plates with a bluish-black metallic lustre. They are insoluble in water, alcohol, and ether, slightly soluble in acetic acid and dilute mineral acids, and easily soluble in alkaline liquids and acidified alcohol. The difference in the form of hjemin crystals from different kinds of blood is seen in fig. 14. Hacmatin Acid. — This has recently been prepared by Kuster * by oxidizing htematin dissolved in acetic acid. It is a crystalline, dibasic acid, and has the formula CgH^g^s- Hxmo-chromogen, or reduced hsematin, is produced by the action of acids and alkalies on hsemoglobin in the absence of oxygen. In alkaline solution it rapidly absorbs oxygen from the air, changing to hsematin. In acid solution it gradually loses its iron, and becomes converted into hsemato-porphyrin. Hizmato-'por^lvgrin. — When hsematin or hsemin crystals are treated with concentrated sulphuric acid, fuming hydrochloric acid, or acetic acid and hydrobromic acid, the iron is completely * Berichte, 1897, p. 105. 38 FLESH FOODS. split off, and, ou dilution, a colouring matter is obtained. This has the composition C32HggN40g, and was named haemato-porphyrin by Hoppe-Seyler. Meths^oglohin. — By acting on the colouring matter of blood with oxidizing agents, such as potassium permanganate, hydrogen peroxide, or ozone, the oxyhsemoglobiu undergoes a molecular change, and an isomeric compound with a distinctive spectrum is formed. It can be reconverted into oxyhajmoglobin by dissolving Fig. 14.— Hamin crystals. 1, human ; 2, seal ; 8, calf; 4, pig ; 6, lamb ; 6, pike ; 7, rabbit. {Landois and Stirling.) it in dilute sodium hydroxide solution, and adding a reducing agent such as ammonium sulphide. Carbon Monoxide Hxmoglolnn is a compound of htemoglobin with carbon monoxide, and is produced in the blood in cases of poisoning by that gas (r/. fig. 15). Spectra of Haemoglobin and its Derivatives. — The spectra of hajmoglobin and of some of its most characteristic compounds are shown in the accompanying figure (fig. 15). THE WHITE CORPUSCLES. The white corpuscles, or leucocytes, are present in the blood in much smaller qtiautity than the red corpuscles, the normal ratio being about I : 350. They are also considerably larger, being usually about diameter. In form they are irregular, and are continually altering their shape after the manner of the amoeba. They are composed of a granular sub- stance of a protoplasmic nature containing a rounded nucleus, which can readily be made visible by treating the white corpuscles with very dilute acetic acid. This nucleus assumes a darker colour than the rest of the corpuscle when stained with carmine. Fig. 16 represents the appearance of the white corpuscles when treated with different reagents. 39 SPECTKA OF HEMOGLOBIN COMPOUNDS. OTHER SMALL BODIES IN BLOOD. In addition to the corpuscles, blood contains small irregularly 4ed botes plalus or • has been g.ven. There f ooeeur Red. Orange. Yellow. ^eein ^ Oxyhaemo- globin, 0-8 %. Oxyhsemo- globin, 0-18 %. Carbonic Oxide Haemo- globin. Reduced Haemo- globin. Methaemo- globin in Acid Solu- tion. Haematin in Alkaline Solution. Haemo- chromogen in Alkaline Solution. Reduced Haematin. A a B C D E F Fig. 15. — Spectra of haemoglobin and its compounds. {Landois and Stirling. ) and there small particles, some of which contain a brown or black pigment. These are about five times the size of the red cor- puscles, and possibly have their origin in the spleen. The colour- less particles which are met with in the blood are probably frag- ments of broken-up white corpuscles. 40 FLESH FOODS. THE BLOOD PLASMA. This contains about 8 per cent, of solid matter, chiefly of a pro- teid nature. The amount of inorganic matter is about 0‘75 per cent. Proteids of the Plasma. — The albuminous substances contained in blood plasma are chiefly globulins. Serum albumin is also present in small proportion, the ratio between it and the globulins ' varying in different species of animals. The plasma of cold- blooded animals contains the least serum albumin. A C Fig. 16. — "White corpuscles under different reagents. A, human white blood corpuscles without any reagent ; B, after the action of water ; 0, after acetic acid ; D, frog’s corpuscles ; changes of shape due to amoeboid move- ment ; E, fibrils of fibrin from coagulated blood ; F, elementary granules. (Landois and Stirling. ) Metaglohulin or Fibrinogen. — This is the most important of the proteid constituents. It can be separated from the globulins and serum albumin by adding sodium chloride to its solution. When the amount of sodium chloride reaches 16 per cent., the fibrinogen is precipitated, whilst the globulins remain in solution until the liquid has been saturated with salt. On heating fibrinogen in aqueous solution to from 56° to 60° C., it is decomposed into tw'o globulins, one of which is precipitated, w'hile the other remains in solution until the temperature reaches 65° C. After removing the sodium chloride by means of dialysis, fib- rinogen is obtained in white flakes, which readily agglomerate into PROTEIDS OE’ BLOOD PLASMA. 41 an elastic mass. When left in water it undergoes an alteration and becomes insoluble in dilute salt solutions.^ • i ‘ Thrombin ’ or ‘ Fibrin Ferment’ — According to A. Schmidt and others the coagulation of fibrinogen is brought about by an enzyme, the so-called ‘thrombin’ or ‘fibrin ferment,’ which is derived from a substance of a similar nature, ^prothrombin,’ con- tained in the corpuscles of the blood, more especially the white corpuscles. It can be obtained from the defibrinated blood or from the blood serum by leaving the liquid in contact with strong alcohol for several months, and extracting the air-dried deposit with a little water. This aqueous extract contains the active enzyme, and rapidly causes a solution of fibrinogen to coagulate in the presence of a small quantity of calcium chloride. Fibrin. — On coagulation fibrinogen is decomposed into two pro- teid bodies — fibrin and fibrin globulin. The quantity of fibrin obtained from blood only amounts to from 0‘1 to 0'4 per cent., although from its voluminous nature it appears considerably more. When deposited during the coagulation of blood it is very impure, being mixed with serum globulin and constituents of the white corpuscles. The pure substance can be prepared by treating a solution of pure fibrinogen containing calcium chloride with the fibrin ferment. Pure fibrin is insoluble in water and (at first) in neutral saline liquids, but is completely soluble in dilute acids and alkalies after remaining in contact with them for some days, and in dilute salt solutions after some weeks. Fibrin Globulin. — This substance is formed together with fibrin during the coagulation of fibrinogen. It is also produced together with another proteid on heating fibrinogen to 56-60° C. On evaporating its aqueous solution fibrin globulin is converted into a substance of an albumose character. Paraglobulin or Serum Globulin. — When blood coagulates (with deposition of the altered fibrinogen) this proteid is found in an unaltered state in the serum. A solution of paraglobulin in a 10 per cent, solution of sodium chloride coagulates at 75° C. It can be precipitated by adding to its solution an equal volume of a saturated solution of ammonium sulphate. Serum Albumin. — This is also found in the serum after coagula- tion of the blood and can be isolated by precipitating the globulins by saturating the liquid with magnesium sulphate at 30° C., and then adding dilute acetic acid to the filtrate. Pure serum albumin coagulates from its aqueous solution at 50° C., but when salts are also present the coagulation temperature is considerably raised. Yellow Colouring Matters of Blood Serum. — The faint yellow colour of the blood serum of man and most animals is due to the * Neumeister, loc. cit., p. 594. 42 FLESH FOODS. presence of a dissolved colouring matter (lipoclirome), which can he extracted by means of amyl alcohol. This colour is much more pronounced in certain animals than in others. It is well marked, for instance, in the serum of the ox, pigeon, hen, and tortoise, whilst rabbits’ serum is almost colourless. Under the name ‘lipo- chrome’ are classified various non-nitrogenous animal colouring matters, the constitution of which has not been determined. Hammarsten * found that the blood serum of the horse always contained a small quantity of hili'i-uhin, one of the colouring sub- stances of the bile. The amount of this appears to vary in different horses. Fat. — This may amount to as much as 1 per cent, in the case of animals whose food has contained a large amount of fat. It can be extracted from the serum with ether. Cholesterin and lecithin are invariably present in small pro- portions. Glucose. — This is a constant constituent in varying quantity in the blood serum of different animals, but it never appears to exceed 0‘2 per cent, of the original blood. Other reducing bodies, in- cluding gums, are also present in traces. Traces of sarcolactic acid, kreatine, uric acid, and urea are also present. Inorganic Constituents of Plasma. — These are found partly in combination with the proteids and partly in the free state. Bunge t obtained the following mean results in his examination of the blood serum of the horse, ox and pig : — Potassium oxide, 0'026 ; sodium oxide, 0’435 ; calcium oxide, 0'013 ; magnesium oxide, 0’004 ; chlorine, 0 369 ; phosphoric acid, 0'022 ; total, 0-869 per cent. The sodium chloride is in the free state, and not in combination with the proteids. A considerable proportion of the sodium is in the form of sodium bicarbonate. In addition to these salts traces of fluorine compounds have also been found. Gases in Blood. — These are oxygen, carbon dioxide, and nitro- gen. Arterial blood contains more oxygen than venous blood, while the latter is richer in carbon dioxide. Pfl tiger J obtained from the arterial blood of a dog, 21 per cent, by volume of oxygen, and from the venous blood 1 2 per cent. In the case of the carbon dioxide the respective quantities were 38 and 46 per cent, by volume. There is not this difference to be observed in the amomit of nitro- gen, w-hich, in each kind of blood, is about 2 per cent. Tlie carbott dioxide is present partly in the form of sodium bicar- bonate, and the remainder is probably loosely combined with some of the proteid substances. Practically the whole of the oxygen is in chemical combination with the hcemoglobin of the red corpuscles. * Neumeister, loc. cU., p. 585. t 2eit. Biol., 1876, 12, p. 191. + Neumeister, loc. cit., p. 600. CONSTITUENTS OF BLOOD IN OXEN AND HOESES. 43 ULTIMATE COMPOSITION OF BLOOD. According to the analysis of Playfair and Boeckmann, the dried blood of the ox has the following elementary composition : — Car- bon, 57-9 ; hydrogen, 7'1 ; nitrogen, 17-4; oxygen, 19'2; ash, 4-4 per cent. This would correspond to the formula C4gH39NjgOi5, ivhich is identical with that found by the same chemists for flesh. PEOXIMATE COMPOSITION OF BLOOD. E. Abderhalden * gives the following table of the quantity of the various constituents in the blood of the ox and horse. COMPOSITION OF THE BLOOD OF THE OX AND HOESE. Grammes in 1000 Grammes. Ox. Horse. Blood. Blood Serum. Blood Corpus- cles. Blood. Blood Serum. Blood Corpus- cles. Water, 808-9 913-64 591-858 749-02 902-05 613-15 Solid Matter, . 191-1 86-36 408-141 250-98 97-95 386-84 Haemoglobin, 82-0 251-92 166-9 315-08 Albumin, . 90-9 72-5 129-02 69-7 84-24 56-78 Sugar, 0-7 105 0-526 1-176 . . • Cholesterln, 1-935 1-238 3-379 0-346 0-298 0-388 Lecithin, . 2-349 1 675 3-748 2-913 1-720 3 973 Fat, . 0-567 0-926 • • • 0-611 1-300 . . • Phosphoric Acid in Nucleins, . 0 0267 0-0133 0-0546 0-060 0-020 0-095 Sodium Oxide, . 3-635 4-3,12 2-2322 2-091 4-434 . • . Potassium Oxide, 1-407 0-255 0-722 2-738 0-163 4 935 Iron Oxide, 0-544 • • « 1-671 0-828 1-563 Calcium Oxide, . 0-069 01194 • • « 0-051 0-1113 ... Magnesium Oxide, 0-0356 0 0446 0-0172 0-064 0-045 0-0809 Chlorine, . 3-079 3-69 1-8129 2-785 3-726 1-949 Phosphoric Acid, 0-4038 0-214 0-7348 1-120 0-240 1-901 Phosphoric Acid iu inorganic combination, . 0-1711 0-0847 0-3502 0-806 0 0715 1-458 * Zeit. physiol. Chem., 1897, 23, p. 521. 44 FLESH FOODS. IDENTIFICATION OF BLOOD IN STAINS, ETC. This belongs rather to the domain of forensic chemistry than to the subjects treated of in the present work, and hence no exhaus- tive description of the methods which have been recommended for the purpose is attempted here. The following details may, how- ever, be found serviceable. Alteration of Dried Blood on Heating.* — When dried blood is heated for an hour at 100° C., it still remains soluble in water, cold saturated solutions of borax, concentrated solutions of potassium cyanide, dilute sodium hydroxide solution, ammonium hydroxide, acidulated alcohol, and glacial acetic acid. After being heated for an hour at 120° C., it becomes insoluble in water, and less soluble in the other liquids, with the exception of sodium hydroxide solution, and acetic acid, in which it dissolves as readily as before. After an hour at 140° to 180° C., it is only slightly soluble in ammonium hydroxide, but more so in sodium hydroxide solution and glacial acetic acid, which must therefore be regarded as the most suitable solvents. Preparation of Hxmin Crystals. — This is generally looked upon as the most characteristic test for blood. By using potassium iodide instead of sodium chloride, Strzyzowski * was able to detect as little as 0 '000025 gramme. In his method a trace of the sub- stance under examination is mixed with a drop of a 0'2 per cent, solution of aqueous potassium iodide on a glass slide, and after the liquid has evaporated, a cover glass is placed over the residue, and a little glacial acetic acid introdriced. The slide is gently heated until the acetic acid commences to boil, and when cold is examined under the microscope. Spectroscopical Examination. — This often furnishes corroborative evidence. The absorption spectra of some of the colouring sub- stances, obtained from blood, are shown on p. 39. Detection of Blood in the Presence of Iron. — It is often impos- sible to obtain ha3min crystals from blood which has become insol- uble from being left in contact with iron. In such cases Gantter f recommends the use of hydrogen peroxide as a reagent. A drop of the solution, or a fragment of the insoluble substance moistened with water, is made feebly alkaline, and a drop of hydrogen per- oxide added. If the slightest trace of blood be present, numerous bubbles of oxygen are liberated, which, in a short time, coalesce into a white scum. Unfortunately, other animal fluids {e.g. pus) behave in a similar * Zeit. annl. Chem., 1898, p. 467. t Ibid., 1895, pp. 159, 160. 45 HiEMOLYMPH AND OXYH^MOCYANIN. manner, so that a positive result is not absolutely conclusive. Still the test is of value as confirmatory evidence. the blood of invehtebrate animals. Hsemolymph.— In worms and the majority of molluscs, the liquid which corresponds to the blood in higher animals, fulfils the functions of blood and lymph, and has hence received th^e name of It is a liquid rich in albuminous sub- stances, and in many cases shows signs of fibrin coagulation, it contains white corpuscles (leucocytes), and in some few instances, red corpuscles, but the latter are rare. Instead of red corpuscles, free oxyhemoglobin is not uiifrequently found in solution, its function being probably of a respiratory nature, and the violet or purple colouring matter in the hemolymph of some invertebrata appears to play a similar part. Oxyheeinocyanin. — In certain arthropoda and molluscs {e.g. the crab, 'oyster, and snail), the hemolytoph has a bright blue colour, due to the presence of an albuminous colouring mattei, which takes the place of the oxyhemoglobin in red blood, but which contains copper instead of iron. This pigment, known as ‘oxy- heemocyanin,’ can be partially separated from the hemolymph by dialysis but it readily redissolves in a dilute solution of sodium chloride. It coagulates at 68° to 69° C., and, like the globulins, can be precipitated by saturating its solution with magnesium sul- phate or sodium chloride. . . When acted upon by acids, it is decomposed into albumin, and a colouring substance which contains a large proportion of copper, and corresponds to hs&matin. When the respiratory oxygen is withdrawn from it in vacuo, or by means of reducing agents, a colourless compound Qmmucyanin) is left, which rapidly becomes blue again on exposure to the air. Neither of these compounds appears to have a very definite absorption spectrum. Other pigments, of the nature of lipochromes, have also been found in hsemolymph of various origin, but these have not been proved to have any definite respiratory functions. CHAPTER III. THE FLESH OF DIFFEEENT ANIMALS. There is no more difficult problem in analytical chemistry than the detection of one kind of flesh when mixed with another. It is true that each has its own characteristic odour, but the substance producing this is probably present in too minute a quantity to be isolated from the flesh or separated from a mixture of such bodies. Ihen, too, the chemical differences which have been recorded by various observers are in most cases incapable of giving reliable date, owing to the variation in the composition of the flesh of different animals of the same species, and the similarity of that of animals of different species. In sonie c^es an examination of the fat of the adipose tissue connected with the muscle or of the fat within the muscular tissue Itself may be of service, as, for instance, in the detection of horse- flesh in meat preparations,* and for that reason the chemical and physical constants of the fat of different animals are given at leno-th in the following pages. Sometimes the flesh contains a considerable proportion of a given constituent, which is either absent altogether or only present in smaller amounts in other kinds of flesh, as, for example, isokrea- tinine in the flesh of the haddock, betaine in the mussel, and gly- cogen in horse flesh. In such cases a quantitative determination of the substance may give an approximate idea of the amount of the original flesh. It is only, however, in the case of horse-flesh that such a method has as yet been worked out wuth any degree of success. C, \ irchow' t made experiments to determine whether there w'as a difference in the amount of soluble extractives in different kinds of flesh. After removing all visible fat, the finely divided flesh was extracted with water at 45° C., the extract boiled, filtered from the coagulated albumin, an aliquot part of the filtrate evapo- rated, and the residue dried and weighed. His results showed that * Cf. p. 141. t Virchow's Archiv, 1881, p, 643. COMPOSITION OF THE FLESH OF DOMESTIC ANIMALS. THE FLESH OF DOMESTIC ANIMALS, 47 No. of Analyses. T-( (N CO r-H ^ 1-4 : ^ 05 05 00 \a 0 rH C5 rH 9 O a Nitro- gen. o ^ p o JO ^ rH r— * 11-13 13-92 05 rH 0 0 1-H iC rH T— ( , 6-70 •11-43 — 0 05 IC « •^^4 Ah , rH 8-98 14-53 13-71 ct tr ■“■'S . a ^ £ 02 o >, eS CO CO CO iO 00 (N 05 CO I-H CO ^ cp C> p cp CO CO C5 61-28 23-70 CO p 0 Ajh C5 C5 rH CO 0 p 01 0 00 r}4 . (N p ^ rH Ah CO 0 cp ^ Ah 0 CO CO 05 W 0 iH 05 0 0 rH (N rH 05 rH p 0 rH rH N.-free Extractives. : : ' 0 »— ( • 0 * 0 0 • : : : ; 50) to • p rH 0 Per Cent. 4* cd 00 l-l Tj4 p 05 XO rH (N 0 00 !>• tH rH C5 00 A' 0 *— 1 p 00 0 CN I-H p 00 r— CD CO 0 to UT5 p 0 5C5 0 rH rti 3 03 2 o C rt ^ rS bo.2 O M h ^ 16-75 20-96 20-71 CO CO xCi Oi 0 !-• (M 18-88 19-86 C5 rH CO rH CO r-4 rH \C p p 4jh 0 rH C5 18-90 23-30 21-70 d IziOJ 03 4» 03 63-05 72-03 76-37 CO ^ 05 CO 0 CO i-* 05 W Qp 00 !>. 53-31 75-99 0 p (N ^ £-*» 05 0 0 CO p C5 A- 05 rj4 CO l>» !>• Condition. very fat, medium, lean, • G 44 ed tS r2 • 0 4^ o3 rf 03 U— 1— « « P 4-a cd 53 « P 03 «-N- (minimum), (maximum), (mean). 13 1 =■ 0 0 uJT 'a 0 £i 03 03 bo s 03 05 f-i 0 W (mean), 74 '20 21 '70 0'46 48 FLESH FOODS, there was no appreciable difference in the total amount of ex- tractives yielded by the muscular fibre of different species, or of different animals of the same species, whatever their age, condition or food. ’ In the case of the ox his mean results were : Ox (healthy). Fat. Lean. Water, . . . . 76-68 76 ‘25 Extractives, . . . 3'73 3-53 ,, calculated on dry substance, . 15 '78 15 '09 (diseased). 77'47 77'61 percent. 3-87 3-82 17-19 17-22 . „ In the description given in this chapter of the varieties of flesh more commonly used as food, a classification into four groups has been adopted for the purpose of convenience : — (1) Domestic animals ; (2) Game and birds ; (3) Vertebrate fish ; (4) luvertebrata. The word ‘ flesh ’ is here chiefly used in its colloquial sense of fat and lean meat. THE FLESH OF DOMESTIC ANIMALS. There is, in general, a marked distinction between the flesh of the common domestic animals and birds and of ‘ game,’ the muscular tissue of the former being of a coarser texture, and undergoing l)utrefactive decomposition more readily than that of the fatten Tliis difference must be chiefly attributed to the difference in food, environment, and habits of life, for when a domestic animal is placed under the same conditions as a wild one its flesh in the course of future generations assumes the finer texture and other characteristics of ‘ game,’ an instance of which is seen in the case of Welsh mountain mutton. The sex of an animal often has an influence on the physical characteristics of its flesh, and, as a rule, the flesh of the female is more tender, but has less flavour, than that of the male. The table on p. 47, compiled from those of Kbnig,* gives the mean results of the analyses of different chemists. The subjoined table on p. 49 by Strohmer f gives an idea of the comparative composition of the chief animals in this group re- garded from another point of view. The average composition of commercial lean meat, freed from bone and all visible fat, is given by Voit as: — Water, 75-9 j pro- teids, 18-4; collagenous substance, 1-6; fat, 0-9 ; extractives, 1-9 ; and ash, 1 -3 per cent. * Nahr. u. Gcnussmiitcl, ii. 110. -f Die Emahrung dcs Menschen, p. 112. CHARACTERISTICS OF BEEF. 49 Fat Calf. Medium Ox. Fat Ox. Fat Lamb. Lean Sheep. Fat Sheep. Lean Pig- Fat Pig. Age of Animal, years. 1 4 4 4 1 14 ? ? Living Wmght, kilos. 258 1232 1419 84 97 107 93 loO Contained per cent. — 12-4 11-4 10 '4 8-1 9-5 7-0 8-3 5-6 Muscular flesh, . . 45-5 47-9 40-2 36-9 37-5 29-8 47-6 37-3 11-0 12-7 25-8 23-7 14-8 32-4 20-0 39'4 Entrails, skin, etc.. 31-1 28-0 23-6 31'3 38-2 30-8 24-1 17-7 Butcher’s refuse, . 37-9 35-2 33-8 40-2 46-7 42-5 26 -3 17'2 Fit for food, . . . 62-1 64-8 66-2 59-8 53-3 57-5 73-7 82-8 BEEF. Characteristics. — The muscular tissue of the ox has a somewhat closer texture than that of the other animals in the preceding table, and retains more of the blood. In certain parts the flesh is nearly free from visible fat, in others the fat is intermingled with the lean, giving a mottled appearance. The connective tissue of an animal in good condition glistens on exposure to the air, and is fairly moist, though no water should exude from it. The proportion of muscular tissue, fat, etc., contained in an ox are shown in the following table of Lawes and Gilbert : — Per cent. Condition. Age. Bones. Muscle. Fat. Skin, etc. Moderately fat, . . . 3 years H‘4 47'9 12'7 28‘0 Fat, 10-4 40-2 25-8 23-6 Influence of Sex. — The flesh of the cow is more tender than that of the ox, but has somewhat less flavour. That of the bull has a rank, strong taste, and in consequence bull-beef may only be exposed for sale in this country with a plain notification as to its nature.* In general it may be stated that the flesh of the male uncastrated animal has a more pronounced taste and smell than that of the female or castrated male. Composition. — According to the analyses of Playfair and Boeck- manu,t beef has the following ultimate composition : — Carbon. Hydrogen. Nitrogen. Oxygen. Asb. V Playfair, . . 51'83 7'57 15-01 21‘37 4-23 Boeckinann, . 51*89 7'59 15'05 21'24 4‘23 * Public Health Act, 1875, § 261. t Liebig,' Organic Chemistry, p. 314. D 50 FLESH FOODS. Almen * found its proximate percentage composition to be Water, 76-76; solid matter, 23-24; proteids, 17-88; fat, 2-24; insoluble salts, 0-65 ; and soluble salts, 0-48. As an instance of the variation in the composition of the flesh from different parts of the same animal, the following results may be quoted from Konig : — Flesh of Fat Per Cent. Per Cent. Calculated on Dry Substance. Ox from Water. Nitrogenous Substances. Fat. Ash. Nitrogenous Substances. Fat. Nitrogen. Neck, . . 73-5 19-5 5-8 1-2 73-58 21 -89 11-77 Shoulder, 50-5 14-5 340 1-0 39-29 68-69 4-68 Digestibaity.—indgmg by the results of artificial digestion experiments, the muscular tissue of the ox is the most digestible of all the kinds of flesh ordinarily eaten, f The Fat. — Beef-fat shows considerable variation in colour according to the age and food of the animals. In young bulls it is whiter than in cows and bullocks, and the fat of animals fed on oil-cake is much yellower than that of animals fed on grass or corn. The fat of certain breeds of cattle, notably those of Jersey and Guernsey, is of a deep yellow colour. In composition beef-fat consists almost entirely of the glycerides of stearic, palmitic, and oleic acids, and is much inore constant in its consistency and composition than the fat of the sheep and pig, although the variation in the fat from different parts of the body is considerable. Lewkowitsch | gives the ratio of stearin to palmitin as about 1 :1, a statement which is borne out by Hehner and Mitchell,§ who found a specimen of fresh beef ‘ stearin ’ (i.e. fat from which the liquid portion had been almost entirely removed, the iodine value being only 2) to contain 50 per cent, of the glyceride of stearic acid, the remainder being, presumably, palmitin. Beef-fat has a characteristic odour, and on crystallization from ether gives fan-shaped bunches of needle-shaped crystals consisting of a mixture of palmitin and stearin. This has been largely employed as a test for the presence of beef-fat in lard. || * Falck, Das Fleisch, p. 346. t Cf. p, 87. X Oils, Fats, and Waxes, 1895, p. 482. § ATialyst, 1896, p. 328. II Of. p. 91. VEAL AND MUTTON. 51 Lcwkowitsch* gives the following Table (see p. 52), by Leopold l\Iayer, of the composition and constants of the fat talcen from different parts of the body of a Hungarian ox, three years old. The iodine value of beef-fat varies, according to different ob- servers, from 35’4 (Filsinger) to 44 (Wilson), and that of the liquid fatty acids from 92 to 92-5 (Wallenstein and Finck). Farnsteiner has found traces of linolic acid and of linolenic acid in ox-tallow (p. 101). VEAL. Characteristics. — The flesh of the calf is of a paler colour and less consistent than beef. It was formerly a general practice to increase the paleness by bleeding the animal before death — a custom which has happily fallen into disuse in this country.! In Germany it is illegal to kill a calf for food at a younger age than ten or twelve days, while a month is the time prescribed in a corresponding Austrian regulation. The muscular tissue of an embryo or of a newly-bom calf is watery, and the fat has a soapy appearance and a distinctive odour. According to Walley f the flesh of a young calf closely resembles that of a dog, and the same authority states that veal is occa- sionally substituted for chicken in certain food pastes. Lawes and Gilbert found a fat calf six months old to have the following percentage composition: bone, I2'4; muscle, 45 5; fat, ILO; skin, etc., 3L1. The general composition of calf’s flesh is given in the table on page 47, and the fat has practically the same chemical character- istics as beef-fat. Veal contains much less iron and alkali salts than beef, but, on the other hand, is richer in connective tissue. According to Staffel J the ash, after deducting the sodium chloride, has the following percentage composition : potassium phosphate, 68-05; sodium phosphate, 5'66 ; calcium phosphate, 3'72; magnesium phosphate, 6'21 ; free phosphoric acid, 15-10; ferric oxide, 0-30 ; and silica, 0-92. MUTTON. Characteristics. — The muscular tissue of the sheep differs from beef in its colour and in being less firm in texture. The flesh of an old ram, however, has a marked colour, and is firm and tough. * Loc. eit., p. 480. t Walley, Meat Inspection, p. 15, i Liebig, Letters on Chemistry, 52 FLESH FOODS. x’ o <) o cn < Ph H 55 W pj W I— ( P o C4 H <1 O m o H 03 a W H O Pi < td o QO ‘3 <1 >1 .1-3 -4-> a 1*1 3 bo -<.Sd ■£s‘° 00 “ “ . C -*-3 . «.£0 3 o° gP •7; tao^J S-5 -So o >».P ® 03**-^ 'S SP *S .S O) 0 Ip 00 03 * ^ _ \i-\ TJH 00 XJ1 (N rH CO CO p p C? t-H rH i) CO kO kO CO CO S fl § p p p p p c 0 ^ T— < CO 0 CO 03 0 «3 0 0 0 0 0 03 CQ (N (N r-i p p CO **5t< O) w o CO CO o 00 CO S 2 T}< 00 0 03 Tj< 'g'3 kO lb lb CO kO lb 03 03 03 03 03 03 1 cS 0 • OJ Tj< 0 cd P< ^ CQ ^ Hehner and Mitchell, - Analyst, 1896, 326- 327. / 1 Schweinitz and Emery, y Jour. Amer. Chem. J Soc., 1896, 174-179. 05 Gladding. Wiley. Teunille. von Eaiuner. Valenta. Dieterich. von Eaiuner. Amthor and Zink. Blehner Value. : : ; : : : ; ; : 93-96 : Saponifica- tion Value, ] Mgnns. KOH. : : : : : . . • : : ; : : : © © 03 © © © © Iodine Value. F. Acids. O O O 05 iH ^ -in CD to to ^ © rH ^ 03 t-“ © © © to © : : : : : : : : : : : Liquid F. Acids. © rn © o 4.^ © l-H © ed 60-68 62-60 63-10 © -n to 00 00 00 © © © © 77-28 86-03 62-65 © © 00 © S © P «P • J_ Is • t- © * p • C3 76-6 Jolidifying Point. F. Acids. o : : : o • . • : : : : ; : : : ; : : © • ck • • • © CO CO i © C<1 CO Melting Point. < 00 ‘o * ^ P © CO C<1 ® (p © 00 p © ijt in © o »b CO eo CO CO : : ; ; ; ; . ; ; : : : : 39-40 L . <» N Ip O CO CO •it' • • : : : tp ^ 05 O t 03 •'n r-f to © © © in CO CO © ; : : ;t : : © CO 40-44 o *c p 02 Gravity. (At 100° C., Water atl6°=l) 0-8607 0-8690 0-8688 : : : ; : : •0-8610-0-8614 0-8696 At 16° C. 0-9424 Description. Mean results, 8 animals. Fat from back, . „ kidney, „ leaf, . Somersetshire pig, 6 months old. Fat from head, . ,, ham, . „ breast, „ flare . „ back, . American pig. Fat from head, . „ intestine, . „ leaf, . American pig. Fat from foot, . „ head, . ,, leaf, . Mixed fat. (Lard), American, . ,, (regarded as highest limit), . German, . American, . Wild boar. 58 FLESH FOODS, tured into sausages, which were supposed to be sold with a declaration as to their nature. Bremer* states that the number of horses slaughtered in the public abattoirs of Prussia were : — In 1891-92, 52,934 ; 1892-93, 52,543 ; 1893-94, 58,306 ; the number in Berlin alone amounting to nearly 10,000 per annum. In Vienna, in 1892, 18,209 horses were killed, the numbers having steadily increased from 943 in 1854, when the first public slaughter-house was established. The price per pound of the flesh has also risen with the number of animals killed. In 1875 it cost 3d. per pound— more than twice what it fetched in 1856 j and its price is said to be still on the increase. _ : Characteristics. — Horse flesh is coarser in texture and darker in colour than beef, and has a more distinctive and less pleasant odour. After standing for some time it develops a peculiar soapy feeling to the touch and a sickly smell, and its surface assumes a characteristic iridescent appearance. The muscular tissue of the horse, like that of the ox, darkens on treatment with alcoholic potassium hydroxide — a reaction which has been employed to dis- tinguish horse flesh from pork. It also develops a peculiar odour on treatment with for- maldehyde (p. 134). The average composition of horse flesh is shown in the table on p. 47, and the methods of detecting it in sausages are described at length on pp. 133-142. 21ie Fat. — Horse fat varies in colour from light yellow to deep orange, and has a consistency similar to that of butter. It con- tains on the average considerably more of the liquid fatty acids than do the animal fats described on the preceding pages. In one case Hchner and Mitchell found a specimen of kidney fat to contain no stearic acid, but by crystallizing a large bulk of another specimen from ether, an insignificant deposit of crystals was obtained which closely resembled the characteristic forms of beef-stearin — a result which pointed to the presence of a trace of stearic acid. Farnsteiner (p. 101) found 9'9 per cent, of linolic acid, but no linolenic acid, in a specimen of horse fat. Amthor and Zink obtained an acetyl value of from 6‘64 to 13 ‘74 with different specimens of fat, by the original method of Be'nedikt and Ulz'er, which, however, as Lewkowitschf has pointed out, is liable to give erroneous results. On the difference in the character of the fat extract ed fromthe muscular tissue, Bremer has based a method of detecting horse flesh in the presence of pork.J * Forschungs Berichte, 1897, p. 1. + Journ. Soc. Chem. Ird., 1897, p. 603. t Cf. p. 141. CONSTANTS OF HORSE FAT. CONSTANTS OF HORSE FAT. 59 Authority. / Amthor l and Zink. R. Friihling, Zeit. ang. Chem., 1896, 352-353. Hehner and Mitchell, Analyst, 1896, 328. Kalmann. Bremer, Forsch. Ber., 1897, 1-8. ^ n • 00 (N 00 , R § Tt< TJl * * * * 05 • uo uo Ti< . . • • ■ 1 CO K> 05 05 05 05 sa CO *43 OO 05 Od 05 05 o <1 P=J CO T-( CO 20 CO Til CO 00 i>- CO ^ CO O ^ rH 00 Til ,-H OC CO 00 05 CO 05 CO I CO 00 "a ■g^l 0> P ■4^ 05 TiH O oo CO 05 Tj< ^ O ^4 ; o3 t=H 05 (M o iO CO * 00 t>» 00 t— 00 CO CO d 03 ip ip O CO (N CO (M tr, ^ CO ^ i£5 CO ^ .2 P o CO CO CO i 1 1 • CO • 4-5 iO Tjl 00 tH ® U O CM 1-t CO Til I* Ph CO CO CO CO UO 03 ip CO Ti< 05 CO . t>* CO CM iP Tii uo 00 111- C» 05 p 'TT s cd pt< P o 03 P a 60 FLESH FOODS. THE FLESH OF WILD ANIMALS AND BIRDS. As was mentioned before (p. 48), the flesh of wild animals differs from that of the animals included in the preceding class in its closer texture and in containing much less fat. But this distinc- tion is largely due to the different conditions under which the animals live. The kind of food given to an animal has a considerable influence on the flavour of the flesh. Where fish has been the chief food the flesh acquires a fishy taste, and there is a marked difference in the flavour of a wild and tame duck. The following are some of the principal average results of the analyses of the flesh of animals in the group. They are taken from the long table given by Konig * : — Per Cent. Per Cent. Calculated on the Dry Substance. Water. Nitrogenous Substances. Fat N.-free Extractives. Ash. Nitrogenous Substances. Fat. Nitrogen Hare, . . 74-16 23-34 1-13 0-19 1-18 90-34 4-37 14-46 Rabbit, . . 66-85 21-47 9-76 0-75 1-17 64-77 29-74 10-84 Deer, . . 75-76 19-77 1-92 1-42 1-13 81-86 7-92 13-10 Hen (lean), 76-22 17-72 1-42 1-27 1-37 82-93 5-97 11-25 „ (fat) . 70-06 18-49 9-34 1-20 0-91 61-76 31-19 9-88 Duck (wild). 70-82 22-65 3-11 2-33 1-09 77-59 10-62 12-92 Goose (fat). 38-02 15-91 45-59 • • • 0-48 38-02 73-55 4-11 Pigeon, . . 75-10 22-14 1-00 0-76 1-00 89-58 4-17 14-23 Schlossberger and von Bibra obtained the subjoined results (see Table, page 61). Bear’s Flesh. — Strohmerf gives the following as the percentage composition of bear’s flesh: — Water, 65T4; nitrogenous sub- stances, 26'37 ; fat, 5 '41 ; and ash, L44. The Fat. — With one or two exceptions, the fat of the animals referred to in the preceding table has been but little examined, and in many cases the constants have been determined only with the fat of one individual. The most complete research on this point is that of Amthor and Zink,J who have determined all the usual constants of the fat of a large number of animals and birds. They found that as a rule * Loc. cit., ii. p. 118. t Ernalirung des Menschen, J Abst. Analyst, 1897, p. 75. 61 WILD ANIMALS AND BIRDS. R hiffh specific gravity of the fat was accompanied by a high point a?d iodine value. The iod^ fata andWv acids decreased on keeping, whilst, on the otner hand in the c&se of many fats, such as that of the stag, dog, an tnd Uar Te acid value increased. The iodine value and, gene- rally, the’ acetyl value* were lower in the fat of than in that of the corresponding wild animals ^ ^ ence was observed in the case of the birds, the fat of the domestic gooLTen, and duck being lard-like, while that of the related wild birds ’was oily. In four cases the fats had marked drying pro Flesh of Water, Nitrogenous Substances. Albumin. Flesh Fibre. Gelatin- yielding. Roe, .... Do., .... Hen, . . . • ■Wild Duck, Pigeon, 74-63 78-30 77-30 71-76 76 00 1- 94 2 30 3- 00 2- 68 4- 50 16-81 18-00 16- 50 17- 68 17-00 0- 50 1- 20 1-23 1-50 perties, three of them becoming quite solid in the course of seven or eight to twelve days when spread in a thin layer on a glass plate. This property was possessed by the fat of the hare, wild rabbit, wild boar, and, in a lesser degree, by that of the blackcock. The fat of the wild boar differed from common lard in having a higher specific gravity, iodine value, and acetyl number, ana especially in the above-mentioned drying property. _ ^ Fox fat differed from that of the cat and dog in its higher iodine value and specific gravity, but more particularly in its high acetyl value.* The principal differences in the fats of the common and wild cats were the higher Eeichert and acetyl numbers and the considerably higher acid values of the latter. Pole-cat fat was quite liquid and had some-what lower constants than the fat of the marten. The fat of the dog and c^ were very similar in appearance to lard, which they also resembled in analytical constants, with the exception of the acetyl value, which was higher. ' , , 1 1 i i Of the different bird-fats examined, that of the blackcock w^as noticeable for its drying properties and high iodine value, ’^en spread on glass it soon set to a varnish, which, how ever, still re- * But cf. note, p. 58 (t). 62 FLESH FOODS. mained sticky. After fourteen days drying was still proceedino-. After ninety-five days the iodine value had fallen to 29-7. The chemical and physical constants of the fat of some of the principal animals of this group, which are used for food, are shown in the subjoined table (page 63). The ‘ Ripening ’ of Game.—\Y\\en game is allowed to hang for sorne time in a whole condition the flesh undergoes an alteration which hiber considered was of a purely chemical nature, although he termed it ‘ acid fermentation.’ The reaction of the flesh becomes strongly acid, the muscular tissue becomes more tender, and after some time traces of hydrogen sulphide are liberated. Eber found that the production of the characteristic flavours of game stood in direct proportion to the amount of hydrogen sulphide or mer- captans set free ; but in his opinion the flavour {haut goiit) was in no way due to the formation of putrefactive compounds. A similar ripening process can be brought about in the flesh of other animals besides game, and indeed is necessary in the case of old cattle, or of bulls. As apparently Eber did not make a bacteriological examination of the flesh before and after ‘ripening,’ his view appears unlikely to be correct, and it is far more probable that the change is brought about by certain species of bacteria. The ^Heeding’ of Game. — When game is packed too closely and subjected to too high a temperature, an alteration rapidly takes place, which is probably, in the main, a chemical change, brought about by bacterial products rather than by the bacteria themselves. Within an hour or two the skin becomes green, the hair loose and easily removed, and the muscle soft and flabby, while bubbles of gas may often be observed within the tissue. The reaction of the flesh is very acid, and considerable quantities of hydrogen sulphide are evolved, so that the flesh has a dis- agreeable odour. Eber* succeeded in imitating the green coloration and acid for- mation by injecting milk of potassium sulphide (0-5 per cent.). The origin, however, of the excess of sulphur compounds in the natural ‘ heating ’ is doubtful, though it is probably due to the rapid permeation of bacterial products from the large intestine. That the alteration is not an ordinary putrefactive process is shown by the facts that no ammonia is produced, and that the change is not progressive, i.e. on removing the causes (the close packing and high temperature) the muscle retains for a consider- able period its consistency and original structure. This condition of the flesh may also occur in the flesh of other * Zeit.f. Fleisch u. Milch Hyg., 1897, vii. p. 208. CONSTANTS OF THE FAT OF WILD ANIMALS WILD ANIMALS AND BIRDS, 63 m O Pi t— I PQ P !z? < Authority. P o .2 B < \ Amthor and / Zink.* L. Drumel.t ++ "O .f4 ^ >* P * S 1,.“ S o,S « r ^ < = : > ■*S > *■13 S ai c. Reichert Value. O O 03 O 03 rH O 1-59 o o 00 ^ o w o ^ 00 cq o CO 03 • • b'^oo ’ O . w |H o o O ' cq c a °. > C Hehner Value. : : : 96-2 t- 03 •P M Tj* S b ! 03 ^ 03 : • ; ; L Saponifica- tion Value = Mgrma. KOH. 199-9 195-6 203 3 6006 to n (jq 03 • O 03 oq rH (?q O o ^ o CO CO :5g C3-^ 03 03 *0 1-H 1— « W la • CO • 03 iH 193-5 200-6 201-6 O 0 f c 0 Iodine Value. F. Acids. « cq 03 CO 00^ cq cq (M w CO 03 I- TOT f.f9 65- 3 66- 1 P CD 70-7 120-0 •4 Fat. ^ ^ iH uo ^ oq (M CM CO (N o iH O 00 . Ci 03 • CO 03 ^ O “P ^ P 00 b 03 kO CO CO C3 CD Ip O 00 U3 00 b CD 81-16 1-21-1 00 Solidifica- tion Point P. Acids. ” C. 46- 48 47- 48 49-50 36-40 37-39 35-36 39-41 31-32 33-34 32 1 CO CO 82-34 31-32 25-28 33 - 34 Melting Point ° C. F. Acids. 60-52 60-53 62-64 44-47 44-46 39-41 48-60 36-6 ) to >- 40.2 ) 38-40 34-40 36-38 o :3 CO 38-40 03 CO CO ,-o 00 b CO CO 38-39 o3 pH 61-62 62-63 62-54 35-40 40-42 35-38 44-46 *P • • r-( A • • cq cogj 36-39 33-40 u tD 15° 0. 0-9670 0-9616 0-9659 03 CO 03 o 0-9342 0-9393 0-861 (at 100°) 00 O 00 cq o t>. (N O CO cq • tH C3 4^ 03 03 ‘03 b bo b ; : •-4 oq 03 b 0-9220 0-9296 Fat from Stag, Fallow Deer, . Roebuck, Hare, Rabbit (tame), . „ (wUd), . »» • • • Goose (from 4 parts of same bird), (wild), . n 11 5 * Duck, „ (Wild), . Turkey, . Blackcock, l» • • • Pigeon, . 64 FLESH FOODS. animals from which the skin has not been removed in the summer. Eber has frequently observed it in the case of horses. According to Fischoeder,* ‘ heated ’ flesh is not allowed to be sold in Germany, although no ill results have been traced with certainty to its use. THE FLESH OF VERTEBRATE FISH. The muscular tissue of fish is generally white, and is less con- sistent than that of land animals. The difference in colour is due to the flesh and the blood retained by it containing so much less haemoglobin. In certain fish, however, such as the salmon, the flesh has a delicate pink tint which Krukenberg attributes to the presence of a colouring matter of the nature of a lipo- chrome. The flesh of tish usually contains a high percentage of water, often as much as from 80 to 85 per cent.; the amount of mineral matter is also usually high, sometimes amounting to nearly 2 per cent. In certain fish special constituents have been found, as, for instance, isokreatinine in the haddock (c/. p. 10). Fish undergo decomposition with extreme readiness, and in many cases the products of decomposition are deadly poisons to the human system. Occasionally, too, the living fish elaborate poisonous substances. These may be of the nature of leucomaines or albuminous toxines, and are probably in some instances due to the condition of the water in which the fish have been living.! The age of carp may be approximately estimated in the follow- ing manner ; — A scale from the side of the fish is cleansed ■with alcohol and held to the light. If only a bright central spot is visible the carp is only one year old. If one ring surrounds the central point the fish is two years old ; if two rings, three years old, and so on. Experiments have shown that the number of rings regularly increases with the age.J The Fat of Fish. — It is mainly to the presence of certain constituents in the fat that the characteristic flavour of different kinds of fish is due. In some fish the liver is the chief source of the fat, as, for instance, in the case of the cod and shark, while the rest of the body contains only a small proportion. In other fish the oil is distributed throughout the body, and is not specially abundant in the liver. The fat is of an oily nature, and as a rule contains a smaller proportion of the compounds of the solid fatty acids than does the t Leilfaden der frah, Flcischbeschau, 1897, p. 199. Of. pp. 219-222. + 2eit. Fleisch u. Milch Eyg., 1897, p. 244. COMPOSITION OF FISH, 65 a o OD o o o o bo d c o o {m Q ft Q C * O O 'o ' OS 03 ' o bo O y= S !■ ■« I c3 i-« O <1> •43 S 2 C aJ C3 rd b0«4H c o o d Q> to © © eo © e<) © CO o i> cJ O © N © pH o a a •4^ © O © O C4 iH tH Tj» © “^ pH pH iH to •§ OQ >> o 'd ©© ©rH © © © O rH © © « J> © O © 1-H UO © © © M « iH Od p 'p 0) ■3 o 'a Q Nitrogenous Substances. © © W Od T*< ■Tj) 1^ ^ © b © ^ © © © © © 90-69 94-22 87-66 © O© © © © oi> © O © w © © © ©-3 i>l>.l>» ©©•?#< ' *a to ^ o S a 0) a ■ a^c ^ a^c oa .cQP^ffli^pq ,i:^qch 03 O "o «4-l GQ » 43 O O pH CO © © O pH © fi © O © © -H © Od © Nitrogenous Substances. © O b-M Od •^ © © © M pH © © '© © © -^ to COpHpHt-t- t- © Tt1 © © ■< O pH pH O O 43 o '. c3 O CO 00 CO 00 ^ T*< W C5 O o 6 © o b ci 3 03 is <0 2 p OC ^,o 3 lO o o CO O © CO -»*« H to£ ^ ^ go -5 ^ ^ ,£3 9 E Loc. cit., ii. p. 121. t Comptcs Bend., 1898, cxxvi. p. 1728. CONSTANTS OF CERTAIN FISH OILS. 66 FLESH FOODS, Authority. Fahrion.* t 1 Kremel.* jLewkowitsch.* Mitchell. + Lewkowitsch. § Lewkowitech. § H. Bull. II Lewkowitsch. § Fahrion. t Mitchell. + H. Bull. II Acid Value. ^ o ^ ^ (M 0-62 to 28-67 (K) 7-6 : : 00 CO : 00 o * b i-t rH 1-8 40-2 0) o .C-3 \p Od w ^ . »o ^ 1 o ^ 8-86 94-7 86-9 97-26 Saponifi- cation Value = Mfcnns. KOH. 6-061 ^ ^ A * _g 00 ti^ CO 1-H 1— 1 N^t^ 8-881 185-4 Ip o b ^ : rH 170-9 184-8 lodineValiia. F. Acids. : CO : : • • • • • Fat. 193-2 191-7 123 to 141 (K) 137-6 (N O eo kA 136-0 114-6 138-6 133-1 131- 0 132- 7 Solidifi- cation Point, F. Acids, •c. CO w .^xei CO -S « (N^rH : : Melting Point, •0. F. Acids. 00 O • Herring (Japanese), ,, (English), . d s • ^ o o o 2b (M o> CO Oi CO 00 oo CO p4 rd ^ S °0_J ^ »-'T3 of2.2 te ►4 |^<=- "O oTpS* s S S ea oo ^ § l-S PQ^;z; ♦ 4-<-»- COMPOSITION OF INVEETEBRATA. 67 fat of land animals.* It is mainly composed of glycerides of various unsaturated acids. The liver-oils usually contain certain bile products, which give rise to characteristic colour reactions with acids and alkalies. A considerable proportion of unsaponifiable matter, principally cholesterin, is also a usual constituent. With the exception of cod-liver oil, the fish fats have been but little studied, and our knowledge of their physical and chemical characteristics is therefore limited. Hehner and Mitchell t ka,ve found that from marine animal oils cod-liver, cod, shark, whale — compounds can be obtained which have many similarities with those prepared in the same way from linseed oil, though they have not the same drying capacity. For a full description of the nature of cod-liver oil and the methods of detecting its adulteration, reference must be made to works dealing specially with the examination of fats and oils. The previous table (page 66) gives some of the constants which have been obtained with fats of this class. THE FLESH OF INVERTEBRATE ANIMALS. The flesh of invertebrate animals does not present any marked difference in structure to that of other animals. In chemical com- position it differs, as a rule, from that of vertebrate animals in con- taining more water, nitrogen-free extractives and ash, and less fat. According to Bolland, the acidity of Crustacea, calculated on the original substance, varies from 0’038 to 0'258 percent. Konig I gives the following percentage composition of some of the members of this group : — Ifitro- N.-free Extrac- tives. Calculated on the Dry Substance. Water. genous Sub- stances. Fat. Ash. Nitro- genous Sub- stances. Fat. Nitro- gen. Oyster, Flesh, 80-6 9-04 2-04 6-44 1-96 46-41 10-47 7-43 ,, Liquid, . 95-76 1-42 0-03 0-70 2-09 33-49 0-71 5-36 ,, Flesh and Liquid, 87-30 5-95 1-15 3-57 2-03 46-85 9-06 7-50 Mussel, 84-16 8-69 1-12 4-12 1-91 54-86 7-07 8-78 Lobster, 81-84 14-49 1-84 0-12 1-71 79-80 10-13 12-77 Crab, . 79-97 15-80 1-54 0-75 1-94 78-87 7-69 12-62 * Excluding the liquid fats extracted from the feet, such as neatsfoot oil, etc. t Analyst, 1898, p. 317, J Loc.cit., ii. p. 130. 68 FLESH FOODS. The following representative analyses are taken from A. Bolland’s table * : — Kltro- genous Sub- stances. Drj- Substance. Water. Fat. N.-free Extrac- tives. Ash. Nitro- genous Sub- stances. Fat. N.-free Extrac- tives. Ash. Crab, 76-5 16-89 0-87 6-76 0-99 67-60 3-69 24-60 4-21 Cockle, 92-0 4-16 0-29 2-32 1-23 52-00 3-67 29-00 16-33 Oyster, 80-5 8-70 1-43 7-33 2-04 44-60 7-32 37-61 10-47 Mussel, Burgundy 82-2 11-26 1-21 4-04 1-30 63-20 6-82 22-68 7-30 Snail, Weinberg 79-3 16-10 1-08 1-97 1-56 77-88 5-20 9-62 7-60 Snail, 80-5 16-34 1-38 0-46 1-33 83-78 7-10 2-32 6-80 A. Chatin and A. Muntz t have determined the amount of phos- phorus ill different varieties of oysters. In 100 parts of the dry flesh they found 1'836 parts in French oysters, and 2'082 parts in Portuguese oysters. A Portuguese oyster of medium size con- tained 0‘032 gramme, and a similar French oyster 0’02 gramme of phosphorus, which was present in combination with organic substances. Iron was also present. Green Oysters. — From the recent researches of Boyce and Herdman J there appear to be several kinds of greenness in oysters. In some varieties, such as the Marennes oysters and those from rivers on the Essex coast, the green colour is a normal and healthy condition, and is to be attributed to the presence of a pigment termed ‘ marennin ’ and not to an excess of copper. This confirms Kay Lankester’s conclusions, who found that the copper in green Marennes oysters was not greater than that normally present in the hamocyanin of the blood of colourless oysters. The average amount of copper found by Kohn in his analyses for Herdman and Boyce in different varieties (including those of Marennes) was 0’006 grain. In some kinds of greenness, however, there is undoubtedly a larger proportion of copper than this normal quantity. In certain American kinds, and in oysters from Falmouth, Herdman and Boyce found patches of green on the mantle and in the heart, * Comptes Hcnd., 1898, exxvi. p. 1728. t Compt. Rend., 1895, p. 1095. t Proc. Roy. Soc., 1897, Ixii. p. 30, and 1899, Ixiv. p. 239. GREEN OYSTERS. 69 which were derived from an excess of copper in the blood leuco- cytes. This they attributed to a diseased condition of the blood which they term ‘ green leucocytis.’ The quantity of copper m the o-reen leucocytes varied considerably, some giving a marked brown coloration with potassium ferrocyanide, while others gave only a faint reaction. Occasionally iron was also found. In the case of the Falmouth oysters, part of the excess of copper was mechanically attached to the body, probably as basic carbonate. Attempts to produce the greenness artificially by feeding oysters with dilute solutions of copper or iron salts were unsuccessful. CHAPTER IV. THE EXAMINATION OF FLESH. The absolute value of flesh as food, apart from the relative value which depends on the nature of the animal from which it was taken or its position in the animal, is largely based (1) on its physical external characteristics, such as colour, consistency, etc. ; (2) on the proportion of fat; and (3) on its taste and odour. COLOUR. The normal colour of sound flesh varies with its origin, ranging from white, as in the case of many fish, to dark pui'jjle-red, as in horse flesh. The colour being largely dependent on the amount of hsemoglobin in the flesh, an approximate ratio may often be observed between the colour and the amount of iron (chiefly derived from the hsemoglobin) in the ash, left on calcining the flesh. Abnormal Colorations of Flesh. Melanoais. — Morot * describes a case in which the flesh of a calf three months old was found to contain numberless small black specks distributed throughout the body. Sometimes this is only local, and not, as in this instance, general. The black pig- ment is probably a derivative of hsemoglobin. In Germany such flesh is sold at a low price by the Freibank (p. 215). White Flesh. — This is found normally in certain full-grown foreign animals. Occasionally it may happen that the flesh of a cow or ox does not acquire the usual amount of hsemo- globin and has the appearance of veal. Faucon f records a case of the kind in which the muscular tissue of a cow four years old had all the appearance of a calf’s flesh, differing only in the larger size of the muscular fibres and in its greater dryness. White flesh is * Zeit. Fleisch u. Milch Hyg., 1898, p. 501. t Ibid., 1898, p. 34. ABNOKMAL COLOUKS IN FLESH. 71 found in certain diseases, such as the anaemia of dropsy, and is probably caused by an insufficient oxidation of the blood. Yellow Colour. — This is sometimes produced by the food given to the animal. In disease it is due to biliary compounds being absorbed and retained by the flesh. Brown Flesh Xantosis'). — An instance of this is described by Goltz, in which flesh had a brown coloration due to the presence of granules of a yellowish-brown pigment between the fibres. Dark Purple. — This may indicate that an animal has suffered from acute fever, and it is met with in animals that have died of rinderpest or tuberculosis. It may also be due to the animal having died a natural death, so that the blood has been retained in the body, or to insufficient bleeding after death, due to weak action of the heart. Dark Reddish-Brown. — This is due to imperfect oxidation of the blood. It is observed in the case of animals which have been droAvned or sufibcated in smoke (COg poisoning). There is also often considerable discoloration in the flesh of animals which have been hunted or over-driven. Scarlet. — This is but seldom met with. It indicates carbon monoxide poisoning, and is sometimes a result of arsenic poisoning (Walley). Diffused Redness. — This is due to the difiusion of haemoglobin, and is often seen in meat which has been frozen. It is also found in cases of blood-poisoning. Iridescence. — This is a normal characteristic of horse flesh. In other animals it occurs as the result of certain diseases of the blood. Green or Violet Hue. — This may be due to the commencement of putrefaction, or to the diffusion of vegetable colouring matter through the membrane of the stomach after death (Walley). (See also Green Oysters, p. 68.) Colorations due to the Direct Action of Bacteria, These are referred to under the heading of ‘ Chromogenic Bacteria on Flesh,’ p. 270, Artificial Coloration of Flesh. Kellermann* has recently detected saffron in a sample of so-called smoked pork. The connective tissue was very yellow, while the muscle had the colour of ordinary flesh. It had not the usual smell of smoked flesh. On treatment with alcohol an * Zeit.f. Vntersmh. Nahr. Genussm., 1898, p. 247. 72 FLESH FOODS. intensely yellow solution was obtained, which, on evaporation, left a residue giving a violet coloration with sulphuric acid. An account of the various substances used to colour sausages and meat preparations, and the means of detecting them, is given in a subsequent chapter.* The ‘Flesh Juice’ (‘Roseline’) of Adamczyk, Berlin, consists of red carmine lake in ammoniacal water. UNSOUND FLESH. In this covmtry the inspectors condemn the flesh of animals which have died from natural causes, or as the result of an accident, as well as of those which have suffered from certain diseases, such as pleuro-pneumonia, puerperal fever, etc. Meat which is tainted with chemical substances, such as phenol, or in a state of putre- faction, or infected with animal parasites, such as liver flukes or hydatids, is also obviously rejected. To distinguish the meat of diseased animals cannot, as yet, be done with any certainty by chemical methods, and it requires considerable practice to form a correct judgment of the character of flesh by its appearance. The bacteriological methods of examina- tion are described in Chap. XIII. General Characteristics of Soimd Flesh. — A.ccording to Letheby,t sound fresh meat has the following general charac- teristics:— 1. The colour is neither very pale nor dark purple. 2. It has a marbled appearance, due to the presence of small veins of fat distributed throughout the muscle. 3. It is firm and elastic to the touch, and not sodden or flabby, and scarcely moistens the finger. 4. It is free from objectionable odour. 5. It does not become wet on standing for a day or so, but, on the contrary, gets drier. 6. It does not lose more than 70 to 74 per cent, in weight when dried at 100° C., whereas bad meat often loses more than 80 per cent. 7. It does not shrink much in cooking. Chemical Tests for Unsound Flesh. Apart from alterations in the appearance of the parts locally affected with the disease, it is probable that chemical alterations also occur in the flesh through the products of the bacterial action permeating the muscular tissue of the living animal. So far the only attempt to differentiate diseased from healthy flesh * Cf. p. 142. t On Foods, p. 210. EBER’S HYDROGEN SULPHIDE TEST. 73 on these lines is that of Professor Eber, who was still working on the subject at the time of his death.* His test is based on the fact that in the case of diseased animals, especially those suffering from tuberculosis, there is often a considerable increase in the amount of readily decompos- able sulphur compounds in the flesh, which can he approxi- mately measured by noting the relative amount of hydrogen sulphide (or mercaptans) evolved on treating the flesh with dilute acid. Although hydrogen sulphide is often one of the products of putrefactive decomposition, its presence does not necessarily denote putrefaction. Thus traces of it are normally present in the free state in all old flesh, of which the reaction is still acid, and considerable quantities are evolved during the ‘ heating ’ {‘verhitzein^) of game.f That the volatile sulphur products of pathogenic bacteria may be rapidly diffused throughout the body is shown by the fact that the carcasses of pigs killed on account of swine erysipelas turn green after the lapse of a very short time (thirty minutes), and emit an unpleasant odour; and, as the flesh still has an acid reaction, putrefaction is here out of the question. The muscles, kidneys, and lymph-glands of healthy recently- killed animals evolve hydrogen sulphide when heated in a test- tube on the water-bath, the gas being probably derived from the decomposition of proteid matter; but Eber could not notice any difference in the quantities thus yielded by healthy compared with diseased flesh. The more limited decomposition brought about by the action of dilute sulphuric acid gave more promising results, which Eber was intending to confirm and extend. Eber’s Hydrogen Sulphide Test.j; — From 10 to 25 grammes of the finely divided substance are mixed with 50 grammes of dilute sulphuric acid, (1 ; 10) in an Erlenmeyer flask, in the neck of which is fixed, by means of a loose plug of cotton-wool, a strip of filter-paper previously soaked in a 10 per cent, solution of lead nitrate. The flask is kept in the dark for twenty-four hours in a spot to which there is free access of air, without a draught, at a temperature which may vary from 12° to 18° C., without influ- encing the results. At the end of the time the strip is gummed in a book, and after the lapse of thirty minutes compared with a standard scale of strips. * ^Y, Eber, born 1863, died June 1898. t Cf. p. 62. + Zeit. Fleisch u. Milch Eyg., 1897, vii. pp. 207-211, 227-231 ; and viii. pp. 41-46. 74 FLESH FOODS. The colour of the strip will vary from faint brown (mrely yellow) to black, the lower part being the most intense. The colour scale,* of which the relative shades are shown in the frontispiece, is an arbitrary one, and the absolute value of each colour was not definitely determined by Eber. Preliminary experiments, with a solution of potassium sulphide yielding an accurately determined amount of hydrogen sulphide, indicated that the lowest colour in the scale No. 1 corresponded to 0'002 milligramme of hydrogen sulphide, while No. 8 (black) was first attained with O'Ol milligramme. By this method Eber found that the mean results obtained with the flesh of different kinds of animals were, as a rule, some- what higher in cases of tuberculosis (viz., 4*6 as against 3 ’5), whilst the tests with the ileo-lumbar glands often showed a con- siderable difference, as is seen in the following figures : — i. Healthy, . .130 samples. 100 negative, mean 0'2 ii. Local tuberculosis, 44 „ 8 „ „ P6 iii. General tuberculosis, 36 „ 3 „ „ 2‘7 The results given by the kidneys were invariably high (6 to 7), and no difference could be found between those of healthy and of diseased animals. As these figures were obtained without the precaution of exclud- ing light, which, as was subsequently found, tends to lower the value, it was Ebor’s intention to repeat the tests. Much more work is required on the subject before this test can be regarded as having passed the experimental stage, but it indi- cates a starting-point for fresh departures, and has possible appli- cations in other directions. Thus it may be found to serve as a measure of the haut goM of game,t and may be employed to eluci date the progress of the changes which occur in the putrefaction of flesh. The Ptomaines formed during Putrefaction. — The methods of isolating the basic alkaloidal products formed during the decomposition of flesh by saprophytic bacteria, and the charac- teristics of individual ptomaines, are described in Chap. XIV., p. 298. The Keaction towards Litmus Paper. — A slice is cut from the meat and pressed against a piece of moistened litmus paper. After ten minutes the paper is removed and compared, on a * The original colour scale may be obtained from R. Schotz, Luisenstrasse 36, Berlin, N.W. t Cf. p. 62. 75 CHEMICAL TESTS FOR UNSOUND FLESH, white surface, with a piece of the original litmus paper similarly moistened. „ i -v j As a o'eueral rule, flesh becomes acid soon after death, and con- tinues so until sufficient ammonia is produced during the progress of putrefaction to render it alkaline.* _ According to Augst,f in cases of acute pneumonia, or other diseases causing shortness of breath, the flesh only assumes the normal acid reaction some twenty-four hours after death, and is alkaline until then. _ HartensteinI records a similar phenomenon in the case ot a cow which had been killed after suffering for five days from colic. The flesh had a marked alkaline reaction four hours after death, and it was not until the next day that it became acid. . 1 • Occasionally the result of the litmus test is a colour inter- mediate between the red and blue. This ‘ amphoteric reaction occurs most frequently in the muscles of animals which have not been cut up, such as birds and fish. The alkaline reaction is also obtained with certain organs of the body in a fresh condition, as, for example, the spleen. Pickled flesh and smoked ham are also, as a rule, strongly alkaline. Eber’s Test for Putrefaction. — To detect incipient putrefaction, Eber§ recommended the use of a reagent, composed of hydro- chloric acid, 1 part ; alcohol, 3 parts ; and ether, 1 part. A glass rod is moistened with this and brought near the meat, from which, if putrefaction has commenced, fumes of ammonium chloride are often produced. In order to avoid the chance of error, due to the fuming of the hydrochloric acid itself, a few c.c. of the reagent are introduced into a stoppered cylinder, which is shaken so as to moisten its sides, and a fragment of the meat introduced on the end of a wire. The intensity of the cloud of ammonium chloride is not pro- portional to the odour of the flesh, for in some instances putrefac- tion may proceed without the evolution of malodorous substances, and in others these may only become evident on boiling the flesh. This is noticeable in the case of salt fish, in which there may possibly be a combination between the volatile bad-smelling com- pounds and the salt. Sometimes Eber’s reagent gives negative results when putre- faction has commenced, owing to the formation of acid substances, instead of or in excess of the ammonia. This is especially the case with liver and with game. * Cf. p. 19. t Deutsch. Tierdrzt, Wochensch., 1897, p. 37., X Zeit. Fleisehu. Milch Hyg., 1898, p. 68. § Arch. Wissensch. praic. Thierheilk., 1893, xviii., and 1894, xix. p. 81. 76 FLESH FOODS. Eber classified the results of this test in the following scheme ; — I. No cloud of NH4CI (absence of ordinary (alkaline) putrefaction). Reactvm , . ter' }{a) with bad odour, (6) without „ i. with H,S. ii. without HgS. Reaction flesh, II. Cloud (Putrefaction proper). Acid, Amphoteric, Alkaline, )(a) with bad odour, {b) without „ i. with HgS. ii. without HoS. TREATMENT OF MEAT WITH ANTISEPTICS. It is no uncommon practice for butchers to treat meat which has been kept too long with various chemical solutions in order to retard or disguise the commencement of decomposition. Of these reagents the least objectionable is a dilute solution of potassium permanganate, which removes the odour from meat slightly tainted on the surface, but is incapable of disguising deep- seated decomposition. Many of the preservative solutions contain calcium or sodium sulphites or bisulphites as a chief constituent. The salts of sul- phurous acid have not only an antiseptic action, but possess the property of restoring the colour of fiesh which has become brown or grey through exposure to the air. The action of sulphurous acid on the meat fibres, and the methods of detecting it, are referred to on p. 121. Borax and boric acid are also frequently used for this purpose. L. Baillet records the results of experiments in which joints of mutton were steeped for a month in a solution of borax. The meat had nearly its normal red aspect, but the borax had pene- trated a long way into the flesh, and could readily be detected by turmeric paper (see also p. 119). According to de Cyon of St Petersburg, meat treated with a solu- tion of boric acid acquires a disagreeable appearance and flavour. The use of salicylic acid or formaldehyde, which are said to be employed for ‘ doctoring ’ meat, cannot be very general on account of their other effects (pp. 122-123). As meat which has thus been treated is often in a state of arrested decomposition, the following tests will often be service- able in detecting the fraud. * Traiti de V Inspection dcs Viandes, p. 523. 77 ‘BLOWN meat’ — CONSISTENCY OF FLESH. 1. 2. 3. 4. 5. 124). General appearance and physical characteristics, such as excess of moisture and want of firmness 3 meat which has been kept too long readily tears, and does not cut evenly. The appearance and acid value of the fat (c/. p. 9o). The reaction of the meat-juice towards litmus and turmeric paper (p. 74). / n The microscopical appearance of the fibres (p. 11 7). The chemical identification of definite preservatives (pp. lio ‘BLOWN’ MEAT. With the object of imparting a better appearance, meat is soine- times ‘ blown ’ by butchers. This process consists in inflating the loose cellular tissue by means of bellows, or usually with the breath through a blow-pipe, and then blowing melted fat over the parts. In Germany this disgusting practice is common in the case of calves and sheep, but is less frequently met with in beef. In this country, according to 0. Andrews, veal and lamb are occasion- ally ‘blown.’ The blown-out parts appear larger, and have a shiny surface, while the muscle feels spongy and crackles under the pressure ^ of the finger. Small air-bubbles may frequently be observed within the tissue. Lungs which have thus been ‘ blown ’ have rounded edges, and contain isolated air-bubbles. CONSISTENCY OF FLESH. The consistency of meat is a valuable criterion of its soundness. Good meat is firm to the touch, while unsound flesh is frequently flabby and exudes moisture. Coarse-grained meat, which cannot be cut evenly and regularly, is inferior to fine-grained. The nature of ‘ grain ’ depends (1) On the age of the animal, the fibres being finer in the case of young animals; (2) On the race of animals and nature of their feeding ; and (3) On the sex of the animal — the cow, for example, having flesh of finer fibre than the bull. Determination of the Degree of Toughness.— Lehmann f has devised an ingenious apparatus for determining the degree of tough- ness of different food products. This consists of a balance with arms of different lengths, the shorter being constructed on the principle of a pair of scissors with one of the blades fixed. The weights are placed in the pan of the longer arm, and the force required to cut through a layer of the substance 1 cm. thick is expressed in grammes. * Fischocder, f Zeit, Fleish u. Milch 3yg., 1898, viii. pp. 32-33. 78 FLESH FOODS. "With this apparatus Lehmann found that the skin muscle of beef is two and a half times as tough as the fillet, owing to the greater proportion of the white (collagenous) fibres of connective tissue in the former, and of elastic fibres in the latter. Colla- genous fibres (sinews) required 1040 grammes, whilst elastic tissue required only 580 grammes for complete division. Hence, flesh which contains much collagenous tissue becomes more tender on boiling, whereas that containing but little remains practically the same. For instance : — Raw, Boiled, Fillet of beef, .... grammes. grammes. 83-4 84-0 Skin muscle of beef (Hautmusket), 236-4 88-8 following values were also obtained with different parts of the r in the raw and cooked state : — Raw, Boiled, Heart, grammes. grammes. 104 88 Tongue (Hyoglossus), • • • • 64 Liver, ox, . 42 8 „ calf, .... 35 6-6 Kidneys, ..... 40 24 Brain, ..... 7-0 2-4 It is interesting to note that game, on hanging, loses in a few days 25 per cent, of its toughness. THE ODOHE OF FLESH. This is best observed on boiling fragments of the flesh with water, and in some cases by mixing the flesh with dilute sulphuric acid, distilling about a fourth part of the liquid, and noting the smell of the distillate. It may be : — (i.) The normal odour characteristic of each kind of animal, (ii.) The characteristic odour intensified to a very unpleasant extent, in the case of the flesh of uncastrated male animals. This is more marked with the flesh of the he-goat and boar than with that of the ram and bull, (iii.) An abnormal odour, due to the substances (fish, for example) eaten by the animal. (iv.) An odour due to chemical alteration or decomposition, as, for instance, that of the volatile products formed during the ‘ heating ’ of giime, or the putrefaction of flesh, (v.) An odour of foreign substances — phenol, chloride of lime, etc. DETEKMINATION OF WATER AND ASH. 79 ANALYTICAL METHODS. Determination of Water. — From 5 to 10 grammes of the finely divided flesh are dried in an air bath maintained at 105°-110 C. until the weight is constant. If the substance is readily oxidizable it must be dried in vacuo, or approximate results may be rapidly obtained by the following method, used by C. Parsons * for sensitive organic bodies, in which the action of atmospheric oxygen is excluded during the drying A neutral mineral oil with a high flash test and boiling point is heated at 250° F. until its weight becomes constant. A basin con- taining some of the oil is weighed, heated at 240° F. for some minutes, a few thin pieces of the meat (previously weighed) added, and the heating continued until all effervescence ceases. The loss in weight of the basin containing the oil and the meat gives the amount of water expelled. Abnormal Moisture. — Walley f gives a summary of the various causes leading to an excess of water in flesh. These are (1) Albu- minous efiusion, as in ‘ turnip braxy ’ in sheep (c/. p. 53), due to enzymic action in the cells of the living animal ; (2) Effusion of serum or hydrsemia, as in the ‘ water-braxy ’ of sheep. This is also found in diseases with inflammatory symptoms, such as erysipelas, and may originate from irritation set up by parasites (cysticerci). Effusion of serum occurs in meat which has been thawed after freezing. (3) Lymph effusion, either local or diffused, arising from inflammation or other disease. (4) Effusion of blood, either local or general, caused by violence or disease. (5) Effusion of urine, which is necessarily local. Determination of Mineral Matter (Ash). — The residue left from the determination of water is ignited in a covered platinum dish, preferably in a muffle-furnace. Iron, Calcium, and Magnesium. — The ash is dissolved in dilute hydrochloric acid, and the iron precipitated with ammonium acetate, the calcium with ammonium oxalate, and the magnesium with sodium phosphate. Sodium and Potassium. — Warden and Bose J determine these metals in the following manner ; — The soluble ash is dissolved in water, barium chloride, ammonium chloride, and ammonia added, and the liquid heated and filtered. The filtrate is mixed with ammonium carbonate and ammonium oxalate, heated and filtered. The filtrate and washings are evaporated to dryness, the ammonium salts removed by gentle ignition, water added to the residue, and the insoluble matter filtered off. The filtrate is mixed with a few * Journ. Amer. Chem. Soc., 1897, p. 388. t Loc. dt., p. 33. t Chcm. News, 1890, Ixi. p. 291. 80 FLESH FOODS. drops of hydrochloric acid, and evaporated to dryness with an excess of platinum chloride. The residue of double chlorides thus obtained is treated with alcohol in the usual manner, but the insoluble potassium compound, instead of being weighed, is ignited at a low temperature, the residue exhausted with boiliug ’ water, and the resulting solution of potassium chloride titrated with standard silver nitrate. The alcoholic solution containing the excess of platinum chloride and the platinum sodium cliloride is evaporated to dryness in a platinum basin, sufficient ammonium chloride solution added to combine with all the platinum, the mixture evaporated to dryness, and the residue cautiously ignited. The final residue is extracted with hot water, and this solution also titrated with silver nitrate. From the results of the two titrations the respective amounts of potassium and sodium are calculated. Estimation of Sulphur. — The finely divided flesh is placed in a large silver or nickel dish, and covered with about twice its weight of sodium carbonate, on which is laid a piece of sodium hydroxide about half the weight of the carbonate. The dish is moved slowly over a small flame until all evolution of gas has ceased, and a half fused mass is obtained. Finely powdered sodium peroxide is then dusted over in successive small quantities until the carbon has been completely burned away. When cold the mass is treated with water, the solution filtered, hydrochloric acid containing bromine added, and the liquid boiled until free from odour. The sulphate is then precipitated with barium chloride in the usual manner.* Estimation of Chlorine. — A weighed quantity of the flesh is calcined with calcium nitrate, the residue dissolved in hot dilute nitric acid, and the chlorine determined either gravimetrically or volumetrically. Estimation of Phosphoric Acid.— J. Katz f lays stress on the importance of determining the amount of this constituent. He states that the phosphoric acid which can bo extracted from the flesh with water belongs to the phosphates, wffiilst that obtained from substances soluble in alcohol is a constituent of the lecithin. The substances insoluble in both solvents contain the phosphorus of the nucleins (see p. 21). Estimation of the Total Kitrogea — The total nitrogen may be determined either by combustion with soda-lime, or, more readily, by modifications of Kjeldahl’s process. In ordinary cases correct results are obtained by the Gunning * A. von Asboth, Chem.. Zdt., 1895, xx. p. 2040 ; C. Glaser, Joum, Amer. Chem. Soe., 1898, xx. p. 130. ESTIMATION OF SOLUBLE CONSTITUENTS. 81 modification, in which the substance is oxidized with boiling sul- phuric acid, to which potassium bisulphate and a drop of metallic mercury are added after frothing has ceased. ^ _ When, however, nitrates are present in any quantity, as in_ tne case of ineat which has been pickled in a solution containing nitre, lodlbauer’s modification should be employed. In this 2 grammes of salicylic acid (or phenol) are previously dissolved in the sul- phuric acid, and 1 or 2 grammes of zinc dust and a little mercury introduced into the flask before the heat is applied. Dyer* recommends the rapid introduction of the oxidizing agents, in order to avoid loss through the formation of lower oxides of nitrogen. . Rivike and Bailhachef made experiments with various sub- stances with the object of shortening the time required for the oxidation. They found sodium pyrophosphate, prepared by calcining the ordinary phosphate, the most suitable substance for raising the temperature of the sulphuric acid a-nd accelerating its action. At the same time a much smaller quantity (2 grammes) was required than in the case of potassium bisulphate. The corn- parative table published in the original paper shows that this modification gives accurate results with horn, dried blood, and flesh. ~rr . . The Soluble Extract and Residual Muscular Fibre.— Konig adopts the following method of determining the soluble substances in flesh : — About 50 grammes of the flesh, freed as completely as possible from fat, are repeatedly extracted with cold water, the united extracts filtered, the filtrate made up to definite volume, and aliquot portions taken for the subjoined estimations : (i.) Total Soluble Matter. — An aliquot portion is evaporated in a platinum basin and dried at 100°-105 C. (ii.) Ash. — The residue left on evaporation of ignited in a covered platinum basin About 94 per cent, of the total mineral flesh goes into solution. (iii.) Total Soluble Nitrogen. — An aliquot portion is evaporated in a tinfoil basin, the residue (with the tin-foil) intro- duced into a Kjeldahl flask, and the nitrogen determined in the usual way. (iv.) Soluble Albumin. — An aliquot portion is boiled, the coagulated albumin filtered off, and the amount of nitrogen remaining in the filtrate determined and de- ducted from the total nitrogen. The difference, multi- plied by 6'3, gives the quantity of albumin. * Analyst, 1895, p. 242. t Bull. Soc. Chim., 1896, xvi. pp. 806-811 : Analyst, 1396, p. 267. F the water is and weighed, matter in the 82 FLESH FOODS. Collagene. — On treating flesh with boiling water instead of cold, or at 40° C., no albumin is dissolved, but gelatin derived from the connective tissue passes into solution. A weighed quantity of the flesh is first extracted with cold water, as above, and then with boiling water, which dissolves the collagene, leaving behind the fat and fibre. The amount of collagene is determined by evaporating an aliquot part of the hot water extract and drying the residue at 100°-105°. Muscular Fibre. — The residue left from the successive cold and hot water extractions is collected on counterpoised filter-papei*s, washed with hot water, then with warm alcohol, to remove the water, and finally extracted with ether, which removes nearly all the fat. It is then dried at 105°-110° C. and weighed. The amount of the constituents of flesh soluble in water varies between 4 and 8 per cent., the mean, including albumin and gelatin, being from 6 to 6 '6 per cent. Substances Soluble in Alcohol. — The amount of these is deter- mined in the same manner as the aqueous extract. According to Kbnig they consist of flesh bases, non-nitrogenous extractives and salts, and vary in quantity from 1 '5 to 3 per cent., the mean being about 2 per cent. The strength of the alcohol used is 80-90 per cent. Nature of the Soluble Nitrogenous Substances.— Salkowski * treats the flesh with water at a temperature not exceeding 30° C., in order to prevent as completely as possible the gelatin dis- solving. He finds that under these circumstances 2 2 '6 per cent, of the total nitrogen of the flesh is dissolved, the solution con- taining coagulable albumin, albumoses, peptones, the flesh bases, and Siegfried’s carno-phosphoric acid. Determination of Phospho-Camic Acid.f — After precipitating the phosphoric acid from the extract by means of calcium chloride and ammonium hydroxide, the camo-phosphoric acid is precipitated with ferric chloride. The precipitate, which also contains some ferric hydroxide, is dried, and the nitrogen it contains deter- mined by Kjeldahl’s process. The quantity of nitrogen multiplied by 6‘124 gives the camo-phosphoric acid. Determination of the Amide Nitrogen. — Of the numerous methods which have been proposed for the estimation of amide nitrogen in the presence of proteids, J. W. Mallet J has found precipitation of the proteids, with phosphotungstic acid supple- mented in some cases by precipitation with tannin, to give the most satisfactory results. * Forschungs Bcrichte, 1897, p. 22. t Balke and Ide, Zeit. Physiol,, 1896, p. 330. X Bull. 54, U.S.A, Department of Agriculture, abst. Analyst, 1899, p. 328. DETERMINATION OF AMIDE NITROGEN AND FAT. 83 For the analysis of raw or cooked meat he triturates a weighed quantity with sharp-edged sand (previously ignited) or with hard glass, so as to thoroughly subdivide the tissue. Two aliquot parts" of this pulp are taken, of which one is used for the deter- mination of the total nitrogen. The other is digested with cold water (to avoid formation of gelatin) so long as soluble matter is removed to any extent. By this treatment kreatinine and sar- cosine are readily dissolved ; kreatine fairly readily ; but xanthine, hypoxanthine (1 ; 300) and carnine (1 iSTi) are less soluble. The filtrate is rendered slightly acid with acetic acid, heated to about 99° C., and filtered from any precipitate. An acidified solution of phosphotungstic acid is added to this filtrate so long as a precipitate results, any large excess being avoided. A little powdered glass or sand is then added, the contents of the beaker heated to about 90 C., and filtered, and the precipitate washed with water, also at about 90° C. Assuming that only proteid and amide nitrogen are now present, the former is determined by Kjeldahl’s method in the precipitates and deducted from the total nitrogen previously determined. When peptones are present they are incompletely precipitated by phosphotungstic acid, and the solution should therefore be treated with tannic acid (5 to 10 per cent, solution) and filtered before the addition of the phosphotungstic acid, the nitrogen of the precipitate being estimated and added to the proteid nitrogen. As factors for the conversion of the nitrogen found in the proximate constituents. Mallet prefers the following ; — For proteids and allied substances, multiply the nitrogen by 6-25. For flesh bases and simpler amides of animal origin, multiply by 3'05. For simple amides and amido acids of vegetable origin, multiply by 5 '15. For mixed amido-constituents of unabsorbed solid residues in digestion experiments, multiply by 9 ‘45. The solution of phosphotungstic acid used is a 5 to 10 per cent, solution in 2 '5 per cent, hydrochloric acid. Estimation of the Fat. — After removing all visible fat from flesh, the muscular tissue still contains a considerable proportion, which it is not easy to extract completely. Dormayer * shows that even after extracting dried and powdered flesh for five months with ether, fat is still retained by the tissue. He recommends digesting the flesh with an acid solution of pepsin, and extracting the fat with ether from the solution thus obtained. * Vierteljahrsch. f. Nahr. u. Gemcssm., 1895, p. 325. 84 FLESH FOODS. 0. Franke * steeps 20 grammes of the finely -divided flesh in 100 c.c. of 96 per cent, alcohol for twenty-four hours, with frequent stirring. The alcohol is then drained off, and the treatment repeated twice or thrice with the same quantity of absolute alcohol, and then twice with ether. The residue, freed from ether on the water-bath, is finely powdered and extracted for twenty- four hours, first with ether, and then w'ith petroleum spirit (b. p. 60° C.). E. Volt t gives a simpler method. 100 grammes of the finely- divided flesh are mixed with sufficient alcohol to form a pasty mass, which is dried, with frequent stirring, on the water-bath, in which the water is kept below 80° C. About fifteen hours are required for this. The dried substance is then powdered and passed through a sieve, with a mesh of 0‘4 mm. Four grammes of the flesh thus prepared are dried at 70° C. for twelve hours and extracted with ether for twenty-four hours in a Soxhlet apparatus. The crude fat is dissolved in petroleum spirit, the solution filtered and evaporated, and the residue weighed. The flesh after e.xtraction, tested by Dormayer’s digestion method, still contains from 0‘59 to 1‘7 per cent, of fat, but Voit affirms that the fat obtained by continuing the digestion for longer than twenty-four hours is much less pure, and that the final product of Dormayer’s method is also very impure. A rapid process has recently been described by Liebemann and Szekehj.l Five grammes of the minced flesh are boiled for thirty minutes with 30 c.c. of a 50 per cent, solution of potassium hydroxide (sp. gr. 1-54) in a fliisk of the following description:— The body is 7 -5 cm. in diameter and 5’5 cm. deep, and has a flat bottom. The neck is 19‘5 cm. long and 3 -5 cm. in diameter throughout its length. When filled to about the middle of the neck the flask holds about 290 c.c., and has a mark at 24-0 c c After the boiling the contents of the flask are cooled, mixed with 30 c.c. of 90 to 94 per cent, alcohol, and again heated for about ten minutes. When cold, 100 c.c. of 20 per cent, sulphuric acid (sp. gr. M45) are cautiously added, with constant shaking and continual cooling, in order to avoid a possible loss of volatile fatty acids. The liquid, which finally contains an excess of about 4‘4 grammes of sulphuric acid, is mixed with 50 c.c^^ of petroleum spirit (sp. gr. 0’6 to 0'7 and boiling-point about 60° C.), and the flask closed with a rubber cork, and shaken about thirty^ times at intervals of one or two minutes. A saturated solution of sodium chloride is then added, so that the flask is filled to about * Zeit. f. Biol., 1897, pp. 549-554. t Zeit.f. Biol., 1897, pp. 555-582. ESTIMATION OF FAT — DIGESTIBILITY. 85 the middle of the neck, whilst the aqueous layer below the petro- leum spirit stands at the mark (240 c.c.). i a i • After again being shaken once or twice the closed flask is placed in a vessel of water and allowed to stand at not too high a temperature. As soon as the petroleum layer (which now con- tains the entire fatty acids in solution) has separated, 20 c.c. are pipetted off into a wide-necked flask of about 150 c.c. capacity, mixed with about 40 c.c. of neutral 96 per cent, alcohol, and titrated with decinormal alcoholic potassium hydroxide. The titrated liquid is then transferred to a weighed glass basin, holding about 80 C.C., and provided with a ground glass cover, in which it is cautiously evaporated to dryness on the water-bath at a low temperature, and finally dried for an hour at 100° C., and weighed. In order to calculate the amount of fat, the potassium in the soap must be deducted and the equivalent amount of glycerin radicle added. One c.c. of decinormal potassium hydroxide = 0’00391 gramme of potassium and 0'00136 of (C3H5), so that one must subtract as many times 0-00255 gramme as the number of c.c. of alkali used in the titration. The quantity of fat in the flesh can thus be calculated by the formula : — F= 0-01 -(Ax 0-00255)" a 250 in which F is the percentage of fat required; S the weight of potassium soap from 20 c.c. of the petroleum spirit ; K the number of c.c. of decinormal potassium hydroxide; and a the weight of the substance under examination. According to 0. Polimanti * the following simple method gives practically the same results as the Dormayer digestion process. Two grammes of the powdered flesh are shaken for six hours with 200 c.c. of ether and 2 c.c. of metallic mercury, and the fat deter- mined in an aliquot portion of the filtered extract. THE DIGESTIBILITY OF DIFFERENT KINDS OF FLESH. As the conditions which exist in artificial digestion experiments are very different from those of the natural process it is not wise to base too general conclusions on the results of such experiments. Nevertheless, they may often furnish valuable information as to the behaviour of flesh under the influence of one or more of the * Pfliigor Archiv, 1898, Ixx. 366. 86 FLESH FOODS. many factors which go to form the physiological processes which we term digestion. Artificial Peptic Digestion Experiments. — A simple method of obtaining the gastric juice for such determinations is to cut 'the fresh mucous membrane of a pig’s stomach into small pieces, and to mi.x the fragments with 5 litres of water and 100 c.c. of 10 per cent, hydrochloric acid. After adding a small quantity of an alcoholic solution of thymol as a preservative, the mixture is left for twenty-four hours, with occasional agitation, and is then filtered, first through flannel, and then through paper. Finally the degree of acidity is determined and brought to exactly 0‘2 per cent. As thus obtained the solution of gastric juice can be kept unchanged for months. One of the dried pepsins in the market may be used instead of the freshly prepared gastric juice in the proportion of about 0’5 gramme to 100 c.c. of dilute hydrochloric acid (0'2 per cent.). Five grammes of the lean meat, in as fine a state of division as possible, are mixed in a flask with 500 c.c. of the artificial gastric juice, and the fl;rsk immersed in a water-bath maintained at a constant temperature of 40° C. for three hours. The portion remaining undissolved is then collected on a filter, washed, dried, and weighed, an allowance being made for the amount of water contained in the original flesh. Artificial Pancreatic Digestion Experiments. — For the pre- paration of artificial pancreatic juice a portion of the pancreas of an ox may be well triturated with sand in a mortar, and extracted with cold water, or with a 2 per cent, solution of sodium carbonate. Thymol should be added to the extract as a preservative, as in the case of artificial gastric juice. The digestion experiments are made in the same way as those Avith pepsin, but the liquid instead of being acid should be slightly alkaline (1 per cent, of sodium carbonate). The products formed by the action of pepsin and trypsin on the proteids of flesh are referred to in a subsequent chapter (p. 179). Comparative DvjestibiHtij of Flesh. — Chittenden and Cummins* have determined the relative digestibility of different kinds of flesh by pepsin. In each case 20 grammes of the sample were freed as completely as possible from sinew, fat, skin, and bone, and treated with 5 grammes of pepsin dissolved in a litre of hydrochloric acid (0‘2 per cent.). The amount of cooked beef digested Avas 4'0461 grammes, and this Avas taken as the standard. Kepresenting this amount as 100, the relative digestibility in • Amcr, Chem. Joum., vi. p. 318. ARTIFICIAL AND NATURAL DIGESTION. 87 artificial gastric juice of other kinds of flesh under the same conditions were : — Veal, . 94-89 Mackerel, Mutton, . . 92-15 Herring, . I.amb, . 87-93 Shell-fish, Hen (light flesh). . 86-72 Eel, . ,, (dark flesh). . 84-42 Lobster (female). Salmon, . . 92-29 ,, (male). Trout, . 87-03 Crab, Cod, . 72-39 Frog’s leg. 86-24 82-34 82-5 71-76 79- 06 69-0 67-13 80- 40 The digestibility of raw beef as compared with cooked beef w-as as 142-38 is to 100. Physiological Experiments. — In addition to artificial digestion experiments many physiological experiments have been made on animals and human beings, weighed quantities of flesh or other food being given, and the amount and nature of the excreta determined, the difference being regarded as digested. Thus, in 1862, Ranke showed that in a feeding experiment in which 18-32 grammes of beef were given, 11-5 per cent, of the total nitrogen was found in the waste products. W. Atwater * made experiments on these lines to determine the digestibility of shell-fish in comparison with beef. Of the former about 1550 grammes, and of the latter about 1200 grammes, were eaten by a young man, together with a certain proportion of butter, salt, and spice. The results thus obtained were : — Absorbed. Separated in Excreta. Dry Sub- stance. Nitro- genous Matter. Fat. Salts. Dry Sub- stance. Nitro- genous Matter. Fat. Salts. Fish, . 95-1 98-0 91-0 77-5 4-9 2-0 9-0 22-5 Beef, 95-7 97-5 94-8 78-5 4-3 2-5 5-2 21-5 From these it follows that, in the case of this individual at least, shell-fish is as digestible as beef, and this conclusion received confirmation in similar experiments on a dog. But since the amount of a given food which is capable of being absorbed into the system varies considerably in the case of different * Zcit.f. Biol,, 1887, xxvii. p. 215. 88 FLESH FOODS, individuals, a conclusion as to the absolute degree of digestibility can only be drawn from such experiments when they have been tried with a very large number of people. CALCULATION OF THE FOOD VALUE OF FLESH. This ought to be based not only on the amount of nutriment contained in the flesh, but also on the amount capable of being absorbed and on the efiFect of the flavour. But inasmuch as the two last factors vary with each individual it is only possible to calculate the value approximately from the first, and to regard that food as the cheapest which contains the most nourish- ment. Konig adopts the method proposed by Emmerich, and starts from the fact that the actual market value of nitrogenous sub- stance (proteid) is higher than that of fat, and that carbohydrates are cheaper than fat. If 1 gramme of carbohydrate be taken to represent 1 nutrient unit in value, 1 gramme of fat, and of proteid represent 3 and 5 nutrient units respectively. Thus, for example, if 1 kilo, of beans cost 8d., Proteids, . 230 grammes x 5 = 1150 nutrient units Fat, . . 20 „ X 3 = 60 Carbohydrates, 535 „ x 1 = 535 1745 Here the price of 1 food unit of beans would equal _ „ , ^d. 1745 The following figures taken from Kdnig’s table illustrate this method : — Water. Proteids. Fat. N.-free Extractives. Ash. Sum of nutrient units per kilo. Mutton, very fat, 47-91 14-80 36-39 0 05 0-85 1832-2 Sheep’s tongue, . 67-44 14-29 17-81 0-09 1-00 1230-8 Sheep’s liver. 69-30 21-64 4-98 2-73 1-35 1258-7 89 SYSTEMATIC EXAMINATION OF FRESH MEAT. F. Strohmer* gives the subjoined table of the food value of different kinds of flesh calculated by this method ; Per Cent. Nutrient Units Proteids. Fat. Carbo- hydrates. per kilo. Beef, moderately fat, . „ lean, . Veal, .... Pork, fat, . ,, lean. Lard, Bacon, Game, Rabbit, Heart, Kidney, Liver, Salt Herring, Liver Sausage, . Blutwurst (Blood) Sausage), . J 21-0 21-0 20 14-5 20-0 0-3 5-0 22-5 21-5 18-0 18- 5 20-0 19- 0 11-0 10-0 5-5 1-5 4-0 37-5 7- 0 99-0 78-0 1-0 10-0 8- 0 4-0 40 17-0 14-5 9-0 21-0 20-0 1215 1095 1120 1845 1210 2985 2590 1155 1375 1140 1045 1120 1460 1006 790 According to Lehmann t this empirical method furnishes results which agree fairly well with the actual relation in price. SCHEME FOR THE EXAMINATION OF FRESH MEAT. The following outline for a preliminary examination of raw meat may be serviceable : — 1. The Colour. — Normal. — White, as in lamb or veal ; reddish, as in beef and mutton. _ j. • j i Abnormal. — Melanosis, yellow, white, due to disease ; xantosis, dark purple (acute fever), reddish brown (CO2 poisoning), scarlet (CO poisoning or bacterial deposit). Iridescence, gray, violet, green (incipient decomposition) (c/'. pages 70-72). 2. The Consistency. — A skewer forced into the flesh should meet with equal resistance throughout. The opposite case may denote decom- position or the presence of abscesses. When cut with a knife the division should be even and regular {cf. pages 72 and 77). 3. The Odour. — See pages 73 and 78. 4. The Fat. — This should he present in suitable proportions. Extreme leanness denotes disease {cf. pages 72 and 289). * Die Emahrung des Merischen, p. 324. t Methods of Practical Hygiene, p. 413. 90 FLESH FOODS. 5. Reaction of the Meat Juice towards Litmus.— Acid denotes sound meat or acid decomposition. Alkaline denotes decomposition or presence of alkaline salts as preservatives (c/. page 74). 6. Ebek’s Test for Putrefaction. — This is carried out as described on page 75. 7. Degree of Moisture.— Abnormal moisture, as visible to the eye, is a symptom of several diseased conditions [cf. page 79). 8. Frozen Meat is detected by the appearance of the meat juice to the naked eye and under the miorosoope (page 104). 9. ‘ Blown Meat. — The general (maracteristies are described on page 77. 10. Meat treated with Antiseptics. — (o) Test for decomposition wift litmus and Eber’s test (pp. 74-75) ; (6) Examine the meat fibres under microscope for decomposition and result of action of sulphites (pp. 117 and 121) ; (c) Test the meat juice for borates with turmeric paper (p. 119) ; (ci) Test for salicylic acid (p. 122), and formaldehyde CHAPTER V. METHODS OF EXAMINING ANIMAL FAT. Methods of Examiniiig the Fat.— In the present writer’s opinion the analytical methods described in the following pages \snll be found among the most suitable for the examination of the fat obtained by the methods described in the preceding chapter. For various modifications of these, and for alternative processes, the reader is referred to works dealing specially with fats and oils. Crystallization from Ether.— This may sometimes give an in- dication as to the nature of the fat. Pigs’ fat, excepting that from the flare, is deposited in characteristic crystals with chisel- shaped ends, while beef-fat, mutton-fat, and horse-fat give fan-like bunches of needle-shaped crystals. Hehner and Mitchell * have shown that the form of the crystals depends on the proportion of stearic acid in the fat, and that on continued recrystallization of a lard which at first gives the broad-ended crystals, the deposits be- come more and more rich in stearic acid, and eventually assume the form of the crystals from beef-fat. Specific Gravity. — Accurate results are most readily obtained by the use of a Sprengel U-tube. Melting Point. — The method adopted by the Association of Bavarian Chemists consists in drawing the melted fat into a thin capillary tube, sealing one end, and leaving it for twenty-four hours. The tube is then tied to the stem of a thermometer, which is gently heated in a glycerin bath. The temperature at which the fat becomes perfectly clear and transparent is regarded as the melting point. Solidifying Point of the Fatty Acids. — The fatty acids are melted in a test-tube and allowed to cool slowly until signs of incipient solidification appear, when they are stirred with a ther- mometer, graduated in fifths of a degree three times to the right and three times to the left. At a certain stage after this the mercury in the thermometer ceases to fall, and then suddenly * Analyst, 1896, p. 329. 92 FLESH FOODS. rises, often as much as half a degree, and remains stationary for a short time before commencing to fall again. This stationary })oint is taken as the solidifying point, and is also known as the Dalican ‘ titre.’ By using the same apparatus and details of pro- cedure concordant results are readily obtained by this method. The Iodine Value. — This indicates the percentage of iodine or oth'er halogen, calculated into its equivalent of iodine, absorbed by a fat. Hiihl Process. — The method which has hitherto been most widely employed is that of Hiibl, varied in the details of working by various chemists. The following is an outline of a method of procedure which, in essential particulars, is the same as that of Hiibl Two solutions are prepared: (1) containing 25 grammes of iodine in 500 c.c. of pure 95 per cent, alcohol (or rectified spirit), (2) containing 30 grammes of mercuric chloride in 500 c.c. of the same solvent. About 0’3 gramme of liquid fat, or O'S gramme of solid fat are dissolved in 10 c.c. of chloroform in a stoppered bottle. To the solution are added (1) 20 c.c. of the iodine solution, and (2) 20 c.c. of the mercuric chloride solution. Simultaneously a blank -deter- mination is made, the same quantity of chloroform and of the solution being placed in a stoppered bottle containing no fat. After three hours 10 c.c. of a 10 per cent, solution of potassium iodide is added to each bottle, and the liquid in each titrated with recently standardized sodium thiosulphate, starch paste being used as indicator. Tlie difference between the blank determination and the other gives the amount of iodine absorbed by the quantity of fat taken. Care must be taken that there is always an excess of iodine during the absorption. From Wijs’ experiments * it appears that the results are more accurate if the blank be titrated before the absorption rather than after it, and also that seven hours is a somewhat better time limit than three hours. BTys’ Method. — Recently Wijs’ t has thrown light on the nature of the reactions which bike place on mixing the Hiibl solutions and adding them to a fat, and has shown that the substance chiefly concerned in the absorption of the iodine is hypoiodous acid (HIO), formed by the action of the water present on the iodine chloride derived from the double decomposition between the iodine and the mercuric chloride. As this acid is extremely unstable, he has devised a means of obtaining it under such conditions as largely prevent its decom- * Analyst, abst., 1809, p. 95. t angew. Chem., 1898, p. 291. determination Of THE IODINE VALUE. 93 nosition This is effected by preparing it by the action of water oriodine chloride (ICl + H^O = HCl + HIO), a solvent being chosen which contains only so much water as will decompose nearly the whole of the iodine chloride, and which at the same time be oxidized by the hypoiodous acid. A solution of iodine chloride in 95 per cent, acetic acid fulfils these conditions. This is prepared by dissolving 13 grammes of iodine a litre of acetic Lid, titrating the solution with standard thiosulphate and passing a current of chlorine through, until the quantity of tWosSphate required is doubled. With a little praot.ee this point can be readily found by the change in colour. ^ _ The solution thus obtained is fairly stable, and is "sed m the same way as the mixed Hiibl solutions, with the exception that the length of time required for the absorption is very greatly reduced, the addition being complete in three or four minutes in the case of fats and oils with low iodine values, while not more than ten minutes are necessary with oils with high iodine values. _ The Bromine-Thermal Method. — This method, devised by Hehner and Mitchell,* affords a rapid means of determining the iodine value. It depends on the facts that on adding bronnne to a fat or oil a considerable amount of heat is liberated, and tha this heat is proportional to the degree of unsaturation. One gramme of the fat or oil is dissolved in 10 c.c. of chloroform or carbon tetrachloride in a test-tube packed with non-conducOng material in a beaker, or preferably in a vacuum-jacketed tube, j A delicate thermometer (graduated in fifths or tenths of a, degree) is inserted, and the temperature observed. One c.c. of broinme, previously brought to the same temperature as the chloroforni solution, is then introduced, and a note made of the highest temperature reached. The difference between the initial and the final temperatures is the ‘ bromine-heat value. By accurately determining the bromine-heat value and the iodine value of a number of edible fats and oils a ratio can be worked out between the two, so that subsequently it is only necessary to determine the bromine-heat value and to multiply it by the factor, in order to obtain the iodine value. Of course the same apparatus and method of working must alone be used or the factor will be a different one. The Saponification or Kbttstorfer Value. — This indicates the amount of potassium hydroxide, in milligrammes, required to exactly convert the fatty acids in 1 gramme of a fat into the potassium salts, with complete liberation of the glycerin. Hot Saponification. — From 1'5 to 2 grammes of the fat are * Analyst, 1895, p. 146. t These may be obtained from F. M tiller, Holborn. 94 FLESH FOODS. mixed in a flask with an accurately measured excess of standard alcoholic potassium hydroxide, and heated on a boiling water-bath under a reflux condenser for about thirty minutes. The liquid is then titrated back with semi-normal acid, with phenol-phthalein as indicator. The alcoholic alkali is prepared by dissolving about 30 grammes of potassium hydroxide in a little boiling water, making up the solution to a litre with purified alcohol, and filtering it after standing for twenty-four hours. Cold Saponification.* — From 3 to 4 grammes of the fat are dissolved in 25 c.c. of petroleum spirit and the solution mixed with 25 c.c. of standardized alcoholic potassium hydroxide (con- taining as little water as possible). The saponification is usually complete in a few hours, but it is advisable to allow the flask to stand overnight before titrating back the excess of alkali. Hehner Value. — This shows the percentage of insoluble fatty acids contained in a fat or oil. From 3 to 4 grammes of the fat are weighed into a small evaporating dish, where they are mixed with 1 to 2 grammes of potassium hydroxide and 60 c.c. of alcohol, and heated on the water-bath until completely saponified. The soap is evaporated to a pasty consistency and dissolved in about 1 50 c.c. of boiling water, the fatty acids liberated by adding hydrochloric or sulplniric acid, and the flask heated on the water-bath until they melt and form a clear layer on the surface. The contents of the flask are then poured on to a filter of thick paper, previously dried at 100° C., and weighed, and the insoluble fatty acids left on the filter are washed with boiling w'ater until the filtrate ceases to redden litmus. The filter-funnel is then immersed in cold water, which generally causes the fatty acids to solidify. The water is drained off, and the filter and its contents dried at 100° C. in a beaker of known weight. The weighings, taken after two hours’, and again after 4 hours’ drying, usually agree within a milligramme. The Reichert Value. — This indicates the definite proportion of volatile fatty acids obtained from 2 ‘5 grammes of a fat by Reichert’s distillation process. Two and a-half grammes of the purified and filtered fat are weighed into a small flask, fitted with a cork through which passes a short piece of glass-tubing, and saponified by adding 5 c.c. of pure alcohol and 6 c.c. of a concentrated aqueous solution of potas- sium hydroxide (free from carbonate) and heating on the water- bath for a short time. After expelling all traces of alcohol the dry soap is dissolved in 70 c.c. of boiling water, and the fatty acids * R. Henriques. Zeit. angew. Chem., 1895, p. 721 ; 1896, p. 221. Analyst, 1896, pp. 67 and 192. 95 THE REICHERT, ACETYL, AND ACID VALUES. liberated by adding 5 c.c. of stdphuric acid of the right strength to neutralize the alkali. A few pieces of pumice are introduced into the flask to prevent bumping, and the liquid gently distilled until exactly 50 c.c. of liquid have passed over. This distillate is filtered, the filter washed with boiling water, and the filtrate and washings titrated with decinormal solution of potassium or barium hydroxfde. The number of c.c. required is the Reichert value. In the Reichert-Meissl process 5 grammes of the fat are used, and the number obtained is considerably higher than the Reichert value. The Acetyl Value. — This indicates, among other things, the amount of hydroxylated fatty acids present in a fat. The method which gives the most reliable results is that of Lewkowitsch,* who defines the value as the number of milli- grammes of potassium hydroxide required to neutralize the acetic acid obtained by saponifying 1 gramme of the acetylated fat. The glycerides of any hydroxylated acids present are converted into their acetyl compounds by boiling the filtered and purified fat for two hours with an equal volume of acetic anhydride. The oily product is boiled with successive portions of water until the latter has no longer an acid reaction, and is then freed from water and filtered. From 2 to 4 grammes of the acetylated fat are saponified with a definite volume of standard alcoholic potassium hydroxide, the alcohol evaporated and the soap dissolved in boiling water. The amount of acetate present is then determined by either a distilla- tion or a filtration process. In the former an excess of sulphuric acid is added, from 500 to TOOc.c. of the liquid distilled by blowing a current of steam through the flask, and the distillate titrated with standard alkali. In the filtration process, a quantity of sulphuric acid exactly equivalent to the alcoholic potassium hydroxide used is added, the liquid warmed, the layer of fatty acids filtered off and washed with boiling water, and the filtrate and washings titrated with standard alkali. Free alcohols will also be saponified, and, if present in any quan- tity, a correction must be made for them. A correction is also necessary when the fat contains any considerable proportion of volatile fatty acids (high Reichert value), t The Acid Value. — This indicates the amount of free fatty acids present in a fat. A weighed quantity of the fat is mixed with neutral alcohol, heated on the water-bath until the alcohol boils, and titrated with * Jowr. Soc. Ghem. ItuI., 1897, xvi. pp. 503-606. t The meaning of the acetyl value in fat-analysis is exhaustively discussed in a recent paper by Lewkowitsch {^Analyst, 1899, p. 399). 96 FLESH FOODS. a standard solution of potassium hydroxide. The number of milligrammes of potassium hydroxide required to neutralize the free fatty acids in 1 gramme of fat gives the acid value. DETERMINATIOl^ OF INDIVIDUAL CONSTITUENTS. Separation of Liquid and Solid Fatty Acids. — Treatment of the Lead Soaps toith Ether. — Several methods * have been based on the fact that the lead salts of the unsaturated fatty acids are much more soluble in ether than those of the solid fatty acids (Varren- trapp). In each case there is only a fractional separation or con- centration, and the portion soluble in ether, although very much richer in liquid fatty acids, still contains solid fatty acids, while the insoluble portion is not free from liquid fatty acids. As, how- ever, it is possible, by working under exactly the same conditions, to obtain concordant results, the method in one or other of its modifications is widely employed, and often aflfords valuable information. The following process is essentially that of Rose : — One gramme of the mixed fatty acids is placed in a stoppered flask with 0 5 gramme of lead oxide, and about 80 c.c. of ether, and after standing for twenty-four hours, with an occasional shake, the liquid is made up to 100 c.c. with ether, the flask well shaken, and the insoluble matter allowed to settle. Twenty-five c.c. of the ether are then withdrawn by means of a pipette, the end of which is covered with a porous plug of cotton-wool, to serve as a filter. The solvent is evaporated and the residue dried in a current of carbon dioxide, and weighed. The lead it contiiins is then determined by adding 2 5 c.c. of dilute sulphuric acid (I : 5), digesting on the water-bath, adding 40 c.c. of 95 per cent, alcohol, collecting the lead sulphate on counterpoised filters, washing it with alcohol, drying and weighing. From the percentage of lead in the dried sulphate the proportion of fatty acids which were in combination with it in the residue may be calculated, and also their molecular weight. Determination of the Iodine Value of the ‘ Liquid ’ Fatty Acids. — Fifty c.c. of the ethereal solution are withdrawn from the flask with the filter pipette and shaken with dilute hydrochloric acid in a separating funnel, in order to liberate the fatty acids ; the ethereal layer is washed with successive portions of water until free from chloride, after which 25 c.c. are withdrawn and evapor- ated to dryness in a weighed flask, and the iodine value of the residue determined in the usual manner. From the time of the liberation of the fatty acids the greatest care is necessary, to t Oudemans, J. prak. Chem., 99, p. 407 ; Muter and De Koningh, Analyst, 1889, p. 61 ; Kremel, Fharm. Centralh., 5, p. 337 ; Rose, J. Hoc. Chem. Ind., 1887, p. 306. METHODS OF SEPARATING FATTY ACIDS. 97 prevent their oxidation, and throughout the washing and evapora- tion the air in the separating funnel and the llask must be replaced by carbon dioxide. (ii.) Treatment of the Lead Soap with Benzene. — Finding that the lead salts of the unsaturated fatty acids were much less soluble in benzene than in ether, Farnsteiner * has devised the following method of separation, in which his experiments with known mix- tures show that the proportion of liquid fatty acids obtained are from 1 to 3 per cent, too low, while that of the solid acids is in the maximum 1‘65 per cent, too high : — I’rom 0'6 to 1 gramme of the fat is saponified in an Frlenmeyer flask with alcoholic potassium hydroxide, the solution neutralized with acetic acid, and, after evaporation of the alcohol, the soap dissolved in 100 c.c. of boiling water and precipitated with 30 c.c. of a boiling solution of lead acetate (containing about 1 gramme). When cold the liquid is filtered and the residue in the flask washed with cold water, freed from the latter as completely as possible, and dissolved in 50 c.c. of hot benzene. The solu- tion is left at the ordinary temperature for fifteen minutes, and is then cooled for about two hours at 8° to 12° C. In order to separate the liquid from the crystalline deposit, the flask is closed with a cork, having two holes, through one of which passes a short straight tube, while the other holds a tube reaching to the bottom of the flask and having its exterior end bent downwards outside the flask. The interior opening of the tube is covered with a plug of cotton wool which serves as a filter, and the liquid is driven upwards through this by forcing air into the flask through the short straight tube. When the liquid has been removed as completely as possible in this way, the flask is washed with 10 c.c. of benzene at 10° C., which is similarly expelled. The precipitate is then dissolved in 25 c.c. of hot benzene, again cooled for an hour at 8° to 10° C., and the liquid again filtered. In the same way a third precipitation and filtration are carried out, so that alto- gether from 120 to 130 c.c. of the benzene filtrate are obtained. The liquid fatty acids are recovered from the united filtrates by shaking the latter with 10 c.c. of hydrochloric acid, filtering the solution of fatty acids through cotton wool, into a flask, and distil- ling oif the benzene in a current of hydrogen, to prevent oxidation. The solid fatty acids are determined by heating the insoluble lead salts in a flask with 25 to 30 c.c. of benzene for a short time, then adding dilute hydrochloric acid (1:10), continuing the heating for about fifteen minutes under a reflux condenser, washing the solu- tion, and evaporating the benzene. When free fatty acids are to be examined the best method is to * Zeit. Nahr, u. Genussm.f 1898, 1, pp. 390-399. G 93 FLESH FOODS. dissolve them in benzene and to heat the solution under a reflux condenser with lead hydroxide, obtained by precipitating a solution of lead acetate with sodium hydroxide, washing the precipitate with water, alcohol, and ether, drying it at a gentle heat, and finely pow- dering it. The proportions required for one part by weight of solid and liquid fatty acids are 0’4 and 0’2 parts respectively. Determination of the Iodine Value of the Liquid Fatty Adds. — This may be done with the residue of acids obtained in the manner described above, every precaution having been taken to prevent their becoming oxidized. The risk of oxidation is greatly reduced and the manipulation simplified by determining the iodine value of the fatty acids while still in solution in the benzene. Farnsteiner has found that benzene from which all thiophene has been removed does not absorb a trace of iodine on treatment with Hiibl’s solution, and on this fact bases the following method : — From 1 to 2 grammes of the fat are converted into the lead salts of the fatty acids in the usual manner, and dissolved in 100 c.c. of benzene (free from thiophene) at a gentle heat. After being left for ten to fifteen minutes, until a precipitate commences to form, the flask is allowed to stand for two hours at a tempera- ture of from 8° to 12° C., and the liquid then filtered without subsequent washing of the precipitate. After shaking the filtrate with about 100 c.c. of dilute hydrochloric acid (1:10), until the fatty acids are liberated, the benzene solution is washed twice with water and filtered. Two portions of 25 c.c. are taken from the filtrate and treated with the Hubl solution in the usual manner, wliilst a similar third portion is evaporated in a current of hydrogen, and the residue weighed in order to determine the quantity present in the other fi*actions. Benzene t can be freed from thiophene by heating 120 c.c. to the boiling point under a reflux condenser with 5 ’8 grammes of aluminium chloride, and distilling, care being taken to exclude moisture. The distillate is washed with sodium hydroxide solution and dried with calcium chloride. Treatment of the Zinc Salts with Ether. — In Jean’s method the fat is saponified with alcoholic potassium hydroxide, the excess of alkali neutralized with acetic acid, and the alcohol evaporated on the water-bath. The soap is dissolved in hot water, a hot solu- tion of zinc acetate (1 part to 2 parts of fat) added, and the zinc soap washed with hot water and alcohol, pressed between filter- paper, and extracted with about ten times its volume of anhydrous ether for fifteen to thirty minutes, under a reflux condenser. After cooling, the solution is filtered into a separating funnel, * Zeit. UnUrsuch. Nahr. Genuusm., 1898, p. 529. + Heusler, Zeit. mgew. Chem., 1896, p. 750. ESTIMATION OF STEARIC ACID, 99 shaken with dilute hydrochloric acid, and the ethereal layer con- taining the liberated fatty acids, washed with water, and parts of it filtered into weighed flasks, w'here the ether is evaporated and the iodine value of the residues determined in the usual way. During the filtrations and evaporations every precaution is taken to prevent oxidation. Bomer * has recently made experiments on the determination of the iodine value of the zinc salts without previous conversion into fatty acids. He points out that since the molecular equivalents of the higher unsaturated fatty acids differ but slightly, a variation in the percentage of those acids in a mixture would not have a very great influence on the result. Thus 100 parts of oleic acid correspond to 111-19 of zinc oleate; 100 of linolic acid to 111-27 of zinc linoleate; and 100 of linolenic acid to 111-35 of zinc linolenate. Hence, without risk of a considerable error, the mole- cular equivalent of the zinc salts of mixed liquid fatty acids may be taken as that of the oleic acid salt (627-1) ; and since 100 parts of zinc oleate correspond to 89-94 parts of oleic acid, the iodine value of the liquid fatty acids (taken as oleic acid) may be calcu- lated by dividing that of the zinc soap by 0-8994 or multiplying it by 1-112. (iii.) Treatment of the Fatty Acids with Sulphuric Acid and Extraction of the Saturated Acids with Petroleum Spirit.-\ — From 0-5 to 1 gramme of the fatty acids are melted in an Erlenmeyor flask, the flask chilled in ice water, 3 c.c. of 85 per cent, sulphuric acid added, and the temperature allowed to rise. When once the reaction commences a clear solution is rapidly obtained, and the flask is again cooled. Fifty c.c. of petroleum spirit are then introduced, the flask well shaken, the petroleum spirit decanted into a separating funnel, the flask rinsed out twice with 10 c.c. of petroleum spirit, the total extract washed with water, the solvent evaporated, and the residue, consisting of the saturated fatty acids, dried and weighed. J Determination of Stearic Acid. — Hehner and Mitchell § have devised a method of estimating this constituent, in which the fatty acids are crystallised from alcohol previously saturated with pure, or nearly pure, stearic acid, at a definite temperature. The stearic acid is most readily obtained by recrystallising the fatty- acids of cocoa butter from alcohol until a product is obtained which melts between 68° and 69° C. An excess of this is dissolved m 95 per cent, alcohol, and the flask kept immersed for twelve ■* Zeit.f. Untersuch. Nahr. Qenussm., 1898, p. 541, t E. Twitohell, Journ. Soc. Chem. Ind., 1897, p. 1002 § Analyst, 1896, p. 316. 100 FLESH FOODS. liours in ice-water. In the morning the liquid is drawn off by means of a suction filter, without withdrawing the flask from the ice-chest. The filter consists of a thistle funnel covered with a linen cloth, and the method of manipulation is shown in the is JmeltabU. It might b« posible, however to obtain setutactoiy teaults by prSusly saturatini the solvent with pure barium oleate. ESTIMATION OF LINOLIC AND LINOLENIC ACIDS. lUl The barium salts of the fatty acids can also be prepared directly from the fats by saponifying them with a solution of barium hydroxide in equal volumes of benzene and methyl alcohol. ‘^Determination of Linolic Acid. — According to Farnsteiner it is possible to estimate this acid by taking advantage of the insolubility of its bromide in cold petroleum spirit. The fatty acids of the oil or fat are dissolved in chloroform or petroleum spirit, the solvent and excess of bromine evaporated, and the deposit filtered off, washed, dissolved in petroleum spirit, recrystallised, collected, and weighed. As a rule it was necessary, where only small quantities of linolic acid were present, to brominate the liquid fatty acids (p. 97), or the soluble fatty acids obtained in the separation of oleic acid as a barium salt (p. 100). In this way lard was found to contain traces of both linolic acid and linolenic acid. Horse fat contained 9 ’9 per cent, of linolic acid, which was also found in ox-tallow, accompanied by traces of linolenic acid. Determination of Linolenic Acid. — Indirect Estimation. — Hehner and Mitchell* have devised the following method:— On adding bromine to a chilled acetic acid solution of the total liquid fatty acids of an oil, there is an immediate precipitate if linolenic acid be present in more than traces, but this may also contain linolic bromide if it be present in any quantity. The preeipitate is collected on a filter, washed, first with cold acetic acid so as to remove oleic dibromide, and then with very cold ether, dried, and weighed. The bromine it contains is deter- mined, and the relative proportion of linolenic hexabromide calculated by means of the formula 63-3a; , (100 - a;)53'3 100 100 or a:= 10(m - 53'3), in which m equal the percentage of bromine found, x the reqtiired percentage of hexabromide, and 63‘3 and 53'3 the respective percentages of bromine in the pure hexa- and tetra-bromides. Direct Estimation. — In Farnsteiner’s method of estimating linolic acid {vide supra) it was found that in some cases the bromides of the liquid fatty acids were not completely soluble in hot petroleum spirit, and that the insoluble residue had the characteristics of linolenic hexabromide. Hence it seems probable that this may be made the basis of a method of separating linolic and linolenic acids. * Analyst, 1898, p. 314. CHAPTER VI. THE PRESERVATION OF FLESH, AND THE COMPOSI- TION AND EXAMINATION OF PRESERVED FLESH PRODUCTS. The Decomposition of Flesh. The organic substances wliich compose the cells of the animal tissues and fluids are, as it were, in a state of unstable eq\iilibrium, a constant series of molecular changes going on, with destruction and reconstruction of the cell materials. So long as the cell is endowed with the force known as ‘ life,’ it is able to resist the dis- integrating effect of the numerous micro-organisms which, under suitable conditions, speedily break down complex animal com- pounds into simpler and more stable bodies. But when once the cell is dead, the process of decay or putrefaction speedily com- mences, unless means be taken to destroy or render inert the bacteria already present, and to prevent the access of others. Tlie conditions essential for the bacterial decomposition of flesh arc the presence of a sufficient quantity of moisture, and a suit- able temperature, while the presence of atmospheric oxygen is often an accelerating influence. The methods adopted in the preservation of meat are based on a considenition^ of these facts, and for convenience may be con- sidered under the following heads : — 1. Preservation by Cold ; 2. Drying ; 3. Salting; 4. Smoking; 5. Heat-Sterilisation and Exclu- sion of Air; 6. Antiseptic Agents. Obviously this classification is by no means an exact one, as the divisions overlap one another in many cases. Preservation by Cold. This method of preservation is perhaps more extensively employed than any other, especially in Russia, where the climate is favour- able for its natural application. Preservation by means of arti- PRESERVATION OF FLESH FOODS : COLD. 103 ficial cold is also in general use, and enormous quantities of frozen meat are daily supplied to the markets of London and other large citios* Tiie numerous methods of cold preservation which have been described are based upon either (1) freezing the flesh and keeping it frozen ; or (2) keeping it at a temperature of only a few degrees below zero (C.). Alterations in Frozen Flesh. — Owing to the slow, continuous action of the sarcolactic acid, meat which has been frozen is often exceptionally tender. On the other hand, owing to the loosening of the intermuscular tissue, bacteria can more readily penetrate into the interior of the thawed flesh, and bring about more ra,pid decomposition. Considerable care is required in the thawing, since if this be done too suddenly the meat when cooked is often wanting in flavour. Action of Cold on Bacteria. — Bacteria in general, and especi- ally those which bring about putrefaction, appear to be endowed with extraordinary powers of resistance to the action of cold. Pictet and Young* exposed cultivations of anthrax bacilli, of B. mhtilis, and of other bacteria, in wooden boxes, to a tempera- ture of - 70° to - 76° C. for twenty hours, and finally for a long period at - 76° to - 130° C., but did not succeed in destroying their vitality. Colemann and Mickendrick* obtained similar results. In their experiments flesh was kept for at least six hours in hermetically-sealed boxes at temperatures from -6° to -130° C. , but in every instance the flesh, after being kept at a slightly warm temperature, began to decompose in from ten to twelve hours, though protected from subsequent infection. But cold, although it does not destroy micro-organisms, pre- vents their development, or at least does so in the case of the putrefactive bacteria, which at low temperatures are unable to decompose the proteids of flesh. There are, however, certain non- proteolytic bacteria which are capable of developing in frozen meat, and especially in that which is kept at a temperature of 0° C., instead of several degrees lower. To this cause Lafar t attributes the unpleasant flavour sometimes acquired by meat which has been kept in an ice-chamber for several days. This is confirmed by Popp,J who states that in cement- lined storage chambers the walls, when moist, swarm with bacteria, which, when grown on beef-gelatin, produce a mouldy flavour, and he considers them to be the cause of the objectionable flavour frequently developed in stored meat. * Ostertag, Hayidhuch der Fleischbeschau, p. 535. t Technical Mycology, p. 213. t Zeit, Fleisch u. Milch Hyg., 1898, p 33. 104 FLESH FOODS. The Detection of Frozen Meat.— men fresh blood is exposed to a temperature of from 10° to 1.5° below zero (C.), it solidifies, and, when examined under the microscope, shows ruptured cor- puscles. This was first described by G. Pouchet in 1866, and has been applied by Maljean* to the recognition of frozen meat. A drop of the blood or meat-juice is expressed from the meat on to a glass slide, covered with a thin glass, and placed under the micro- scope as rapidly as possible in order to avoid solidification. The juice from fresh meat shows numerous red corpuscles of normal colour and shape floating in a colourless serum, whereas the cor- puscles in the drop taken from the frozen meat are all more or less distorted in form, and completely decolorised, whilst the sur- rounding liquid has a relatively dark colour. A diflerence is also apparent to the naked eye, the juice from fresh meat being more abundant and of a redder tint than that from frozen meat. On placing a fragment of the frozen meat in a test-tube containing some water, the liquid becomes coloured much more rapidly and intensely than when fresh meat is used. Preservation by Drying. During the process of drying in the sun or by artificial heat flesh loses a large pi'oportion of its water, so that in the finished product one of the essential conditions for the development of bacteria is absent. As a rule such preparations keep well if pro- tected from moisture, but during the drying they lose much of the flavour of the fresh meat. The best-known examples of this method of preservation are the American preparations, jjemmican, and charque, and flesh powder. Pemmican. — This was formerly prepared by the North Ameri- can Indians from buffalo flesh, but now usually consists of beef. The flesh is cut into strips, dried in the sun, minced as finely as possible, mixed with equal quantities of fat, and worked up into a paste. According to Dr. Chaumont the finished product contains about 35 per cent, of nitrogenous substance and 56 per cent, of fat. Charque. — Enormous quantities of this form of dried flesh are prepared in various parts of South America. The meat, after removal of the fat as completely as possible, is cut into thin strips, which are covered with flour, dried in the sun, and rolled and pressed into a compact mass. In Brazil it is mixed with sugar before drying {charque dulce), or salted and dried {came secca), or salted and pressed between stones before drying (came Tassajo). * Journ. Pharm. Chim., 1892, 25, p. 348. PRESERVATION OF FLESH FOODS: DRYING, 105 According to Chevalier* it should have a dark red colour, the muscular fibre should be hard, and no liquid should exude on applying strong pressure with the fingers. Beef loses about a quarter of its weight in the process. _ Hofmann t gives the following figures as representative of the composition of fat and lean charque : — Per Ceut. Dry Substance. Water. Nitro- genous Sub- stances. Fat. Salts. Sodium Chloride. Nitro- genous Sub- stances. Fat. Nitrogen. Fat Charque, . 40-2 48-4 21 8-3 6-3 80-93 5-17 12-95 Lean Charque, 361 46-0 3-7 15-2 141 71-98 4-22 11-91 In 1855 Giradin \ made the following comparative analyses of the composition of French beef and South American charque : — French Beef. Charque. Fresh. Dried at 100° C. As Imported. Dried at 100° C. Water, . 75-9 49-11 Fibrin, . 15-70 6.5-4 24-82 48-78 Fat, 1-01 4-19 018 0-35 Albumin, 2-25 9-34 0-70 1-38 Extractives, , 2-06 8-55 3-28 6-44 Soluble Salts, 2-95 12-24 21-07 41-39 Phosphoric Acid, . 0-222 0-925 0-618 1-216 Nitrogen, 3-000 12-578 4-620 9101 Sodium Chloride, . 0-489 2-030 11-516 22-630 But although charque is richer in phosphates and nitrogenous substances than fresh beef, it can only be eaten in small quantities on account of the large amount of salt which it contains, and this also renders it extremely hygroscopic. Moreover, any fat which * Diction, des Alterations et Falsifications, p. 561. + Bedeutung der Fleischnahrung, p. 162. + Diction, des Alterations et Falsifications, p. 562. 106 FLESH FOODS. is left in it is very liable to become rancid. Hence, in spite of its cheapness (25 to 35 centimes per kilo, in La Plata), it has never come into general use in Europe. Flesh Powder. — Various preparations of powdered flesh or flesh powder have been introduced into commerce, but, as a rule, the difficulty has been to prevent them acquiring an unpleasant flavour from alterations in the fat which they contain. Konig has confirmed Rubner’s statement, that such dried flesh is as digestible as fresh meat. The lean flesh is dried first on the surface in a special apparatus at a low temperature, which is subsequently raised. When dry the flesh is pulverised and salted. The following analyses of a German patent flesh powder (‘ came 2mra’), which is no longer in the market, have been made by Konig * and Strohmerf : — Water. Nitro- genous Sub- stances. Fat. N.-free Extrac- tives. Salts. Potas- sium. Phosphoric Acid. Kunig, 10-99 69-50 6-84 0-42 13-26 1-85 1-62 Strohmer, . 10-81 70-24 5-61 ... 13-34 ... ... Strohmer also found that 97 '56 per cent, of the nitrogenous substance was of a proteid nature, and that 99‘2 per cent, of this was digestible. The ash contained 8-77 per cent, of sodium chloride. Various substances, such as biscuits, meat cocoa, chocolate, etc., have been prepared from such flesh powder. Strohmer gives the following results of the analyses of some of these preparations con- taining ‘ came pura ’ : — Water. Nitrogenous Substance. Fat. Carbo- hydrates. Ash. Digestible Nitrogenous Substances. Meat biscuit, 6-98 12-56 12-37 67-09 2-00 92-5 „ cocoa. 6-25 22-63 30-13 34-66 6-34 65-7 ,, chocolate, . i 2-10 10-76 25-83 69-10 2-22 72-7 * Loc. cit., ii. t Die Emahrutig des Menschen, p. 130. PRESERVATION OF FLESH FOODS : SALTING. 107 The writer is indebted to Mr. Otto Hehner for the following analyses of English meat biscuits which are still manufactured : . ^ , A Starch, etc., Water. Pat, Albumin. Cellulose. Ash. (jjff 0i*0U(;0, English meat biscuit, 7’53 16’77 16'05 0'97 1‘68 57 00 Dried Fish. — In many places small cod, haddock, and stockfish are preserved by slitting them down the middle and drying them in the air. Dried stockfish (Kabeljau) is very extensively used. According to Strohmer * it contains : — Water, 16T6 ; nitrogenous matter, 78‘91 ; fat, 0'78; and salts, 1'52. It is as digestible as flesh powder, and costs less. Blood Meal. — In Sweden purified, dried blood, in the form of a powder, is a common article of food.* Preservation by Salting. This is one of the oldest and most widely used processes of preserving meat. The salt acts partially as a dehydrating agent, combining with the water in the flesh, and partly as an antiseptic, though its value in the latter respect has frequently been over- rated. Methods of Salting. — In one method the flesh is well rubbed with salt, then pressed, the salting repeated, the meat being finally placed in barrels and covered with the salt liquid obtained from the pressings. Another method consists in placing the meat in casks in layers, with salt between each layer. The salt withdraws water from the flesh, and the brine formed penetrates the fibres. In Eckart’s Munich quick-salting process, the meat is impreg- nated, under pressure, with a 25 per cent, solution of sodium chloride for twenty-four hours, and then smoked. It is claimed that the loss consists, in the main, of only water and a little phos- phoric acid, that the meat has a better flavour, and that any trichinae are completely destroyed. Cirio’s process, first exhibited in Paris in 1867, is very similar in character, the meat being kept in vacuo and brine forced in. Addition of Nitre. — As one of the results of salting meat is, that decolorisation takes place, it is customary to add a small proportion of potassium nitrate to counteract this. According to Lehmann a very little suffices, but it must not be lost sight of that nitre is a poisonous substance. Five grammes of the salt may cause severe illness, and 8 grammes have been known to * Loc. cit., p. 132. 108 FLESH FOODS. cause death. The effect on the human system of the continued use of meat containing nitre has not yet been determined. Influence of Salting on Bacteria. — From the experiments of Forster * it appears that the streptococci of erysipelas, the bacilli of swine erysipelas, and Streptococci pyogenes can live for weeks, and even months, in salted flesh. The bacilli of tuberculosis retain their virulence for over two months, and while the bacteria of anthrax perish in from eighteen to twenty-four hours, their spores retain their vitality for a very long period. Influence of Salting on the Flesh. — Voit’s analysis* tends to show that the nutritive value of flesh is only slightly diminished after fourteen days’ salting. He found the percentage loss to be — Water, 10'4; organic matter, 2T ; albumin, IT; extrac- tives, 13 '5; phosphoric acid, 8 '5. The amount of salt taken up by 1000 grammes of the fresh flesh was 43’0 grammes. E. Polenske,t however, found that beef, after being pickled for three weeks, had lost I'll per cent, of its nitrogenous con- stituents, and 34-72 per cent, of its phosphoric acid. After three months the loss in nitrogen was 10 08 per cent., and the loss of phosphoric acid (P2^5) 54'46 percent., while after six months these figures had risen to 13'78 and 54-60 per cent, respectively. From this Polenske concluded that the meat was completely altered in character as a nutrient substance. Moreover, on account of the large amount of salt, it cannot be used as a substitute for fresh meat for a continued period without injurious effects. Strohmer J gives the following comparative analyses of the com- position of fresh and salted herring, and of salted anchovies : Water. Nitrogenous Substances. Fat. Ash. Sodium Chloride. Fresh Herring, 80-71 10-11 7-11 2-07 • •• Salt Herring, 46-2 18-9 16-9 16-4 14 0 Salt Anchovies, 57-8 22-3 2-2 23-7 20-0 The Composition of the Pickling Fluid. — In Polenske' s experi- ments this liquid contained nitre and salt, and as the pickling proceeded, the nitrate became reduced to nitrite and ammonia. Gerlach § gives the following analysis of an old herring pickling * Ostertag, loe. dt., p. 526. J Loc. cit., p. 133, t Jahresber. Nahr. u. Ocnussm., 1891, p. 40. § Handbuch der Fleischkundc, p. 898. PRESERVATION OF FLESH FOODS: SALTING. 109 fliilfl • Water 74’40: sodium chloride, 22-78 ; ammonium lac- ■'oL soluble proteid snbstanees. 0'820 ; other orgumo Her ,,o4ssiri sulphate, and calcium phosphate. 1-352 per cTurH^ffmann* * * § andVerthe also found ™latile_^~^^ St^'r^ror^aLTirotorery poLnous to Ca^ar —This is the salted roe of the sturgeon and of other fish. It ?s™red by washing the roe with saltwater, leaving it m brine for some time, pressing it to ^ aaain treatin^^ it with salt water, pressing it through a hair sieve, SrAnally^lcking it in salt. In the fresh state caviar is of a greenish shade, which gradually darkens on ^ ^ The most prized is the Astrachan caviar, which is prepared at the mouth ?f the Volga. The German Elbe caviar contains smaller granules, and is prepared from different ^ ® has a sharper taste than the Russian caviar. There is also an American vLiety, which has small granules, and contains more or ^^^oS^of the best kinds in commerce is the Saxony caviar, which is packed in linen, and is less salt than the others. The poorer Xties are pressed and salted, and sold as ‘ pressed caviar ’ or From the analyses of Gobley t and of Konig,t caviar has the following proximate composition Nitro- genous Sub- stances. N.-free Dry Substance. Water. Fat. Sub- stances, etc. Ash. N.-sub- stances. Fat. Nitro- gen. Caviar, . . 48-13 26-58 14-57 4-16 6-56 ... ... 43-89 30-79 15-66 1-67 8-09 54-89 24-02 8-78 Pressed caviar, 30-89 40-33 18-90 ... 9-88 58-36 27-35 9-36 Exarnincdion of Caviar. — W. Niebel§ gives the following as the characteristics of good caviar;—!. The colour should be grey or black; 2. The size of the eggs varies from 2 to 3 '5 mm.; 3. There should be no smell, although an acid smell is frequently * Sandbuch der Flcischkunde, p. 898. t Strohmer, Die Emahrung des Menschen, p. 143. i Nahrung Oenussmitt., ii. p. 128. § Zeit. Fleisch u. Milch Hyg., 1893, ii p. 5. 110 FLESH FOODS. to be observed in commercial varieties ; 4. Foreign substances must be absent, such as hair or sand, due to careless preparation, or oil and sago, fraudulently added. The best caviar is neutral to litmus paper, but the poorer kinds are usually acid. The latter also frequently contain traces of free ammonia, hydrogen sulphide, and free fatty acids. Preservation by Smoking. The process of smoking preserves flesh partly on account of the drying action of the heat and partly through the antiseptic action of some of the substances in the smoke, such as creosote, formal- dehyde, and pyroligneous acid. According to Marasse, the creosote in wood smoke consists of a mixture of C^Hg02, CgHjQO.2 and CgHj202. It coagulates the albumin of the meat, forming a pro- tecting envelope. The best wood for the production of the smoke is beech, while pine and fir are quite unsuitable, on account of the resins they contain. There is no loss of nutriment, such as occ\n-s in salting, and Strohmer * found that smoked meat was as digestible as fresh meat. Methods of Smoking. — There are two chief processes of smok- ing : — 1. The flesh is slowly smoked for twenty-four hours at 25° C., or in the case of sausages and fish at 70° C., and then for a short time at 100° C. ; or 2. The flesh is placed directly in the hot smoke. Ben t examined a large number of different commercial smoked meat products, and found that those prepared by the slow process contained many more micro-organisms. Intermittent smoking is had, since it favours decomposition. Action of Smoke on Bacteria. — Serafini and Ungaro t proved that smoke acts very energetically on pure cultivations of bacteria. The bacilli of anthrax and staphylococci perished in two and a half hours at the outside, hay bacilli in three and a half hours, and the spores of the anthrax bacilli after eighteen hours. On treating flesh infected with anthrax in the same manner, it was found, however, that the bacilli in the interior of the flesh did not perish, since the smoke could only penetrate very slowly on aecount of the coagulation of the albumin. Hence the conclusion arrived at was that smoking checks the development of bacteria, • but does not destroy them. Forster J met with the same experience in the case of the bacilli * Die Emahmng des Menschen, p. 135. + Ostertag, Handb. der Fltischbeschau, p. 528. + Ostertag, he. cit., p. 384. PEESERVATION OF FLESH FOODS: SMOKING. HI of tuberculosis, which he found were still virulent, after the flesh which contained them had been both salted and smoked. . Composition of Smoked Flesh.— Strohmer* gives the subjoined analyses of various kinds of smoked flesh : — Water. Nitrogenous Substances. Fat. Ash. Ham, ordinary, . . . • ,, Westphalian, . Smoked Beef, .... ,, Ox Tongue, . „ Hen-ing, 59-73 27-98 47-68 35-74 64-49 25-08 23- 97 27-10 24- 31 21-12 8-11 36-48 15-35 31-61 8-51 7-08 10-07 10-59 ' 8-51 1-24 The following analyses of smoked and salted meat and fish are taken from Konig t : — Water. Nitro- genous Sub- stances Fat. Ash. Sodium Chloride. On D Nitro- genous Sub- stances py Subst Fat. ince. Nitro- gen. Smoked Horseflesh, . 49-15 31-84 6-49 12-53 62-61 12-76 10 0-2 Westphalian Ham, . 28-11 24-74 36-45 10-54 ... 34-41 50-69 5-50 American Bacon, 9-15 9-72 75-75 5-38 ... 10-70 83-38 1-71 10-70 2-62 77-80 6-60 . . . 2-91 87-12 0-47 Smoked Goose Breast, 41-35 21-45 31-49 4-56 ... 36-57 53-69 5-85 Mackerel (mean of 4), 44-45 19-17 22-43 13-82 11-42 34-64 40-10 5-54 Herring ( ,, 3), 46-23 18-90 16-89 16-41 14-47 35-27 31-20 5-64 Salmon ( ,, 2), 51-46 24-19 11-86 12-04 10-87 49-88 24-44 7-98 Influence of Smoking on the Flesh. — During the process of pickling and smoking the colouring matter of flesh undergoes alterations, as may be observed with the spectroscope. Utescher I found that smoked ham and Hamburg smoked flesh had invariably an alkaline reaction. The Composition of American and Dutch Bacon. — Kaiser was unable to find any diflPerence in the composition of these kinds of * Die Emahrung des Menschen. t Loc. ciL, i. pp. 206 and 228. i Apoth. Ztg., 1894, p. 765. 112 FLESH FOODS. bacon. Lutz,* however, from the results of his comparative analyses, came to the conclusion that there was a considerable difference, and gave the following figures as representative of their composition ; — Water. Nitrogenous Matters. Fat. Ash. American Bacon, 9-0 9-0 71-5 10-5 Dutch Bacon 12-0 14-5 63-5 10-0 Preservation by Heat-Sterilisation and Exclusion of Air. A very large number of processes may be grouped under this head, but all are based to a greater or less extent on that devised by Appert in 1809, in which the provisions were heated in earthen- ware vessels and protected from subsequent infection by hermetic sealing. In some of the later patents the air in the vessel is replaced by an inert gas such as nitrogen or carbon dioxide, but such methods as these seem unlikely to replace the simpler ones in use. Caiuied Meats. — ^lodifications of Appert’s process have been used for the preservation of almost every description of food, but especially for fniit, meat, and fish. Cans are employed to a much greater extent than glass or earthenware, owing to their greater strength, and the readiness with which they can be made air- tiglit. In the large American factories, steam retorts are used for the sterilising, but, in the smaller factories, the cans are immersed in boiling water or in a salt bath. A small hole is left in the cover, and, after the sterilisation, and while the can is still filled with steam, this is closed with a fragment of solder. Finally, the cans are left for a week, and are then tested by striking each on the head with a wooden hammer. If the cap sinks down slowly, the process has been properly carried out, but if it is elastic and springs back, it is what is termed a * swell-head, and is rejected. Preparation of Corned Beef.— In the preparation of this, finely- divided flesh, freed from sinews and fat, is pickled in vats, and, when salted, is cooked and packed by means of steam pressure into cans, which are immediately sealed. After standing for * Jahresbcr. Nahr. Genussm., 1891, p. 40. HEAT-STERILISATION — CANNED MEATS. lio three to six hours in boiling water, the cans are pierced to allow water and fat to escape, again soldered up, and again placed in boiling water for several hours. /. n • ComposiUon of Canned Meats.— EJimg gives the following table of the percentage composition of some well-known canned meats : — Nitro- genous Sub- stances On the Dry Substance. Water. Fat. Ash. Nitro- genous Sub- stauces Fat. Nitro- gen. American meat, salted, Prepared by Wilson, . „ Canning & Co., . ,, Brougham, Australian, Pressed corned beef, . )> • 9J 5> * Mean of 10, 49-11 57-3 49-2 48-9 54- 03 51-9 57- 7 58- 8 55- 80 28- 87 28'9 25-7 27-7 29- 31 33-8 31-5 25-9 29-06 0-18 10-2 21-6 19-0 12-11 6- 4 7- 3 11-8 11-54 ( 21-07 ) A (NaCl [ 1 11-52)) 3-6 3- 5 4- 4 4-55 2- 9 3- 5 3-5 3-60 56-73 67-68 50-59 54-21 63-76 78-42 74-47 62-86 66-64 0-35 23-75 42-52 37-18 26-34 14-85 17-62 28-64 26-10 9-08 10- 83 8-09 8-67 10-20 12-55 11- 91 10-05 10-66 Tongue, Californian salmon 64-86 15-35 15-14 2-64 43-64 43-08 6-69 (mean of 3), 61-78 20-16 15-68 2-38 53-42 40-36 8-55 Warden and Bose * analysed a number of representative speci- mens of canned beef and mutton, and compared their results with the figures given by Konig for fresh meat (cf . p. 47). With seven brands of different manufacturers they obtained the following results : — Water, 49'05 to 57'35 ; fat, 10'34 to 22’08; nitrogen, 3‘93 to 4'65 ; total ash, 0'62 to 4’36 ; soluble ash, 0-189 to 4-176; chlorine, 0-112 to 2-65; phosphoric acid (P2O5), 0-308 to 0-402; potassium oxide, 0-136 to 0-434; sodium oxide, 0-117 to 0-963; extracted by boiling water, 5-35 to 10-414; and nitrogen in boiling water extract, 0-90 to 1-1 per cent. The albuminous substances (N x 6-25) in the anhydrous flesh, freed from all visible fat, are compared in a table with those of fresh meat : — * Chemical News, 1890, 71, pp. 291 and 304. H 114 FLESH FOODS, Average of Canned Beef Samples, . ,, „ Mutton, ,, Fresh Cow and Ox Flesh, ,, „ Mutton, ,, all Canned Samples, „ all Fresh Meat, Per cent. Albu- ' minous Substances. 87-06 87-19 93-94 93-81 87-12 93-87 From these analyses Warden and Bose came to the conclusion that the nutritive value of canned meat is considerably less than that of fresh meat, this difference being partially due to the salt which was present in large quantity in some of the canned meats. Sardines in Oil. — In this method of preservation the air is excluded by immersing the fish in olive oil. According to Konig the fish, from w-hich the oil has been removed by pressing it betw-een folds of filter paper, has the following composition (mean of three analyses) : — Water. Nitrogenous Substances. Fat. Ash. 53-64 25-90 11-27 9-00 On the Dry Substance. Nitrogenous Substances. Fat. Nitrogen. 36-49 28-01 6-84 Maljean* gives the following as the composition of sardines, which had been preserved by Appert’s process without the use of oil or sauce : — Water. Nitrogenous Substances. Fat. Ash. 57-50 28-40 8-07 6-03 * Rev. irUernai, des Falsi/., 1894, p. 133. EXAJIINATION OF CANNED MEATS. 115 Occasionally a red coloration of sardines, preserved in oil, may be observed. This, according to Auchd,* is due to a chromogenic bacillus, which is found in large numbers on the sardines before preservation. It is distinct from B. procUgiosus, and is non- pathogenic. The Examination of Canned Meats. — On opening the tins no gas should be found, and the jelly surrounding the flesh should be solid. If liquid, it indicates decomposition. Collection of the Gases. — The method described by Doremus T will be found suitable for the collection and examination of the gases in imperfectly sterilised goods. A hollow, bevelled steel needle is fixed in the upper arm of an adjustable clamp with its point passing through the hole of a rubber cork, which rests upon the top of the can. The upper part of the needle is con- nected by means of a capillary tube with a gas burette or nitro- meter filled with water or mer- cury. The can, which is held between the lower arm of the clamp and the rubber cork, is then punctured by turning the lower screw until the needle pierces the top. The rubber cork makes a tight joint round the needle, and the gases escape gently into the eudiometer, where they are measured and analysed in the usual way. From 60 to 80 c.c, of gas may sometimes be collected. Dore- mus states that when there is a putrid odour, carbon dioxide forms the chief constituent of the mixed gases. In other cases hydrogen predominates, there is no offensive smell, and bacteria are absent, whilst there are indications of the corrosion of the inner metallic surface. Hydrogen has also been found without dis- tinctive signs of corrosion. Occasionally the can is discoloimed, as though traces of hydrogen sulphide had been formed, and the reactions of the metals may be obtained with the contents of such tins. * Zeit. Fleisch u. Milch Hyg., 1894, p. 135. t Jour. Amer. Chern. Soe., 1897, 19, p. 730. Fig. 18. — Apparatus for collecting gases from cans. 116 FLESH FOODS. Tlie Chemical Eeaction of Canned Flesh. — According to Utescher* the flesh preserved in cans often has an alkaline reaction, without the flesh being in any way decomposed. This is noticeably the case with canned lobsters, and the point is one of considerable importance, since the alkaline liquid dissolves some of the metal from the interior of the can. To prevent this certain manufacturers line the interior with a silicate enamel, or with tough parchment paper. Poisoning by Canned Goods. — From time to time cases of illness are reported, brought on by eating canned food, though such cases are rare, if the enormous quantities of this class of food annually consumed are taken into account. When they do occur they may be due to decomposition of the flesh, through imperfect sterilisation and the consequent formation of ptomaines (c/. p. 222), or the flesh used may itself have been poisonous, as is sometinms the case with fresh meat and, more often, with fish (c/. pp. 217- 220) ; or it may be due to metal from the interior of the can, dissolved by the liquid present, or from careless soldering. Metallic Contamination of Canned Goods. — There appears to be little doubt from the work of various chemists that all kinds of canned articles are liable to metallic contamination, the degree depending to a large extent on the length of time the food has remained in contact with the metal. Van Hamel Roos f in fact advocates that no tins should he employed for the preservation of food without an interior protective lining of some description. The different metals are tested for by the ordinary quali- tative methods in the ash oVtained on calcining portions of the flesh. 1. .• j Tin. 0. HehnerJ examined a large number of tinned animal foods, and discovered tin in almost all. In a 1 lb. tin of soup the quantity was 0-035 gramme, and in presen-ed oysters (1 lb.) 0'045. In the case of hard meats the metal was found principally on the surface of the food. In some instances the interior of the can was discoloured or blackened, but in others it was still bright, notwithstanding the fact that an appreciable amount of tin had been taken up by the food. In van Hamel Roos’ communication § the occurrence and significance of this metal in preseiw-ed foods is fully discussed, with references to the results of previous workers. Kayser of Nuremberg has recorded cases of poisoning through eating preserved eels which were sub- sequently found to contain O' 19 per cent, of tin, and m * Apoth. Zlg., 1894, p. 765. t Abstract in Analyst, 1895. p. 195. X Analyst, 1880, p. 219. § Apoth. Ztg., 1894, p. 765. PRESENCE OF METALS IN CANNED MEATS. 117 a case in which 270 soldiers were poisoned by canned lettuces and meat, Bettink of Utrecht found from 0'19 to 0‘72 per cent, of tin in the food. In a tin of beef eight years old containing 970 grammes, van Hamel Boos oMained 77 milligrammes of stannic oxide, and all the other articles which he examined were more or less con- taminated. In a can of asparagus thirty-one years old, the coating of tin had been completely dissolved off the metal. 2^eaJ._When this metal is found in canned provisions it is usually derived from the solder of the can. A. Mayer * found in the ash of the meat from three tins of corned beef 0’099 gramme, 0’026 and 0'027 gramme of lead. In the Public Laboratory at Karlsruhe a slice of corned beef 1 cm. thick, weighing 145 grammes, was found to contain 0'09 gramme of metallic particles, whilst O'Ol gramme of lead was found in the ash. Similarly in a tin of bam 0-136 gramme of leaden particles were discovered. In carefully soldered tins of American manufacture, Gautier could not, however, detect any lead in the food, and the chance of its occurrence is considerably lessened by soldering the tin only from the outside. Cktpper. — This may originate from the use of copper vessels in the preparation of the food for canning, or it may have been present as a normal constituent of the food. For instance, Harvey states that in his experience copper is widely disseminated in shell-fish, and that he has always connected the delicate pink colour of the ova of salmon with the presence of a very minute quantity of copper. Hehner, too, found a small amount of copper in tinned oystei-s (c/. p. 68). Bactenological Examination of Tinned Meat. — This is carried out by the general methods given on p. 265. A simple micro- scopical examination is also of considerable importance, and note should be taken whether the muscular fibres still show their cross striations, or whether there is any coloration due to bacteria. If a large number of bacteria are observed it is probable that old or diseased flesh was used, and the presence of poisonous substances (toxalbumoses) is then not improbable. Potted Meats. — The following results were obtained by Konig and Sdllscher t in the analysis of different varieties of food pastes and potted meats manufactured by Crosse & Blackwell in 1884, * Konig, Die MenschUchen Nahr. u. Gcnussm., ii. p. 155. t Loc. cU., i. p. 233, 118 FLESH FOODS. with the exception of the imte de foie gras, which was procured from Strassburg : — Water. Nitrogenous Substances. Fat. Nitrogen- free Extractives. Ash. Sodium Chloride. P:\t6 de foie gras, 46-04 14-59 33-59 2-67 3-11 0-22 Potted beef, 32-81 17-17 44-63 3-36 2-03 ... Potted ham. 25-57 16-88 50-88 t • • 6-78 5-72 Potted tongue, . 41-52 18-46 32-85 0-46 6-71 5-98 Potted salmon, . 37-64 18-48 36-51 0-70 6-67 5-65 Potted lobster, . 51-33 14-87 24-86 4-04 4-90 0-38 Anchovy paste, . 36-81 12-33 1-59 5-18 44-09 40-10 Preservation by Chemical Antiseptics. Leaving out of the question the antiseptic substances which are employed in smoking and salting flesh preparations (salt, nitre, etc.), the number of chemical agents which have been used as meat preservatives is very large. Fresh meat and fish, potted meat, canned goods, hams, and sausages are often found to have been treated with some antiseptic or other, or with a mixture of sevei’al substances, with the object of increasing their keeping qualities. As to the advisability of this practice various opinions have been brought forward on each side. Although a preservative is a lesser evil than incipient putrefaction, there can be little doubt but that tlie continued use of food containing such substances has an injuri- ous effect on the consumer. INIoreover, in the case of meat, it would seem from Bersch’s experiments {cf. p. 122) that the treat- ment of fresh flesh with antiseptics only preserves it superficially, and lulls the purchaser into a false sense of security. From time to time the results of experiments are published showing that this or that preservative does not interfere with the action of the peptic or pancreatic enzymes in artificial digestion experiments j but such experiments do not show that the secretion of the fluids by the glands in the body is not weakened, or that the absorption of the digested substances by the system is not inter- fered with. Under the present state of affairs it is possible for a dealer to add what quantity he pleases of these antiseptics, and thus there is considerable reason for the opinion of the majority of the medical men consulted on this subject by the Lancet,* that if preservatives are to be allowed in food, it should be made compulsory for the vendor to declare the nature and amount of the compound used. * Lancet, 1897, pp. 50-60. PKESERVATION OF FLESH BY ANTISEPTICS. 119 Kammerer analysed twenty-four varieties of meat preservatives, and found they could be classified into four groups, containing 1. Common salt and nitre; 2. Sodium sulphate; 3. Boric acid or borax ; and 4. Borax and sodium sulphite. Amon«- the chemical substances which have been used or recom- mended for the preservation of flesh are the following : -Sulphur dioxide, various sulphites, bisulphites, sulphates and bisulphates ; boric acid, and various borates ; fluorides, fluosilicates, fluoborates ; chlorides (besides common salt) ; nitrates of various metals ; alum, lime, sodium carbonate, formaldehyde, chloraldehyde, acetic acid, sodium acetate, benzoic acid and benzoates ; salicylic acid, sodium salicylate, ethylidene, lactic acid, etc. Of these compounds, boric acid and borax, salicylic acid and sui- phites are the most frequently met with. Boric Acid and Borax are very widely employed for increasing the keeping properties of hams and fish. According to Jean, borated hams are extensively imported into France from England and America. To preserve fish, boric acid is used in the proportion of 2 grammes per kilo.f . . Mitscherlich has described the toxic effects of boric acid. It is a cumulative poison, and, according to le Ferd, is eliminated from the system but slowly, having been detected in the urine forty or fifty days after it had been taken.* Boric acid does not appear to interfere with the process of peptic digestion, so far as can be con- cluded from artificial experiments. J There have been numerous cases of flesh poisoning in Switzer- land through meat preserved with borates, which have not acted as complete preservatives, but have only masked the incipient putrefaction. § Detection of Boric Acid in Flesh.— KiieYm |j recommends the following method : — 10 grammes of the finely divided flesh (freed from fat as completely as possible) are warmed for about one minute with a mixture of glycerin, 2 c.c. ; alcohol, 4 c.c. ; and water (just acidified with HCl), 4 c.c. ; and the liquid filtered and tested with turmeric paper in the usual manner (brown coloration, turning black on addition of ammonia). As a confirmatory test the residue left on incineration may be moistened with sulphuric acid and methyl alcohol, the flame on ignition having a green tint in the presence of boric acid. The Determination of Boric Acid in Flesh. — The following method is recommended by C. Fresenius and G. Popp IT : — Ten * Rev. de Chim. Ind., 1897, p. 289. t Hehner, Analyst, 1890, p. 221. X Analyst, 1891, p. 126 ; Cripps, ibid., 1898, p. 182. § Jahresber. Nahr. Qenussm., 1895, p. 76. II Zeit. Fleischu. Milch Hyg., 1898, p. 188. IT Abstract, Analyst, 1897, p. 282. 120 FLESH FOODS. grammes of the finely divided substance are triturated in a mortar with from four to eight times the quantity of calcined sodium sul- phate, the mass heated on the water-bath, and, when dry, finely pulverised after the addition of more sodium sulphate. It is then digested m 100 c.c. of cold methyl alcohol for twelve hours, with frequent shaking, and the alcoholic extract distilled. As a rule the whole of the boric acid passes over with the alcohol, but it is advisable to repeat the extraction and distillation, using 50 c.c. of methyl alcohol. The distillates are made up to 150 c.c. with methyl alcohol, and the boric acid determined in 50 c.c. by adding 75 c.c.- of water and 25 c.c. of pure glycerin, and titrating with N /20 sodium hydroxide solution, with phenol-phthalein as indicator. As soon as a pale rose coloration is obtained more glycerin is added, and if the colour disappears the titration is continued. The number of c.c. of alkali used, multiplied by O'OOSl, gives the quantity of boric acid (H3BO3) in the liquid titrated. If borates are also present in the substance they should he left in the residue from the distillation, and can usually be extracted with methyl alcohol from the mass after incineration. 0. Hehner * mixes the substance with methyl alcohol acidified with sulphuric acid, and collects the boric acid distilling over with the alcohol, in a solution of sodium phosphate of known strength, evaporates the liquid to dryness, and weighs the residue. K. Thaddiief t recommends a gravimetric method, in which the boric acid distilled over with methyl alcohol is fixed and weighed as potassium borofluoride. The distillate is received in a platinum basin containing a 10 per cent, solution of pure potassium hydroxide, and when four successive portions of 10 c.c. of methyl alcohol have distilled over is concentrated to half its volume on the water-bath. An excess of pure hydrofluoric acid is then added, and the evaporation continued until only a faint smell of hydro- fluoric acid is perceptible. When cool, 50 c.c. of a solution of potassium acetate (sp. gr. 1‘14) are added, and the basin allowed to stand for one or two hours, its contents being frequently stirred with a platinum rod. The insoluble substance is collected on a weighed filter paper, which has previously been moistened with alcohol and dried at 100° to 110° C. The filter and its contents are washed with alcohol of specific gravity 0'805, of which from 62 to 72 c.c. are usually required, and are then dried at 100°to 110° C. for three hours and weighed. Sulphur Dioxide and Sulphites. — Sulphurous acid and its salts are very widely employed in the preservation of meat products, and enter into the composition of very many of the meat preserva- * Analyst, 1891, p. 142. t Zeit, anal. Chem., 1897, pp. 568-637. PRESERVATION BY SULPHUR DIOXIDE AND SULPHITES. 121 tives with fanciful names now in the market. They all have a powerful germicidal action. ^ As to their physiological action various statements have been made. Polli* found that 8 to 12 grammes of sulphites were not injurious to adults, while others found that children could take 1’8 gramme per day without ill effects. On the other hand, 1 gramme of magnesium sulphite has been found in certain casp injurious to women, causing disorders of the stomach (Bernatzik and Braun). As an instance of the extent to which flesh preparations are treated with sulphurous acid and sulphites, it may be mentioned that Fischer t found that 50 per cent, of the preserved meat pro- ducts (sausages, etc.) sold in Breslau in 1895 contained sulphites, the quantity of sulphur dioxide in the meat varying between O'Ol and 0'34 per cent. Action of Sulphurous Acid on Flesh. — Sulphurous acid and its salts, especially calcium bisulphite, appear to have a considerable action on muscular fibre, altering the normal condition of the flesh. According to A. Riche, J this action proceeds at the ordi- nary temperature, and causes changes in the soluble proteid substances. An addition of 1 per cent, of a sulphite to the flesh is not per- ceptible either to the taste or smell. On cooking the flesh the sulphite is only partially decomposed and expelled. Detection of Sulphurous Acid. — To detect sulphur dioxide in flesh H. K am merer § places a sample on a moist strip of potassium iodate starch paper, and moistens the flesh with sulphuric acid (free from oxides of nitrogen). In the presence of sulphites a pronounced blue colour is immediately obtained, whilst pure flesh only gives at most a feeble coloration after a considerable time. Salted flesh or flesh containing nitre cannot be tested in this way, since by the action of the sulphuric acid substances are set free (HCl, and nitrous acid from nitrites present in the nitre), which liberate iodine from the iodate. In many cases it is possible to recognise the smell of sulphur dioxide on simply mixing the flesh with dilute sulphuric acid (1 : 8). Kammerer found in the mean 0'0512 gramme of sulphur dioxide, and 0'1016 gramme of sodium sul- phite in 100 grammes of preserved flesh. Estimation of Sulphurous Acid in Flesh. \\ — A weighed quantity of the finely divided flesh is mixed with phosphoric acid, and dis- tilled in a current of steam or carbon dioxide, the distillate being * Ostertag, Handhuch der Fleischbeschau, p. 530. t Forschungs Ber., 1897, p. 26. X Joum. Pharm. Chim., 1897. § Forschungs Ber., 1896, p. 257. 11 B. Fischer, Jahresher. Nahr, u. Genussm., 1895, p. 76. 122 FLESH FOODS. collected in an apparatus containing an excess of iodine solution. After the distillation the sulphuric acid in the distillate is precipi- tated with barium chloride in the usual way. According to Fischer, all flesh containing more than 0-1 per cent, of sulphur dioxide must be regarded as injurious to health. Salicylic Acid is one of the constituents of many of the so-called ‘meat-preservatives,’ although in the case of fresh meat, at any rate, its action appears to be purely superficial. Bersch placed a, portion of the flesh of a recently -killed animal in a concentrated aqueous solution of salicylic acid, and found that after four days the exterior of the meat was perfectly sound, whilst the interior showed unmistakable signs of putrefaction, and contained a large number of micro-organisms. Hence he came to the conclusion that the preservation of fresh raw meat by salicylic acid and other ordinary chemical antiseptics was not practicable. In flesh pre- parations such as sausages and potted meat, in which the salicylic acid can be distributed throughout the mass, its germicidal pro- perties would obviously be more distributed. But on account of its marked taste it cannot be used in such quantity in meat preparations as in some other food substances in which the flavour is concealed. With regard to the influence of salicylic acid on the human subject there are diverse opinions, but it is significant that the Paris Academy of Science forbid even the smallest addi- tion of salicylates to food as being liable to cause injury where any weakness of the kidneys or digestive organs exists. Detertiun and Edimation of Salicylic Acid in Flesh. — The finely-divided flesh is distilled with steam, and the last portions of the distillate tested with ferric chloride (violet coloration). For the estimation the substance is dried, finely pulverised, mixed into a paste with dilute sulphuric acid and extracted with ether. The ethereal extract is evaporated to dryness, and the residue taken up with water and distilled. The free salicylic acid in the distillate is determined by titration with standard alkali, either litmus or phenol-phthalein being used as an indicator. The violet coloration given with iron salts may also be employed for the color! metrical estimation of salicylic acid in the final dis- tillate, the colour obtained on the gradual addition of a very dilute solution of ferric chloride being compared with that given by an aqueous solution of a known quantity of the acid. An additional test for salicylic acid is to warm portions of the meat product with methyl alcohol and sulphuric acid, when, in the presence of the antiseptic, the characteristic odour of methyl salicylate will be observed. * Die Conservirungsmittd, p. 86. PRESERVATION BY FORMALDEHYDE. 123 Foi-maldehyde.— During the last few years this powerful anti- septic has been tried for the preservation of every description ot food, and although its application has not been very successful in the case of flesh, it is still met with in various meat preservatives. ‘ Carnolin,’ for instance, consists of a I’S per cent, aqueous solution of formaldehyde slightly acidified. i The ettects of the continued use of ‘ formalin on the Human system have not yet been clearly determined, but its power of forming insoluble compounds with proteid bodies, and its harden- incT influence on animal tissues, must of necessity render meat treated by it much less digestible if not altogether uneatable. Mabery and Goldsmith* found that 0 '2 gramme of formaldehyde interfered with the artificial peptic digestion of blood fibrin. Effect on Meat and Fish, — E. Ludwig f states that formalin is not applicable to the preservation of meat products. Ehrlich | tried the effect of an 8 per cent, solution of formaldehyde on various food substances. He found that horse-flesh was com- pletely preserved by it, but that the odour developed was so un- pleasant that the meat could not be eaten. Beef treated with the solution was equally preserved, and did not develop this charac- teristic smell, but, on the other hand, the meat was only fit to be eaten for a short time after the addition of the preservative, on account of the chemical changes caused by it. According to Bloxam,§ fish treated with formaldehyde beconies so hard as to be unsaleable, even when the preserving solution only contains 1 part in 5000. The Detection of Formaldehyde. — The finely-divided meat product is mixed with water and distilled, and the distillate tested for the preservative. A very large number of tests have been described, of which the following are a selection : — 1. A drop of milk is added to the distillate, and the mixture poured carefully down the side of a test-tube containing strong sulphuric acid, with a trace of ferric chloride. A blue ring appears at the zone of contact of the liquids in the presence of traces of formaldehyde (but only with traces). Acetaldehyde does not give this reaction (Hehner).ll 2. One drop of a dilute aqueous solution of phenol is added to the distillate, and the mixture added to strong sul- phuric acid, a bright crimson ring appearing at the line of contact, in the presence of formaldehyde. This coloration is perceptible in solutions containing 1 part * Jour. Amer. Chem. Soc., 1897, p. 889. + Zeit. Fleisch u. Milch Hyg., 1894, p. 193. J Ibid., 1898, p. 232. § Analyst, 1895, p. 167. II Ibid., 1896, p. 96. 124 FLESH FOODS. of formaldehyde in 200,000. If more than 1 part in 100,000 be present, a -white milky zone appears above the red ring, while in still stronger solutions a pink curd-like precipitate is obtained. Acetaldehyde, under the same conditions, gives an orange-yellow coloration (Hehner).* 3. Nessler’s reagent mixed with solutions of formaldehyde gives a browm coloration, or precipitate, which gradually darkens and finally becomes dark grey. This reaction, which is not given by acetaldehyde, will detect a very minute trace of formaldehyde (Mitchell), t 4. The distillate fioated on an equal volume of a solution of O'l gramme of morphine hydrochloride gives a reddish violet colour in a few minutes, if formalin be present in greater quantity than 1 : 6000 (Keutmann).J 5. Several drops of a 10 per cent, solution of phloroglucinol are added to 10 c.c. of the distillate, the mixture shaken, and a few drops of a solution of potassium hydroxide added. A red colour is obtained in a solution containing as little as 1 part of formaldehyde in 20,000 (Jorissen). § The Estimation of Formaldehyde. — Owing to its power of com- bining with proteid substances to form insoluble non-volatile compounds, it is practically impossible to determine the exact amount of formalin added to a meat product, and the amount obtainable by distillation decreases with the lapse of time. One of the simplest methods of estimating formaldehyde in an aqueous solution is based on the fact that it combines with ammonia to form hexa-methylene-amiue — 6CH2O -F 4NHg = (CH2)gN4 + GHgO. A known volume of the solution is shaken in a stoppered bottle with an excess of standard ammonia, the bottle allowed to stand for several hours, the uncombined ammonia distilled OA'er into standard acid, and the latter titrated back. A correction is made for the acidity of the solution previously determined by titra- tion with standard alkali. H. Smith describes a method of determining formaldehyde by oxidation wdth potassium permanganate, |1 and Romijn discusses the accuracy of the various methods of estimation, and describes two new processes.il See also a paper by R. Orchard (^Analyst, 1897, p. 4). ■* Analyst, 1896, p. 96. i rbid., 1897, p. 106. 11 Ibid., 1896, p. 148 ; 1897, p. 5. f Ibid., 1896, p. 98. § Ibid., 1897, p. 282. II Ibid., 1897, p. 221. CHAPTER VII. THE COMPOSITION AND ANALYSIS OF SAITSAGES. In this country only two or three kinds of sausages are naanu- factured, but on the Continent, and especially in Germany, where the sausage may be regarded as a national dish, there are many varieties prepared by different recipes. German Sausages. — The chief kinds of German sausages, as describedbyKonig* and by Merges, t are:— _ Red Sausage {Rothwurst, Buntwurst). — Pork is boiled for about three-quarters of an hour, flavoured with salt, pepper, pimento, etc., and after admixture of not too great a proportion of warm fresh blood, placed in the skins and boiled. The English black puddings have a similar composition. Magenwurst. — This is very similar in composition to rotJmurst, but contains less blood and rather more fat. The sausage mass is finally packed in a cleansed pig’s stomach. Zungemourst is composed of tripe, pig’s head, and fat pork from a young pig, finely minced and mixed with a small quantity of pig’s liver and some pig’s blood. Blutiourst is composed of bacon and pork, sometimes with the addition of heart and kidney, and with or without flour. It is mixed with about an eighth of its weight of fresh pig’s blood, and boiled. Lungenhlutwurst differs from the preceding sausage in contain- ing finely minced lung. Lebenourste, or Live7- Sausages, are prepared from pigs’ or calves’ livers, thoroughly cleansed from blood, and mixed with a certain proportion of lard and pork, and cooked. The constituents and the proportions vary in the different kinds of liver sausage, such as Mecklenburg leberwurst and Brxmswick leberwurst. Gehim, or Brain Sausage, consists principally of calves’ brains and pork. * Die Menschlichen Nahr, u. Oenussm., ii. p. 161. t JVurst und Fleischwaaren Fabrikation. 126 FLESH FOODS. PressTcopfwurst is largely composed of pickled and boiled pig’s head. Mosaik Sausage is a mixture of pork and beef, with spices, etc. Ahfallblutvmrst is made from sinews and butchers’ refuse, with bacon and pig’s or ox blood. Sclmartemcurst and Sulzemourst consist of lightly cooked un- salted ham, together with skin, etc., boiled soft, and a little blood. Bratwurst is prepared from fresh raw pork and ham, with salt, pepper, etc., and sometimes contains lemon-peel or cumin. Cervelatiourst is prepared from pork and lard, often with the addition of beef or horse-flesh. This sausage is often coloured with fuchsin. The Italian Salamiwurst is manufactured from beef or pork, and is coloured with red wine. Knackwurst, or cracking-Sausage, is a hard, smoked sausage, about 15 cm. in length, with the same composition as cervelat- wurst, but differing in the flesh being previously cooked. Its name is derived from the crackling sound on breaking the sausages apart. Knohlauchwurst, or Garlic Sausage, has the same composition as the preceding sausage, with the addition of garlic. Frankfort or Vienna Wiirstclien are small sausages about the length of a finger, composed of raw, lean pork, seasoned with salt, pepper, etc. Frbsicurst consists of a mixture of beef-fat, bacon, pea-meal, onions, salt, and seasoning. The pea-meal is prepared by a patent process to prevent the development of acidity. These sausages formed a principal part of the rations of the German troops in the Franco-German war. The Table on p. 127, taken from Konig’s larger list, gives the composition of some of these varieties of sausages. EngUsb Sausages. — The best kinds of sausages sold in this country are prepared from raw meat, suitably flavoured with spices, and frequently incorporated with a small proportion of bread-crumbs. In poorer districts, however, the amount of bread or powdered biscuit often exceeds that of the meat. A remark- able instance of the extent to which this practice has been carried on was revealed in a recent case in the law courts, in which a baker admitted that the sausages from which he made his sausage- rolls contained no meat at all, but were prepared from bread coloured with red ochre, and seasoned. The innumerable varieties of sausages met with in Germany are not manufactured in England, where sausages are usually described by the name of the meat they contain. COMPOSITION OF GERMAN SAUSAGES. COMPOSITION OF GERMAN SAUSAGES. 127 On the Dry Substance. Nitrogen. 4)iu3eoOT'^'^eoco«3ooo»COCOCOOO'^.t^CO t^t'^5O’^00C0'^t>»00'7»0500OrH(»’^O00 ^^^,lH05\r500iCO(MiOCO(N r-l(N^i— C C > n • 29-16 > ” From these results Bujard concludes that only in ex- ceptional cases (where the amount is large) can the glycogen be taken as conclusive of the presence of horse- flesh, especially when the latter is mixed with other kinds of flesh. _ 1 j-j! If we take into consideration the results of these dif- ferent chemists, the reaction of glycogen with iodine and the quantitative determination of glycogen must be re- garded as giving uncertain conclusions as to the presence of horseflesh. Apart from the fact that glycogen appears normally in certain organs of other animals, it has been shown that its formation and distribution throughout the body is influenced by tbe food given to the animal, and also that the quantity is subject to considerable variation in certain diseased conditions. On the other hand, in old sausages the glycogen may undergo decom- position, and a negative result be obtained with the tests, when horseflesh is actually present. Hence the results obtained by these and similar methods must only be taken as corroborative evidence. V. The Form of the Fat CeZZs.— According to Jungers* the fat cells of the different animals used for food show * Jahresber, Nahr. u. Genussm., 1894, p. 64. 140 FLESH FOODS. distinct differences in external form, which are especially marked in the case of the horse. This difference can also be observed in the fat cells of apparently fat-free flesh, and can be used for the detection of horseflesh in mixtures. In boiled and smoked sansages, however, it is only possible to find unaltered fat cells by taking the test from the centre of the sample. The nature of this characteristic difference is not described, vi. Examination of the Fat. — The fat extracted by one of the methods given on p. 83 is examined by the usual methods, and the results compared with the figures of the constants in the tables on pp. 52-59. Crystallisation from Ether. — When the sausage is com- posed entirely of pork the fat on crystallisation from ether will, as a rule, give the characteristic chisel-shaped crystals. Horse fat, on the other hand, is very soluble in ether, but by using very small quantities of solvent, crystals resembling those of beef stearin (pp. 50 and 58) can be obtained. Iodine Value. — Since the mean iodine value of beef fat is about 55, whilst that of horse fat is about 83, a determination of this constant is valuable when the sausage is composed of only one of these kinds of flesh, which, however, is not often the case. R. Friihling,* in his experiments on this point, deter- mined the iodine value of the fat from different sausages. The finely divided substance was boiled for a consider- able time with water, and after cooling, the layer of the fat on the surface of the liquid was removed, filtered, and its iodine value determined by Hubl’s method. The results obtained with the fat thus extracted were : — Iodine Value. Sausage made from pure horseflesh 72'5 consisting of horseflesh with 15 per cent, of pork, . 62 ‘3 „ n 50 „ . 57-2 Since lard has an iodine absorption of from 56'9 to 63‘8 (Benedikt), it is obvious that this method w^ould lead to no certain conclusion in the case of mixtures. Examination of the Intermuscular Fat. — The fat within the muscular fibre was first examined by Nussberger.f The fat was extracted from the muscle of various kinds of horseflesh (kidneys, ham, etc.) by means of ether, and iodine values of from 80 to 94 obtained, the mean being * Zcit. angew. Chem., 1896, p. 352. t Chem. PMudschau, i. p. 61. HORSEFLESH IN SAUSAGES— EXAMINATION OF FAT. 141 84. The iodine values obtained were probably too low on account of the presence of other substances, besides fat, extracted by the ether. Bremer* carries Nussberger’s method a step further, and determines the iodine value of the more fluid of the fatty acids obtained from the intermuscular tat. The sausage mass, from which all visible fat has been removed, is finely minced, mixed with water, and heated for about an hour on the water-bath. The fat rising to the surface is poured away with the water, and the flesh, after having been washed several times with hot water, is dried at 110° C. for twelve hours, and extracted for several hours with a petroleum spirit of low boiling- point. Part of the intermuscular fat thus obtained is used for the determination of the iodine value, refractive index, and Reichert-Meissl value. The remainder is saponified, the excess of alkali neutralised with acetic acid, and the alcohol evaporated on the water-bath. The soap is dissolved in hot water, the liquid fatty acids separated as zinc salts by Jean’s method (p. 98), and the iodine value of the soluble zinc salts, or^ of the acids liberated from them, determined as described on page 99. The following table gives the results which Bremer obtained : — 1. Horseflesh sausage without bacon, . 2. , ,, with about 6 per cent, of bacon, 3. Horseflesh sausage with about 22 per cent. of bacon well smoked, 4. Horseflesh cervelat sausage with about 69 per cent, of bacon, .... 5. Ordinary sausage with some bacon, . 6. Thuringian cervelat sausage with about 65 per cent, of lard, .... 7. Mixture of 1 and 5 in equal parts, . 8. Mixture of 4 and 6 in equal parts, . Iodine value Iodine value of inter- of liquid acids muscular fat. of the fat. 75-8 108-1 74-0 104-1 53-7 92-4 74-1 102-1 57-6 94-2 64-3 95-8 66-4 103-1 65-2 99-5 Bremer also found that when horseflesh was present the petroleum spirit extract had a red to reddish-brown colour, and that even the liquid fatty acids had a more or less pronounced reddish-yellow shade. On the other hand, bull’s flesh gave a similar colour, so that this fact can only be used as a confirmatory test. When, * Forschungs Ber., 1897, iv. p. 5. 142 FLESH FOODS. however, this coloration is obtained, when at the same time glycogen is detected, and when the iodine number of the intermuscular fat exceeds 65, and that of the liquid fatty acids is considerably over 95, there can, in Bremer’s opinion, be but little doubt as to the presence of horseflesh. The Artificial Coloration of Sausages. — Sausages are artificially coloured either with the object of concealing an addition of starch or bread, or of improving the colour of the meat, and in some cases disguising its condition. "Vl’lien fresh beef is exposed to the atmosphere it soon changes its colour, and the bright red, due to the oxyhsemoglobin, becomes dark brown and eventually yellowish- brown or grey. Similar alterations take place in lighter coloured flesh, such as veal and pork, though they are not so pronounced as in beef. When the exposed meat is in the finely-minced state in which it is used for sausages, these changes occur with great rapidity. When decomposition, whether of an acid or alkaline nature (c/. pp. 74-76), has commenced, the surface of the meat often assumes a bluish or greenish tint. On being heated to 70° or 80° C. the hremoglobin of the flesh is decomposed, and haematin, which has a brown colour, is formed. Hence red flesh (beef, mutton) becomes dark brown on cooking, while the lighter coloured meats (e.y., veal, pork, and fowl), which contain comparatively little haemoglobin, do not show this change in colour, but become grey. In order to regain the original colour many sausage mamv facturers are in the habit of adding a trace of some colouring matter such as cochineal, carmine, or an aniline dye, and this has been a common practice in Germany for the last fifty years. Lately, however, the question has received considerable attention, and there is a growing opinion that since the practice offers great facility for disguising unsound flesh, it ought to be altogether forbidden. As an instance in point it may be mentioned that H. Bremer * recently met with a cervelat sausage coloured with carmine, which when cut had all the appearance of sound flesh, but on further examination was found to be quite unfit for food, the acid value of the fat being 76'0. The Microscopical Detection of Colour. — G. Marpmann t recom- mends the following method of examination A section of the sausage, about 1 cm. thick, is thoroughly moistened with 50 per cent alcohol, and examined under the microscope. When only traces of colouring matter are present, the substance is dehydrated in xylol, which is expelled by means of carbon tetrachloride, and the mass placed in cedar oil. As thus prepared it is transparent, * Forsehungs Ber., 1897, 4, p. 45. t Zeit. angeio. 3Iikrosk., 1895, p. 12. artificial coloration in sausages. 143 and colouring matters present can readily ^^n^ed Fuch^^^^^ centrated solution. The finely divided sausage is P cent, alcohol, the liquid (freed frorn fat) evaporated to a and some undyed sausage placed in this solution. Th fibrer^d the fet cells are then stained deeply. Marpmann states tLt safranin is largely employed for > CO a; 302 G <£> G «J 0) — M o> G rdlp :G0 M o rG n! o o G o o G o ;zi •G a CO > o O o 3a (£) 03 G a G blD to W 0> CO o 'd 4 §1 Cm rG o .s 'Hd ^ :G G . ci CO “= ^ M O pqQpL,o2EO o G G o O ■T3 G cO rO o cd pG rG pG cd a o s G 5 o5 .2 s*S \n O G 1^ CO CO 05 CO CO 0 rH 05 Ash. 1>- Tt! 1— • CO (N lo CO CO : : (N »p fX> • rH O rH 0 0000 rH 0 ?H 0 O i-( 05 Phosphorus. : * ' * * rH 0 CO O CO 00 0 CO 00 CO 05 0 0 Oxygen. f—t o> (N (N 0 00 CO 10 . rH (N CN (N CO CO . iH lO rH 0 05 00 rH rH rH 0 . 00 CO CO 05 rH CO rH CO 05 00 G CO UTi Id CO lO CO 0 CO CO l-N. CO CO iO io CO CO rH 1-H rH rH rH i-> rH rH ^ rH r^ ?H rH rH rH tH iO 00 00 rH rH O CO CO CQ 00 0 G rH (N CO Hydrogen. 00 Ci rH O 05 05 00 CO CO 00 ^ 0 00 (N 0 (X> CD CO t-- 1:0 CO CO ^ CO t'- 1>* CO CO CO m CO 05 f-H CO CO 00 0 rH 0 0 CO CO 10 CO Carbon. o CO 00 J>- 05 CO CO 00 t>» CO CO 05 CO CN rH CO fN (M (M (M (N (N CO 0 0 (M 05 (N urs lO iO lO 10 »o UO G G G 0 lO iO u*5i •« c d' . . G • • G .G • * • M G G ‘o -4-3 o u* Ph a G pG cd a albumin a G jG **? 6 .a" *OT G ^ G © G bJO 0 0 w).3 P4 © Hid a fsa :2 s [i.OOS!2iO cd s fH © H-9 0 «2 M PhP.:. 0 0 w CL, * Medical Record^ 1894, p, 450. 150 FLESH FOODS. CLASSIFICATION Gkoup I. Albuminous Substances. Gkocp 11. Compound Albuminous Substances. 1. Soluble in tcater. Coagulable by heat or long contact with alcohol. Albumins : Egg albumin. Serum albumin. Muscle albumin. Plant albumins, etc. 1. Compounds of a proteid with an iron- containing pigment. Soluble in water, and coagulated by heat and alcohol. Haemoglobin. Oxy haemoglobin. Methoemoglobin. 2. Iwmluble in water, but soluble in salt solutums. More or less coagulated by heat. Globulins : a. Soluble in dilute and saturated solu- tions of sodium chloride. Vitellins. b. .Soluble in dilute solutions of sodium chloride, but precipitated on satura- tion with that salt. Egg globulins. Serum globulins, lacto-glohulin. Cell globulins. Fibrinogen. Myosin, etc. 2. Compounds of a proteid with a mem- ber of the carbohydrate group. In- soluble in water. Soluble in very weak alkalies. Mucins. Mucoids. 3. Compounds of a proteid with nucleic acid. Phosphorised bodies yielding on decomposition metaphosphonc acid. Insoluble in water and acid pepsin solution, but more or less soluble in alkalies. Nucleins. 3. Insoluble in water and salt solutions. Soluble in dilute alcohol. Albuminous substances chiefly of vegetable origin : Zein, Gliadins. 4. Compounds of proteids with nucleins. Very soluble in dilute alkalies. Nucleo-albumins of cell-proto- plasm. Cell nuclei, etc. Caseins. 4. Insoluble in water, salt solutions ami alcohol. Soluble in dilute acids a?id alkalies. a. Coagulated by heat, when suspended in a neutral fluid. Acid albumins ; Syntonin, and the like. Alkali albumins ; Albuminates. b. Not coagulated by heat in a neutral fluid. Glutenins. 6. Amyloids. 6. Insoluble, or nearly so, in water, salt solutio7is,andalcohol. Soluble in strong acids and alkalies, and in add pepsin and alkaline trypsin solutions. Coagulated albuminous substances ; Fibrin. Coagulated white of egg, etc. 6. Histones? SYSTEMATIC CLASSIFICATION OF PROTEIDS. 151 OF PROTEIDS. Gkoup in. Albuminoid Substances. Class I. Structural Substances. Class II. Derivatives of Albuminous Substances. Proteoses, Peptones, etc. Class III. Enzymes. 1. Soluble in boiling water, and yielding on decompo- sition leueine and glyco- coll. Collagenes : Gelatin. Glue, and the like. 2. Insoluble in boiling water. Yielding on decomposi- tion much tyrosine, vyith leucine and glycocoU. Slowly hydrated by boil- ing dilute acids and by pepsin with HCl. Elastins. 1. Soluble in water. Not coagulated by heat or alcohol. a. Proto- and Deutero- proteoses : Protoalbumose. Deuteroalbumose. Globuloses. Elastoses. Myosinoses. b. Peptones : Amphopeptones. Hemipeptbnes. Antipeptones. 2. Insoluble in water. Soluble in dilute salt solutions. Precipitated by saturation with NaCl. 1. Proteolytic; Pepsin. Trypsin. Papayotin, and the like. 2. Amylolytic: Diastase. Invertin, and the like. 3. Fat- Decomposing En- zymes; Steapsin, and the like. 3. Insolvllein water, dilute acids and alkalies, and in acid pepsin and alkaline trypsin solutions. On de- composition yield leueine and tyrosine. Keratins. Neurokeratins. Hetero-proteoses : Hetero-albumoses. Hetero-globuloses. Hetero-myosinoses, etc. 3. Insoluble in water, salt solutions^ and alcohol. Soluble in dilute acids and alkalies. Dysproteoses. Antialbumids. i. Glucoside ■ Decomposing Enzymes. 6. Amide - Decomposing Enzymes: IJrase, and the like. 6. Coagulating Enzymes; Rennet, and the like. 152 FLESH FOODS. Albumins, of which egg albumin may be taken as the type, are soluble in water, and coagulate on heating. Egg albumin coagu- lates at about 72° C., and has a specific rotation of -35’5. When white of egg is dried at 100° C. it loses about 88 per cent, of its weight. In preparing ordinary commercial albumin, white of egg is evaporated at a low temperature, leaving light yellow flakes. Or sometimes the fibrin, which is also present in small quantity, is previously removed by beating and filtering through a cloth. Globulins are closely allied to albumins, but differ from them in their behaviour towards salt solutions. They dissolve in dilute solutions of sodium chloride, but are as a rule precipitated by saturating the liquid with sodium chloride or magnesium sulphate. The Vitellins, of which representatives are found in egg-yolk and in the eyes of fish, differ from the globulins proper in not being precipitated by saturation with sodium chloride. Acid Albumins. — These are compounds of hydrochloric or acetic acid with an albumin or globulin. They are produced as the first stage in the hydrolysis of these substances by means of pepsin. Myosin, for example, in the digestive process first forms an acid albumin or syntonin. Like globulins, they are precipitated by saturating their solution with sodium chloride or magnesium sulphate. Alkali Albumins or Albuminates are produced by the action of alkalies on albumins or globulins. They are soluble in alkalies, but not in neutral liquids. Coagulated Albumins, — Under the influence of heat, or long contact with alcohol, or in some cases by the action of enzymes, albuminous substances become converted into a peculiar modifica- tion which is exceedingly insoluble. Types of these are coagulated white of egg and fibrin from fibrinogen. The temperature of heat coagulation varies with the nature of the salts in the liquid and with the concentration of the solution (c/. p. 162). It is curious that coagulation cannot be brought about by boiling a solution of an albuminous substance to which a trace of formaldehyde has been previously added. Compound Albuminous Substances. These consist of proteids, whose molecule is composed of a simple albuminous substance in combination with another sub stance often of a non-proteid nature. Hsemoglobins. — In the hmmoglohins there is a colouring matter group which contains iron (see p. 37). ALBUMINOID SUBSTANCES. 153 Mucins. — Mucins and Mucoids are representatives of compounds of albuminous substances with a carbohydrate. Mucins are found in secretions of various glands and on the skin of the snail. They can be precipitated from their solutions in the absence of salts by means of acetic acid or a mineral acid. The precipitate is insoluble in an excess of acetic acid, a property which is made use of in the separation of mucins from albumins. According to Neumeister they have the following composition : nitrogen, 11-7 to 12-3; carbon, 48-3 to 48-8; oxygen, 31-3 to 33-6 ; and sulphur, about 0’8 per cent. By long-continued boiling with dilute mineral acids, or by the action of superheated steam, mucins are converted into syntonins and eventually peptones, while substances of a carbohydrate nature are liberated (c/. p. 24). Mucoids are closely allied to mucins. They have been isolated in small quantity from the white of birds’ eggs, and from the cornea of the eye. Hyalogens are substances which are often grouped with the mucoids. By the action of dilute potassium hydroxide, they are converted into very insoluble substances known as hyalins. Hyalogens are found in the skin of the serpent and in the bladder of the echinococcus (c/. p. 243). Nucleins. — The composition of a representative nuclein is given in the list on p. 149. See also p. 6. Albuminoid Substances. I. — Structural Substances. Collagene is a widely distributed substance, forming, as it does, a principal part of the connective tissue and the organic substance of bone. In Neumeister’s opinion it is probably produced in the animal system by the decomposition and oxidation of albuminous substances. Its mean composition is: — Carbon, 50’75; hydrogen, 6’47 ; nitrogen, 17-86; oxygen, 24‘32; and sulphur, 0-6 per cent. Collagene, unlike the albuminous substances, does not yield tyrosine on hydrolysis, the end products of the decomposition brought about by boiling hydrochloric acid being leucine, aspartic acid, glutamic acid, and glycocoll. The sulphur, which it contains, appears to be in a much closer state of combination than is that of albumin. Gelatin. — When collagene or substances containing it are boiled with water, the collagene is hydrated and dissolves in the form of 154 FLESH FOODS. gelatin or glue, the latter being an impure gelatin. The elementary composition of gelatin is shown on p. 149, and the composition of the first products of its hydrolytic decomposition on p. 181. Gelatin is not precipitated by mineral acids, by potassium, ferrocyanide with acetic acid, or by salts of lead or copper. It is, however, precipitated by most of the other reagents for pro- teids. Bromine or chlorine precipitate it quantitatively, and it combines with tannin in the presence of salt to form a char- acteristic insoluble compound (leather). Mercuric chloride pre- cipitates it in the presence of hydrochloric acid. Gelatin undergoes hydrolysis with great readiness. On boiling it for a short time with very dilute acid, or for a long time with pure water, it loses its gelatinising power through its conversion into gelatose. Elastin. — This proteid is the main constituent of the elastic tissue. In the analysis of its elementary composition (p. 149) sulphur is given as one of its constituents, but later analyses of pure elastin have shown that it does not contain sulphur. It can be brought into solution by treatment with superheated steam, or by boiling it for several hours with dilute mineral acids or strong alkali (<•/. p. 24). Keratins are found in such parts of the animal system as the hair, horns, nails, and feathers. They contain a large proportion of sulphur (from 3 to 5 per cent.), while the oxygen is less than that of true albuminous bodies. They are remarkably insoluble, but can be brought into partial solution by the action of super- heated steam or by boiling with alkali. II. — Derivatives of Albuminous and Structural Albuminoid Substances. Proteoses. — This word is used as a convenient generic term for certain products of the hydrolysis of native proteids in which the decomposition, whether brought about by acids, superheated steam, or proteolytic enzymes, has only proceeded to a certain extent. Thus it includes the albumoses, derivatives of albumin ; fibrinoses from fibrin ; caseoses from casein, etc. Not unfrequently, however, all such products are termed ‘ albumoses,’ since the latter have received the most study, and may be regarded as typical proteoses. Albumoses. — For the want of more accurate knowledge we group together under this name a large number of albuminous derivatives with a few characteristics in common. Further sub- division can be effected into groups which behave differently with different solvents ; but proteolysis is not a simple process, and at any given stage of the decomposition each group contains sub- ALBUMOSES. 155 stances with ever-varying composition, until finally, with the con- tinuation of the hydrolysis, the products are gradually broken up into substances of a simpler composition, lower molecular weight, and greater solubility, which can be grouped together as peptones. _ . , This is doubtless the reason why in many analyses ot meat extracts, peptones have been found by one chemist and not by another. For instance, in methods of analysis in which alcohol is used as the precipitating agent, those products which are most soluble, or, in other words, require the greatest addition of alcohol for their precipitation, are returned as peptones ; whereas, if satu- ration with zinc sulphate were used, they might be partially precipitated together with the derivatives more closely related to the original proteid, and be classed with the albumoses. Old Names for Albumoses. — Some confusion has also been caused by the fact that formerly all the products of peptic digestion were called peptones. When a differentiation between the higher and lower products had been effected, Kiihne gave to the former the name of propeptones, while Meissner termed them a-peptones. Eventually the name albumoses was adopted by Kiihne. Genen-al Properties. — Albumoses differ from native albuminous substances in being much more soluble, and in not being coagu- lated by heat or by alcohol, though they can be precipitated by the latter. They contain less carbon, but more oxygen, and have much lower molecular weights. They are slightly diffusible, while albumin proper is completely indiffusible. Like the native proteids they are precipitated from their aqueous solutions by saturation with zinc sulphate or ammonium sulphate. They can also be precipitated by chlorine or bromine, nitric acid, mercuric chloride, phosphotungstic acid, tannic acid, picric acid (primary albumoses), trichloracetic acid, and less readily by a solution of mercuric iodide and potassium iodide in the pres- ence of hydrochloric acid. Subdivision of Albumoses. — The different albumoses formed in the earlier stages of the decomposition may be grouped under protoalbumoses and hetei'oalbumoses, which collectively form the pnmary albumoses. From each group of primary albumoses further hydrolysis, as in the process of peptic digestion, forms deuteroalbumoses, and finally peptones. This is shown in the scheme of Neumeister, representing the action of pepsin and hydrochloric acid,* without reference to the hemi- and anti-groups of the molecule given on the next page. * Lehrhuch Physiol. Chem., p. 231 ; cf. p. 180. 156 FLESH FOODS. Diagram op the Action op Pepsin on Proteids. Native Proteid. Syntonin. Protoalbumose. Heteroalbumose (Dysalbumose). 1 1 Deuteroalbumose. Deuteroalbumose. 1 I Peptone. Peptone. Primary Alhumoses. — These are precipitated, though not com- pletely, by neutralising the solution, and saturating it with sodium chloride, which gives a white precipitate, dissolving on heating, and reappearing on cooling. They are also precipitated by nitric acid, while deuteroalbumoses give no precipitate mitil the liquid has been first saturated with common salt. Other precipitants for primary albumoses are potassium forrocyanide with acetic acid, and copper sulphate, though these also sometimes precipitate small quantities of deutero- albumose. Protoalbumoses are soluble in distilled water, and in dilute solutions of salt, and are partially precipitated by saturating an acidified solution with salt. They are also precipitated by mer- curic chloride and by copper sulphate. Heteroalbumosea are insoluble in distilled water, but dissolve in weak solutions of salt. They are precipitated like the globulins by pouring their neutralised solution into a large volume of pure Avater, or by saturating the solution with sodium chloride. They are also precipitated by copper sulphate and by mercuric chloride (in acid solutions). Dysalbumose. — By being left for a long time in contact with water, or by drying, heteroalbumoses are converted into a peculiar insoluble modification known as dysalbumose, which can be j^rti- ally reconverted into heteroalbumoses by treatment with dilute acid or sodium hydroxide. Deuteroallnimoses are much more closely allied to the peptones than are primary albumoses. They are soluble in water and solutions of salts, and are not precipitated by saturating their solution with sodium chloride. Nitric acid precipitates them only in the presence of an excess of salt, and the precipitates do not dissolve so readily on heating as those of the primary albumoses. schkotter’s albumose. 157 Chittenden* gives the following method the nrimary compounds in the absence of peptones. The somtio ^ neuSd and saturated t,itl. sodinm nrecinitates the primary albumoses. On adding acetic acid, d op nC to the mtrate. the residual protoalbumoses are precip. tated too-ether with a small amount of deuteroalbumose. From the filtrate from this precipitate the .^o^teroalbumoses Jin be obtained in a pure condition by dialysing out the salt and jicl concentrating the liquid, and precipitating the proteid with not an easy matter to completely precipitate the whole of the deuteroalbumoses in a solution of mixed albumoses, and Kuhne states that long-continued boiling in the alternately neutral and alkaline saturated liquid is necessary. „ , f S Friinkel t proposes to separate deuteroalbumoses by means ot cupric sulphate, and thus to avoid the difficulty of removing laree quantities of salts by dialysis. According to Neumeister this reagent gives a voluminous precipitate, ^ solution ot 1:500, and a turbidity with a solution of 1:1000 of deutero- albumose containing protoalbumose, but gives no sign of Jr- bidity with pure deuteroalbumose. On adding a dilute soffition of cupric sulphate to the albumose solution, a tough coherent precipitate is formed, while any turbidity left in the solution generally disappears after a few hours. The copper is removed from the solution by adding a hot saturated solution of barium ferrocyanide, until a few drops of the liquid on filtration show only a trace of copper. At this stage the liquid is acidified with acetic acid, warmed, filtered, and the filter washed. Barium ferro- cyanide solution is added, drop by drop, to the filtrate so long as a red precipitate is formed, then barium acetate to remove the sulphuric acid. Finally the solution is concentrated and poured into strong alcohol, and the deuteroalbumose dehydrated with absolute alcohol, and washed with ether. Schrotter’s Albumose— R. Schrotter J isolated from Wittes peptone an albumose, or group of albumoses, in the following manner: — The soluble impurities were extracted with methyl alcohol, and the residue dissolved in water acidulated with sulphuric acid, and treated with zinc dust and sulphuric acid. After several days the liquid was warmed on the water- bath, and, after the removal of the sulphuric acid, filtered, con- centrated, and evaporated in vacuo over sulphuric acid. The residue was exhausted with hot methyl alcohol, the extract con- centrated, and the albumose precipitated with absolute ether. * Medical Record, 1894, p. 485. t Monatsheft. f. Chem., 1897, p. 433. J Ibid., xiv. p. 612. 158 FLESH FOODS. Its composition, making allowance for the ash (0-2 to 0‘5 per cent.), was:— Carbon, 50'5 to 51-3; hydrogen, 6-4 to 7-Q • nitrogen, 16-5 to 17-1 ; and sulphur, M per cent. ' Its molecular weight determined in an aqueous solution by Raoult’s method varied from 587 to 714. ^ For the composition of various albumoses and other proteoses prepared by Kiihne, Chittenden, and their co-workers, see page 181. _ Schrotter * controverts the generally accepted views as to the formation of albmnoses as an intermediate stage in the production of peptones by enzymes. In his opinion both albumoses and peptones are precipitated by saturation with ammonium sulphate, but the former may be readily distinguished by their higher molecular weight, larger percentage of nftrogen, and by the fact that they contain sulphur, which peptones do not. This view of Schrotter s illustrates the general want of agree- ment as to the nature of peptones, different chemists attaching that name to some certain group of the hydrolysed proteids, which they regard as more worthy of it than some other. It seems, however, most fitting to reserve the name for the most soluble of the derivatives, which are precipitated by strong alcohol, and are not removed by saturation with zinc or ammonium sulphate, although, even in the latter case, lower deuteroalbumoses may be grouped with the peptones. Composition of Peptones.— The analyses by Chittenden f of peptones from different sources, given on p. 159, do not bear out Schrotter’s theory that peptones differ from albumoses in not containing sulphur. General Properties of Peptones. — Peptones are much more soluble than albumoses, or at least the higher albumoses (proto- albumoses), and require the addition of much alcohol to pre- cipitate them from their solution. They are not coagulated by heat, and possess great diffusibility. They cannot be salted out by an addition of zinc or ammonium sulphate, a property which is usually regarded as the distinguishing feature between albumoses and peptones. In the pure state a peptone is a hygroscopic amorphous powder, with a bitter taste. It rapidly absorbs moisture from the air and becomes resinous. In the anhydrous condition it dissolves in water with a hissing noise, and the evolution of a considerable amount of heat. % * Monatsheft. f. Chem., xiv. p. 612, and xvi. p. 609. + Medical Record, 1894, pp. 486 and 646. HEMI- AND ANTI-PEPTONES. 159 Chemical Composition op Representative Peptones. Peptone. Carbon. Hydrogen. Nitrogen. Sulphur. Oxygen. Amphopeptone from ) Blood Fibrin, . \ 48-75 7-21 16-26 0-77 27*01 Hemipeptone from 1 Coagulated Egg > 49-38 6-81 15-07 1*10 27*64 Albumin, . . ) Peptone from Hemp 49-40 6-77 18*40 0*49 24-94 Seed, . Antipeptone from 6-51 16-30 0-68 26-57 49*94 Casein, . . |i Antipeptone from 1 6-87 16-62 1-16 26-09 46-26 Myosin, . . ■ i Many of the ordinary proteid precipitating reagents are not avaUable for peptones. Thus, they are not precipitated hy nitric acid with or without the addition of salt, by acetic acid with potassium ferrocyanide, or by an excess of picric acid. On the other hand, they are precipitated by chlorine or bromine, by tannin from a neutral solution, by phosphotungstic or phospho- molybdic acid, by uranium acetate, by mercuric chloride, and by absolute alcohol (c/. pages 164-176). ... , In the biuret reaction they resemble albumoses in giving purple colorations without warming, whilst albuminous substances give more of a violet colour which only becomes purple on applying Peptones can combine with either acids or alkalies to form salt-like compounds, and appear to form definite compounds with hydrochloric acid. Hemijpeptones and Antipeptones. — Of the peptones produced by the hydrolysis of albuminous substances or proteoses, part are capable of being further broken up by trypsin, with the formation of simpler substances, such as tyrosine or leucine. The hemi- group of the original molecule appears to contribute chiefly to these, and they were therefore termed hemipeptones by Kiihne and Chittenden. For a similar reason the other portion of the peptones, which resist the action of the enzyme, received the name of antipeptones. Both kinds are grouped together under the name of amphopeptones. Gelatin Peptones. — Under the influence of dilute acids, of digestive, and of bacterial enzymes, or of the continued action of 160 FLESH FOODS. boiling water, gelatin is converted into a much more soluble substance or substances knowm as gelatin peptone. The gelatin undergoes a change analogous to that which occurs in the digestion of simple albuminous substances, and the resulting product, or series of products, is no longer capable of gelatinising. No method of separating these decomposition products of gelatin from ordinary peptones has yet been devised, although Salkowski has described a number of colour reactions which are said to distinguish the two classes of derivatives from one another (c/. page 162). Reactions and Physical Properties of Proteids. The Combination of Proteids with Hydrochloric Acid. — It is well known that in artificial digestion experiments the free hydro- chloric acid gradually disappears, and that a further addition of it is required to carry on the process. Cohnheim * has prepared albumoses and peptones according to Kiihne and Cliittenden’s directions, and has determined the average amount of hydrochloric acid with which each kind can combine at a definite temperature. At 40° C. he found that protoalbumoses (in 2 '5 per cent, solu- tion) combined with 4'32 per cent, of their weight of hydrocliloric acid, deuteroalbumoses with 5 '48 per cent., heteroalbumoses with 8'16 per cent., and antipeptones with 15'87 per cent, in the mean. On varying the conditions of temperature and concentration there was a difference in the amounts of hydrochloric acid added, but there was invariably a constant relation in this respect between the three albumoses and the peptone employed. The amount of hydrochloric acid absorbed can be determined by treating the albumose with a definite quantity of the acid in excess, salting out the compound with ammonium sulphate, and determining the residual acid in the filtrate. But this method is said not to be applicable in the case of deuteroalbumoses and antipeptones. It is noticeable that the order in which these compounds can be arranged as regards hydrochloric acid absorption is not the same as the arrangement according to diffusibility, solubility, etc. Cohnheim suggests that probably albumoses can combine with hydrochloric acid in more ways than one, or, in other words, be di-basic. Colour Reactions of Proteids. — There are numerous colour tests for proteid substances, but as many organic bodies, especially * ZcU. Biol., 1896, p. 489. COLOUR REACTIONS OF PROTEIDS. 161 among the aromatic compounds, give similar colorations with the same reagents, they cannot be regarded as absolutely characteristic. The Biuret Reaction. — On adding an alkali to the solution of a proteid, and then, drop by drop, a weak solution (2 per cent.) of copper sulphate, there is no precipitation of copper hydroxide, but the liquid becomes violet. Care must be taken to avoid an excess of copper salt, or the violet colour will be masked by the blue. The name of the reaction is derived from the fact that biuret or allophanamide [(CO)2(NH2)2.NH] gives a similar purple or red colour under the same conditions. It is doubtful, however, whether the colour is produced by the same group in the molecules of biuret and of albuminous substances. If a nickel salt be used instead of copper sxilphate, the colora- tion will be yellow or orange. According to Neumeister the reaction will detect one part of a proteid in 10,000 of water, while Hoffmeister gives the limit of sensibility as 1 in 12,000. F. Klug * has based a quantitative method of estimating proteids on the spectroscopic examination of the liquid in the biuret test. Milton’s Reaction. — On boiling proteids with a solution of mercuric nitrate containing a little nitric acid, a red coloration or precipitate is obtained. This reaction is also given by aromatic compounds, such as tyrosine, in which only one atom of the benzene group is replaced by hydroxyl : — Ptt/OH ^6^4\cH2.CH(NH2).COOH. The reaction is much less pronounced with proteids than with tyrosine, but is probably due to the same group in the molecule. Xanthoproteic Reaction. — On heating proteids with strong nitric acid, a yellow precipitate or colour is obtained from the formation of nitro derivatives. This becomes deep orange on the addition of ammonia in excess. The reaction is also given by many aromatic compounds. Adamkiewicz’s Reaction. — When albumin, in as dry a state as possible, is dissolved in glacial acetic acid, and half its volume of concentrated sulphuric acid added to the solution, a violet-red colour is produced either immediately or after boiling for some time. Liebermann’s Reactum. — When certain proteid substances are washed with alcohol and cold ether, and heated with concentrated hydrochloric acid (1T9 sp. gr.), they give a violet coloration. Rimini f has shown that this is due to the presence of traces of vinyl alcohol in the ether. * Chem. Centralblatt, 1893, ii. p. 499. t Gazz. Chim. Ital., 1899, p. 390. L 162 FLESH FOODS. Colour Reactions of Albumin and Gelatin Peptones. — Salkowski gives the following table of the colour reactions of albiunin and gelatin in solution : — Albumin Peptone. Gelatin. Gelatin Peptone. 1 C.C. of Solution -1- (5 c.c. Acetic Acid -f- 5 c.c. Sulphuric Acid), . . Violet. Yellowish. Yellowish. Equal volumes of the Solution -1- concentrated Sulphuric Acid, . . Dark brown. Yellow. Yellow. Millon’s reagent, . . . Keddisb. Colourless. Colourless. 5 c.c. of Solution-! 1 c.c. of Nitric Acid (sp. gr. 1’2) — boil and add so- dium hydroxide, . . Dark orange. Lemon-yellow. Lemon-yellow. Heat Coagulation of Proteids.— As many of the simple albuminous bodies coagulate at a different temperature, it is often possible to separate them by means of fractional coagulation. For this purpose Halliburton has devised the apparatus shown below. Fio. 18a.— Halliburton’s apparatus. T, tap for water ; C, copper vessel with spiral tube ; d and 5, inlet and outlet tubes ; test-tube with fluid and thermometer. The test-tube containing the solution of the proteids is kept in water at the given temperature for five minutes, while the degree of acidity is kept constant by the addition of dilute (2 per cent) acetic acid, added from a burette, the right proportion to be HEAT COAGULATION OF PEOTEIDS IN FLESH, 163 added after neutrality being about 1 drop to each 3 c.c. of the liquid. Thus, for example, from human blood serum there can be separated in this way fibrinogen, coagulating at 66° C. ; serum globulin at 75° C. ; and three kinds of serum albumin at 73° C., 77° C., and 85° C. respectively. Of other important proteids, egg albumin coagulates at 72° to 73° C., myosin at 56° C., vitellin at 75° C., and haemocyanin at 65° C. J. H. Milroy * has studied the degree of coagulation which the albuminous substances of flesh imdergo when heated at different temperatures. In each experiment the finely-divided flesh was lieated in a beaker for an hour at temperatures ranging from 50° to 120° C., and the non-coagulated albuminous matter ex- tracted with a solution of ammonium chloride (15 per cent.). On extracting different kinds of flesh, without previous heating with this solution, the following amounts of proteids, calculated on 100 parts of the dry flesh, were extracted : — Fresh beef, 14‘0 to 23'5; ham, 9'31 j salt beef, 13'66 ; beef pickled in acetic acid, 5 '87 ; calf’s brain, 2 ’77. The difference between the coagulable albumin extracted from the non-heated flesh and from the same flesh heated at different temperatures gave the amoimt coagulated by the heat. PROPOKTION OF ALBUMINOUS SUBSTANCES COAGULATED BY HEAT. Temperature. -c. Fresh Beef. Ham. Salt Beef. Beef pickled in Acetic Acid. Calfs Brain. 50 45-95 to 55-10 45-87 63-55 67-13 51-99 60 64-37 „ 74-47 54-25 84-04 88-44 80-15 70 90-66 „ 91-01 95-28 95-32 100-0 84-12 80 99-11 „ 100-0 99-18 100-00 100-0 90-26 90 to 120 100-0 100 100-00 100-0 100-0 In one experiment the fresh unheated flesh yielded to the ammonium chloride solution 22'77 per cent, of coagulable albu- minous matters. On slightly roasting the same flesh the amount extracted from the interior was 13 "08 and from the exterior 4 ’71 to 5 '21 per cent., while the quantities obtained from the interior and exterior, after strongly roasting the meat, were 0T3 and OTl per cent, respectively. Optical Rotation of Proteids. — All proteids rotate the beam * Archiv Hyg,, 1895, xxv. p. 154. 164 FLESH FOODS. of polarised light to the left. The specific rotatory powers of representatives of various groups are as follows : — Egg Albumin, Serum Albumin, . Syntonin from Egg Albumin, Sodium Albuminate, Protoalbumoses, (various sources) Deuteroalbumose, . Heteroalbumose, . Fibrinogen, . [a]D. Authority. -33-5“ Hoppe-Seyler. -56 -63-12 Haas. -55° 99 -71-40° to -79-05 Kiihne and Chittenden. -79-11 9 9 9 9 -68-65 9 9 99 -43 Hermann. Hoppe-Seyler t has devised a polarimetrical method of quanti- tatively estimating proteids, based on the difference in their rotatory power. The Precipitation of Proteids by Various Keagents. Precipitation of Proteids with Alcohol. — All proteids are insoluble in alcohol, and can be precipitated from their aqueous solutions by adding it in sufficient quantity. When albuminous bodies are precipitated by dilute alcohol they are apparently unaltered, but when the alcohol is concentrated and its action continued for some time, coagulation takes place, and the pre- cipitate will not subsequently dissolve in water. Alcoholic precipitation is often used as a means of separating the proteid constituents of meat extracts (c/. p. 199). All such methods appear to depend on the fact that the further the hydrolysis of a given proteid has proceeded the more soluble become its products, and the greater the amount of alcohol required for their precipitation. Hence by varying the strengths of alcohol the proteid nitrogen might be subdivided in many different ways. Precipitation of Proteids by Saturation of their Solutions with Salts. — It is often possible to effect a more or less complete separation of a proteid or group of proteids from its solution by saturating the liquid with a readily soluble salt, and this has been largely used in the quantitative analysis of proteid substances. In such cases the precipitation is probably brought about merely by a withdrawal of the water required for the solution of the proteid, and is not due to the formation of a definite compound between the metallic salt and the proteid, as in the precipitations in Schjeming’s method of analysis. The characteristics of the proteids thus ‘ salted out ’ remain unchanged. Certain proteids, such as peptones and some deuteroalbumoses, are soluble in con- centrated solutions of ammonium or zinc sulphate. • Zdt. Biol, XX. p. 11. t Virchow's Archiv, xi. p. 547. THE ‘SALTING OUT’ OF PKOTEIDS. 165 Saturation with Ammonium Sulphate. — For years this was the method generally employed for the separation of albumoses. _ The liquid was boiled and filtered to remove coagulable albuminous substances, and an excess of ammonium sulphate added to the filtrate when cold. The precipitate was collected, washed with a saturated solution of ammonium sulphate, boiled in water with barium carbonate to expel the ammoniacal nitrogen, and the residual nitrogen estimated by Kjeldahl s method. Saturation with Zinc Sulphate. — Precipitation with ammonium sulphate suffers from the great drawback of the introduction of nitrogen during the precipitation, and the necessity of removing this before the proteid nitrogen of the precipitate can be estimated. To avoid this, Bbmer made experiments with zinc sulphate as a precipitant, and found that it precipitated practically the same amount of proteid nitrogen. Subsequently, in conjunction wdth Baumann,* he made parallel experiments on the two methods of saturation to determine to what extent nitrogenous bases, amide bodies, and ammonia were precipitated in each case. The results showed that ammonium sulphate precipitates considerable quanti- ties of tyrosine and leucine. With zinc sulphate, on the other hand, ammonium salts, asparagine, leucine, tyrosine, and kreatine, in the degree of concentration in which they occur in meat extracts, are not precipitated, or, at most, the amount of the precipitate is so small as to be negligible. The precipitation is most complete after the addition of dilute sulphuric acid (1 : 4) in the proportion of 1 part to 50. Maynedum Sulphate. — In Schjerning’s opinion it is probable that all readily soluble sulphates would precipitate all albumins and albumoses if added to saturation in the presence of a little acetic acid. In his method of analysing proteid substances, magnesium sulphate is used in place of zinc or ammonium sul- phates as the saturating agent (c/. p. 173). Saturation with Sodium Chloride. — By means of this salt albumoses can be subdivided into two groups — primary proteoses, which are precipitated on saturating their neutral aqueous solution with sodium chloride, and secondary proteoses, which are only partially precipitated on the addition of nitric acid to the pre- viously saturated solution (see pp. 166-157). The Precipitation of Proteids by Metals in Relation to the Periodic Law. — Schjeming f has recently shown that salts of analogous metals precipitate practically the same amount of nitrogen from solutions of mixed proteids, whereas the metals of non-analogous series show a marked difference in this respect. * Zeit. Unters. Nahr. Oenussm., 1898, p. 106. t Zeit. anal. Uhem,, 1898, p. 73. 166 FLESH FOODS. Parallel determinations were made on the lines of his general method (p. 171), with solutions of diastase, peptone, egg albumin, milk, and beer, and the following were the mean results obtained throughout the series : — Nitrogen per cent, precipitated by Chlorides. Acetates. Sulphates. CO s_/ Lead. . C o . c « O '’Ss- Mag- nesium. Zinc. Cadmium. Nickel. Iron. (FeO) Man- ganese. (MnO) Sodium. 5-1 6-4 63-0 60-8 4-8 40-0 38-2 35-5 37-5 44-3 43-4 The results obtained with chromium acetate were much too low, but Schjeming accounts for this on the ground that the complete analogy between chromium and iron is doubtful Although copper salts have some analogies with salts of the magnesium group, precipitation with copper sulphate gave very much lower results, either with or without saturation. For example : — Magnesium. Copper. Iron. Beer, . Egg Albumin, 17-4 94-8 4-6 81-3 82-8 From this it is evident that the sulphates of copper and iron precipitate almost the same amounts of proteid nitrogen. With the acetates of lead, copper, and mercury, which form a naturally ascending but not analogous series of metals, the follow- ing percentages of nitrogen were precipitated ; — Lead Acetate. Copper Acetate. Mercuric Acetate. Cold. Boiling. Cold. Boiling. Beer, W ort. 160 20-8 19- 9 20- 8 25-4 24-3 40-1 47-0 43-6 46-3 With regard to the influence of the acid, it was found that for 167 THE PRECIPITATION OF PROTEIDS. the same metal the acetate Precipitates more nitrogen to the sulphate, and the sulphate more than the chloride. With , ^ latter, the largest precipitation took place in the cold solution , with the other salts, on boiling. . ^ j The acetates of calcium and strontium precipitated respectively 84-4 and 8o’4 per cent, of the nitrogen of egg albumin. Generally speaking, the precipitating power of metals appeared to increase with their atomic weight in the analogous series. _ The salts of noble metals are unsuitable as precipitants, cnieny on account of the readiness with which they are reduced to the metallic state. , Schjeming gives the following summary with regard to tne suitability of metallic salts as precipitating agents. _ 1. The sulphates and chlorides precipitate at most true albumin, and that often incompletely. , n a a 2 The acetates of the magnesium group, and of the extended magnesium group, precipitate only true a,lbumins. The precipi- tating power appears to rise with the atomic weight. ^ 3. The acetate of lead and its analogues (?) precipitate all pro- teids up to the albumoses. j 4. The acetates of the analogous oxides FogOg and Mn^Ug pre- cipitate all proteids up to the real peptones. 5. Uranium acetate and phosphotungstic acid precipitate all proteids, being examples of analogous metals, though of different Lilts. Uranium acetate can also precipitate some of the ammoniacal nitrogen in the presence of phosphoric acid, whilst phosphotungstic acid precipitates the whole of it. 6. Mercuric chloride precipitates all the proteids up to the albumoses, or the same amount of nitrogen as lead acetate. Mer- curic acetate precipitates all the proteids, and, in addition, more or less of the amide nitrogen. _ Precipitation of Proteids with Phosphotungstic Acid. This reagent is widely employed as a general precipitant for all proteid substances, but the separation is not sharp, and the further the hydrolysis of an albuminous substance has been carried, the less complete is the precipitation. Peptones are only incompletely precipitated, while, on the other hand, certain flesh bases, such as kreatine and kreatinine, are completely precipitated. Mallett * classifies the proteid and amide bodies of commonly occurring food substances into three groups as regards their be- haviour with phosphotungstic acid. 1. Those which, even in fairly strong solution, give no precipi- tate, e.g., leucine, asparagine, aspartic acid, and tyrosine. 2. Those which are precipitated in strong solutions, the pre- * Abst. Analyst, 1898, p. 329. 168 FLESH FOODS. cipitate dissolving on heating and reappearing on cooling, e.g., glutamine, kreatine, kreatinine, hypoxanthine, camine, and urea*. Peptone precipitates coagulate, and partially dissolve on heating. 3. Those which are precipitated, the precipitate not being sensibly dissolved on heating, e.g., egg albumin, fibrin, casein, legumin, globulin, vitellin, myosin, syntonin, haemoglobin, albu- mose, gelatin, and chondrin. The precipitates given by certain amide bodies are soluble in hot water to the following extent : — Betaine, 1 in 71 parts at 98-2° C. ; kreatine, 1 in 107 parts at 98T° C.; kreatinine, 1 in 222 at 97-9“ C. ; hypoxanthine, 1 : 98 at 97'6° C. : and camine, 1 in 132 at 98-4° C. Methods of Prepanugand Using the Reagent. — (1.) From 5 to 10 grammes of phosphotungstic acid are dissolved in 100 c.c. of 2'5 per cent, hydrochloric acid (Mallet). (2.) 120 grammes of sodium phosphate and 200 grammes of sodium tungstate are dissolved in water and the solution made up to a litre. The solution of proteid substance is mixed with dilute sulphuric acid (1:1) and the above solution in equal quantities at a temperature of from 60° to 65° C. After standing for twenty-four hours, the precipitate is collected, washed with sulphuric acid (1 : 2), and the nitrogen it contains estimated by Kjeldahl’s method. Pr^ipitation of Proteids by Halogens. — Chlorine Precipitation. — Proteids combine with the halogens, forming insoluble sub- stances. Although this fact was pointed out years ago by Mulder, it had been lost sight of until Rideal and Stewart* described a method of estimating proteids by precipitating them from their solutions with chlorine. In their method, a current of chlorine is passed through the solution, which should contain not more than 0’2 per cent, of proteids, until the precipitate becomes granular and frothing ceases. After standing, preferably for some hours, the liquid is filtered through a hardened Schleicher and Schiill’s filter paper, which has been previously weighed. The precipitate is washed witli cold water, dried as far as possible in warm air, and finally, ill vacuo, over sulphuric acid. The weight of the chlorine pre- cipitate, multiplied by 0-78, gives the amount of proteid present. In the test experiments described in the original paper, a deter- mination of the nitrogen in the dried precipitate, and multiplica- tion of the results by 5‘5 in the case of gelatin, and by 6 '33 in the case of the other proteids examined, gave satisfactory results in most instances. It was found that meat bases, such as kreatinine, were not pre- cipitated by chlorine. * Analyst, 1897, pp. 228-235. PBECIPITATION OF PEOTEIDS BY HALOGENS. Ib9 Bromine Precipitation. — Some experiments were also made by Rideal and Stewart with bromine as the precipitant, and A. H. Allen * suggested the determination of nitrogen in the precipitate without previous drying. The following simplified method was subsequently worked out by Allen and Searle t on these lines : — The solution containing about 1 gramme of the proteid is diluted to 100 c.c., and rendered distinctly acid by the addition of dilute hydrochloric acid. A considerable excess of bromine water is then added, and the liquid stirred for some time. The precipitate is allowed to settle, the supernatant liquid decanted through an asbestos filter, the precipitate washed with cold water, and if necessary with bromine water, or sodium sul- phate solution, and the nitrogen it contains determined by Kjeldahl’s method, and calculated into proteid by the factor 6 '33 (or 5 ‘5 for gelatin). Solutions of kreatinine, asparagine, and aspartic acid gave no precipitate with bromine under these conditions, and the precipitate given by ‘ meat extractives ’ extracted from fresh beef with water contained only a very inconsiderable amount of nitrogen. Some of the principal results thus obtained were — Substance. Nitrogen per cent. Nitrogen Multiplied by Factor. Total in Original Sub- stance. Precipitated by Bromine. Total in Original Sub- stance. Precipitated by Bromine. Factor Em- ployed. Commercial Gelatin, 14-10 14-00 77-5 77-0 Jelatin Peptone, . 14-10 13-90 77-5 76-5 Commercial Scale Albu- min^ .... 8-80 8-72 55-8 55-2 1 iyntonin from Scale Al- bumin, 9-86 9-60—9-76 62-41 60-77— 61-78 Cigested Scale Albumin, 8-89 8-81 56-3 55-8 fresh White of Egg, 1-89 1-88 11-96 11-90 L a iyntonin from White of Egg 1 89 1-89 11-96 11-96 ’eptone from White of Egg 0-70 0-69 4-43 4-37 Jeef Extractives, . 0-33 0-004 2-11 0-03 There can be no question as to the value of halogen precipita- tion, since it has been shown, both by Rideal and by Allen, that * Analyst, 1897, p. 233. t 1897, p. 259. 170 FLESH FOODS. meat bases are not precipitated (or if so the precipitates are soluble in dilute acid). Thus we have a means of exactly separating them from albuminous and gelatinous compounds, which has long been a want in the analysis of meat extracts and similar preparations. Notes on Schjerning’s Eeagents. — Uranium Acetate. — Kowa- lewsky * showed that proteids were precipitated by uranium ace- tate, but that the precipitates were somewhat soluble in water. Albumins and globulins, and, according to Schjerning, albumoses and peptones, but not amido-compounds, such as asparagine and leucine, are precipitated. The precipitation may be made at the ordinary temperature, but must always be from a neutral or slightly acid solution (see also pp. 173 and 205). The chief pre- caution is to have the uranium solution quite clear and free from basic compounds. Schjerning states that if phosphoric acid be present in the solution in a larger proportion than the proteid, the ammoniacal nitrogen, and possibly a very little of the amide nitro- gen present, are precipitated. Tin CMoride was first proposed as a reagent for proteid preci- pitation by Drechsel t and by Siegfried.! It precipitates about 90 per cent, of the albuminous substances in white of egg, and in Schjeming’s method of analysis (p. 171) all proteids precipitated by it are termed albumin I. Lead Acetate. — Berzelius J was the first to point out that albu- min is quantitatively precipitated by basic lead acetate, hut^ only partially by the normal salt. According to Schjerning it precipitates albumins, and proteid compounds not far removed from nucleins (denucleins). Ferric Acetate § was proposed by Schmidt-Mulheim for the pre- cipitation of albuminous substances and pro-peptones (proteoses). Schjerning found that it precipitated albumins, albumoses, and ‘ denuclSins.’ Stutzer’s Copper Hydroxide Reagent.— This is prepared by dissolving 100 grammes of copper sulphate in 5 litres of water, adding 2 ‘5 grammes of glycerin, then a dilute solution of sodium hydroxide until the reaction is alkaline, and filtering. The pre- cipitate is thoroughly mixed with water containing 5 grammes of glycerin per litre, and decanted and filtered, until all alkali has been removed. The residue is triturated with a litre of water containing 10 per cent, of glycerin, until a mud is obtained which can be dra^sm up into a pipette. It is kept m a well-closed llask in the dark. * Zeit. anal. Cliem., xxiv. p. 551. t BerichU. xxiii. p. 3096 and xxiv. p. 418. t Lehrhuch der Cherti., ix. p. 43. § Zeit. anal. Chem., xix. p. 127. ANALYSIS OF PEOTEID SOLUTIONS. i / L This was said to precipitate albumoses, but not peptones or gelatin. But Rideal and Stewart * have shown that a considerable proportion of gelatin is precipitated, and that this is probably not due to any hydrolysis of the latter in the course of manufacture. They consider that the reagent cannot be relied upon to ettect a separation of albumoses from gelatin, and this is borne out by their results, in which the amount of nitrogen precipitated by Stutzer’s reagent is only about half that contained in the albu- mctees obtained by saturating the solution with ammonium sul- phate. Nelson’s No. 1 Gelatin. Coignet’s Extra Gelatin. Swiss Gold Leaf Gelatin. Somatose. Witte’s Peptone. Total Nitrogen. 13-8 14-61 14-33 13-72 14-67 Nitrogen in Ammonium 13-92 12-44 10-13 Sulphate Precipitate, Nitrogen in Stutzer’s Precipitate, 13-69 13-63 4-59 6-64 4-52 4-09 5-91 Schjerning’s Method of Analysing Proteid Solutions.— From the fact that metals of analogous series precipitated the same amount of nitrogen from solutions of different proteids, while the nitrogen precipitated by metals of non-analogous series is dis- similar, Schjerning came to the conclusion that the precipitates are compounds of the respective metals with definite proteids. To these proteid substances he has given the following provi- sional names, as indicating to some extent their character. From comparison with the results obtained with malt extract he considers that there are two kinds of albumin in milk. Precipitated by, Tin chloride =a Contains the Proteids. Albumin I. Lead acetate ) ( Albumin I. Mercuric ^ =6 -j Albumin II, chloride ) Denuclein. Precipitated by. Uranium acetate Contains the Proteids. f Albumin I. I Albumin II. =d ■: Denuclein. I Albumose. ^ Peptone. Ferric acetate =c /Albumin I. J Albumin II. j Denuclein. \ Albumose. ( Albumin I. Magnesium sulphate -! Albumin II. 1^ Albumose. * Analyst, 1897, xxii. p. 230. 172 FLESH FOODS. From these five precipitations, the amo\mt of the different proteids or groups of proteids can be calculated, since Albumins I. M II Denucleins Albumoses Peptones The reagents required are : — 1. A solution of tin chloride, prepared by dissolving 50 grammes of tin in a weighed flask containing a sufficient quantity of boiling concentrated hydrochloric acid, and a little platinic chloride. The solution is evaporated down to about 130 grammes, made up to a litre and filtered. 2. A solution of normal lead acetate, containing about 10 per cent, of the salt, and 10 to 12 drops of 45 per cent, acetic acid per litre. 3. A 5 per cent, solution of mercuric chloride. 4. Pure dry ferric acetate. 5. Dilute acetic acid, containing 15 c.c. of 45 per cent, acid in a litre. 6. A solution of pure uranium acetate (about 10 per cent.) free from ammonia. 7. Pure crystallised magnesium sulphate. 8. A solution of ordinary sodium phosphate, containing about 0'4 per cent, of the crystallised salt. 9. Calcium chloride solution (about 10 per cent.). The solution containing the proteids is first diluted, so that 10 c.c. contain a quantity of total nitrogen corresponding to about 5 c.c. of decinormal acid. In some cases, when the solution con- tains little or no ash, the addition of mineral matter (solutions 8 and 9) is necessary. This point may be determined by a pre- liminary test ; — If the number of c.c. of the proteid solution which correspond to about 10 c.c. of decinormal acid do not, on boiling, completely precipitate the iron from a solution of 0'8 gramme of ferric acetate dissolved in 40 c.c. of dilute acetic acid (reagent 5), and 50 to 100 c.c. of water, the precipitations with tin, lead, and iron must be preceded by the addition of reagents 8 or 9. The Tin Chloride Precipitation. — About 5 c.c. of the tin chloride solution (reagent 1) are added to 25 c.c. of the proteid solution. After stirring well, the beaker is covered with a glass, and left for from 6 to 24 hours. The precipitate is then collected on a filter and washed with cold water. If the proteid solution be poor in ash, 10 c.c. of calcium chloride solution (reagent 9) are added Precipitate a 6-[a-{-(c-e)] c-e c-h d-c schjerning’s method of analysis. 173 before the tin chloride, and the precipitate washed with a cold 1 per cent, solution of calcium chloride. Tlie Lead Precipitation. — To 25 c.c. of the proteid solution is added a sufficient amount of lead acetate solution (reagent 2), the amount varying with different substances. Care must be taken to avoid an excess of the reagent, or part of the precipitate may be redissolved. After adding the reagent, the liquid is boiled, and the precipitate collected and washed with cold water. If the proteid solution contains little ash, sodium phosphate solution (No. 8) is added before boiling, in the proportion of about three volum4 to each volume of lead acetate solution used. Since the lead precipitate is somewhat soluble in the precipitating reagent, a correction is necessary. This Schjerning has found experimen- tally to be about 0T5 c.c. of decinormal acid for each 100 c.c. of filtrate and washings. The Mercuric Chloride Precipitation. — Five c.c. of the mercuric chloride solution (No. 3) are added to 25 c.c. of the proteid solution, the liquid allowed to stand for 4 to 24 hours at the ordinary temperature, the precipitate filtered off, and washed with a cold 0-5 per cent, solution of mercuric chloride, and the nitrogen it contains estimated by Kjeldahl’s method. The amounts of pro- teids precipitated by lead acetate and by mercuric chloride are identical, but as the latter usually gives more satisfactory results, the lead precipitation need only be used in exceptional oases. The Iron Precipitation. — Ferric acetate (O' 8 gramme) is dis- solved in 40 c.c. of dilute acetic acid (reagent 5) and 50 to 100 c.c. of water, the solution being heated to the boiling point. 20 c.c. of the proteid solution are then added, and the liquid again heated to boiling. The precipitate is filtered off and washed three or four times with boiling water. The filtrate should be quite clear, and if this is not the case, from 15 to 25 c.c. of the sodium phosphate solution (No. 8) should be added immediately after the second boil- ing, the liquid being meanwhile stirred and kept boiling. With practice the right amount of phosphate can be estimated. Twenty c.c. have no injurious effect if these directions be followed, and only in exceptional cases is it necessary to add greater quantities (at most 25 c.c.). The Uranium Precipitation. — To 25 c.c. of the proteid solution are added 20 to 25 c.c. of reagent 6, the liquid heated to the boil- ing point with constant stirring, and allowed to stand over night in a dark place. The precipitate is then collected on a filter, and washed with a cold 1 to 2 per cent, solution of uranium acetate. The correction for the solubility of the precipitate corresponds to O'lO c.c. of decinormal acid for each 100 c.c. of filtrate and washings. 174 FLESH FOODS. The Magnesium Sulphate Precipitation. — Five or six drops of 45 per cent, acetic acid are added to 20 c.c. of the proteid solution, and the beaker placed in a water-bath kept at 33° to 36° C. From 18 to 20 grammes of finely powdered magnesium sulphate (MgS04-h7H20) are added, with constant stirring, and the liquid allowed to stand for thirty minutes to an hour at the ordinary temperature, a stir being given from time to time. The precipitate is then filtered off, and washed with a cold saturated solution of magnesium sulphate containing 4 to 5 grammes of 45 per cent, acetic acid per litre. Some of Schjeming’s results of the analysis of solutions of different proteids are shown in the subjoined table, which is com- piled from others given in his various papers on the subject. A minus sign indicates an error in the calcxdated results, and where it occurs there was none of the given proteid present. Egg Albumin. Serum of Calf s Blood. Witte’s Peptone. 'Liebig’s Flesh Peptone. Liebig’s Meat Extract. 1. 1. 1. 2. 1. 2. Albumin I., 89-2 85-0 83-4 2-7 30 13-6 13’9 10-7 II., 1-9 2-2 120 18-8 2-6 0-0 Denuclein, . 1-2 1-6 2-9 8-0 12-2 8-5 9-2 10-2 Albumose, . 3-9 50 0-3 48-5* 25-4 32 1 33-2* 6-1 Peptone, 2-7 1-2 -1-6 O’O -3-5 -1-6 0-0 11-4 Precipitation of Proteids by Certain Alkaloid Eeagents. — Tannin. — According to Almen a solution composed of 4 grammes of tannin, 8 c.c. of acetic acid (25 per cent.), and 190 c.c. of dilute alcohol (40 to 50 per cent.) gives a precipitate in solutions of albumin, albumoses, or peptones containing 1 part in 100,000, after standing for twenty-four hours. The precipitates are soluble in excess of the reagent. Mallet makes use of tannin in his method of separating amide bodies from proteids (p. 167). Mercuric Iodide with Potassium Iodide, added to a faintly acid solution of mixed proteids, gives a precipitate which, according to Neumeister, is as complete as that given by phosphotungstic acid. Picric Acid in excess gives a precipitate even in very dilute solutions of albumoses. Peptones are not precipitated (Kbnig). Phosphomolybdic acid is sometimes used in place of phospho- tungstic acid. Including Albumin II. 175 ACTION OF FORMALDEHYDE ON PROTEIDS. MermHc chlonde precipitates ^le same amount of proteid 9iS lG9*d. fiCGfc9 I— t (N 00 08-6 61-6 rH p 01 CO O OO 05 O ^ CO O iH ^ p p kO 05 O iH 60-8 cq p kO Phosphoric Acid. 6-07 CO i> CO uo o kp \Ci 1-52 kO iH CO t-* CO O k£5 CO cq CO CO o o T* o UO p kO CO CO p p CO CO fH cq CO o cq p CO Sodium Chloride. rH 05 fH CO CO HI ?H kA CO kC5 CO 05 »H CO 05 O fH o S' ' o iH rH CO ^ O CO TjH CO ?H kO o o 1 kC5 p cq 0-61 1-59 1-91 1 22-17 ) 1 Glycerin \ r 15-05 ) Carbo- [ hydrate J Ash. 23-61 29-36 o cp 00 rH kO O (M 11-06 iH 00 CO kO o t-f 05 O - kT5 CO 00 p kC5 kT5 7^ Tjl p o i Albumin. : • 00- 1 ko cq p p : T* O kO * rH ■ : CO . . * • 05 rH (N cq iH CO Gelatin. 00 iH w CO CO kp o kp kO 69-0 kO CM r- kC5 l-«» fH 00 ^0 rH iH 00 iH kT5 iH p CO CO CO O p P r^ cq kO p o 1-69 Fat (Petroleum) Spirit Extract. o iH 9^ o CO (p o 05 o OI-O o 00 ko cq

c S PU oc O Zoo Ph cc 30 Pi 0 1 1. Soluble albumin, . 2. Nitrogenous constitu- trace trace 0-08 0-87 0-06 0-69 trace trace ents insoluble in 60 to 64 per cent, alcohol, . 0-21 2-26 0-38 3-61 1-86 18 49 0-25 9-02 S. Albumoses, 0-96 10-34 1-21 18-24 4-16 41-17 0-70 25-27 4. Peptones, 0 to trace 0 to trace 0 0 0 0 0 0 5. P'lesh bases. 6-81 73-38 6 97 65-32 8-97 89-88 1-66 66-31 6. Ammonia, 7. Other nitrogenous com- 0-47 6-06 0-41 4-49 0-29 2-88 0-09 8-25 pounds. 0-83 8-96 1-14 12-47 0-25 2-49 0-17 6-15 As regards the chemical examination of meat extracts in general they remark — 1. Precipibition with 80 per cent, alcohol does not differen- tiate the kinds of nitrogen. 2. Albumoses should be determined by saturating their solu- tion with ammonium sulphate or zinc sulphate. 3. The filtrate from the albumoses should be decolorised with animal charcoal and tested for peptones by the biuret reaction. 4. Ammonia may be estimated by distilling the solution with ignited magnesia. 5. When peptone has been proved to bo absent, the nitrogen in the phosphotungstate precipitate, after deducting the nitrogen derived from gelatin, albumoses, and ammonia, may be ascribed to the flesh bases. The precipitate should stand at least one day. 6. The difference between the total nitrogen and the nitrogen in the form of gelatin -f albumoses -f flesh bases -I- am- monia gives the amount of nitrogen contained in the compounds not precipitated by phospho tungstic acid. BECKMANX’S METHOD OF analysing ‘ peptones/ etc. 199 Application of Formaldehyde to the Analys of Peptones, etc.-E. Beckmann has examined a peptones, commercial ‘ peptones, an general rule Lthod described on p. 175, and exceed the amount of insolube residue in meat extracts does nor 3 per cent. Preparation. Insoluble For- malin Residue. Per Cent. Containing Proteid. Per Cent. Peptone e carne (Merck), . Peptone puriss. (Griibler), . • Peptone from Albumin (Merck), . Peptone sicc. from blood fibrin (Merck), 0-51 trace 11-07 20-50 0-29 trace 3- 60 4- 36 1-45 14-15 13-87 46-49 0- 76 1- 92 0-48 5-96 Hydropeptone (Merck), Kemmerich’s Flesh Peptone, Denaeyer’s Peptone, . _ • Bovril Lozenges peptonised. Liebig’s Meat Extract, . • • ‘ Santa Maria’ Extract (Liebig), Kemraerich’s Extract, Maggrs Meat Extract, Cibll’s Extract (solid), „ „ (liquid), . Armour’s Meat Extract, Bovril Fluid Beef, seasoned. 0- 47 1- 03 0- 84 2- 33 1- 10 1- 05 2- 09 3- 25 0-25 0-55 0-26 0-80 0-20 0- 47 1- 29 Analyses by Alcohol Precipitation.— The fact that different proteids dissolve in different strengths of alcohol has been made the bases of several methods of examining meat eg;racts. In the earliest of these, all that was attempted was to effect an incomplete separation of proteids and gelatinous substances from the meat bases, which are rightly considered to be the most important constituents in meat extracts. 0. Hehner* analysed a number of preparations by this method in 1885. Two grammes of the sample were dissolved m 25 c.c. of water, and 50 c.c. of strong methylated spirit added to the solution. After standing overnight, the clear supernatant liquid was decanted from the precipitate, the latter dissolved * Analyst, x. p. 221. 200 FLESH FOODS. (without washing) in hot water, the solution evaporated in a weighed basin, and the residue dried at 100° C. and weighed. Some of the results thus obtained were : ^ Preparation. Liebig’s E.vtract, Nelson’s Gelatin, Coiuxntrated Beef Tea. English, . English, . English, , Russian, . X, . . Commercial Essence of Beef. English English English, .... Water. Total Solids. Alcohol Precipi- tate. Ash. Phos- phoric Acid. Nitroge 18-70 81-30 5-16 23-38 6-07 7-94 ... 93-19 3-25 none 36-96 63-04 27-40 4-36 1-16 8-25 31-00 69-00 30-30 4-13 1-00 8-36 41-93 58-07 25-50 4-92 1-10 7-52 24-56 75-44 35-40 6-72 0-95 9-89 54-31 45-69 32-30 7*57 2-11 6-79 89-25 10-75 3-07 1-17 0-34 1-36 89-61 10-39 3-74 1-00 0-26 1-36 92-32 7-68 1-99 1-30 0-38 0-79 The general conclusions arrived at by Hehner from a considera- tion of these results were that the amount of ash should be considerable, and should contain 25 per cent, of phosphoric acid, and that the substances precipitated by alcohol should not exceed 25 per cent, of the total dry solids of meat essence, or 44 per cent, of those of beef tea. Kemmerich* made use of fractional precipitation with alcohol of different strengths in order to effect a separation of the nitrogen- ous constituents in meat extract, and by this means found the following quantity of proteids, in addition to flesh bases, in South American meat extract. 1. Gelatin, precipitated by 50 to 60 per cent, alcohol, 6-19 2. Albumoses, precipitated by 80 per cent, alcohol, . 14-76 3. Peptones, soluble in 80 per cent, alcohol. Pre- cipitated by sodium phosphotungstate, . . 12-31 33-26 Kbnig and Bbmer critically examined Kemmerich’s work, but instead of weighing the precipitates as he had done, determined the nitrogen they contained and calculated the proximate con- * Zeit. physiol. Chem., 1891, xviii. p. 409. PRECIPITATION OP ‘peptones’ BY ALCOHOL, ETC. 201 stituents from the result. In this way they obtained considerably lower results than Kemmerich. Albumoses precipitated by 80 per cent, alcohol. 14-16 Gelatin (?) precipitated by 60 to 60 per cent, alcohol. 6-19 Kemmerich, . - Kdnig and Bomer, . I'SS ... 4-50 They found that the filtrate left after precipitation with 80 per cent alcohol gave the biuret reaction, showing that proteids were still present, but considered it questionable whether these were peptones, for on ’ saturating the solution with ammonium sulphate and testing the filtrate there was no biuret reaction, which should have been the case with peptones. . . . . , The following comparative results given by the precipitation with 80 per cent, alcohol, and by ‘ salting out ’ with ammonium sulphate, showed that albumoses were incompletely precipitated by the former process. Liebig’s Kemmerich’s Kemmerich’s Cibil’s 1 Extract. Extract. Peptone. Extract. Per Cent. Per Cent. Per Cent. Per Cent. Total Nitrogen, . 9-32 8-94 9-88 2-77 Nitrogen precipitated by 0-69 105 4-05 0-61 80 per cent. Alcohol, . Corresponding to Albu- moses, 4-31 6-56 25-31 3-81 Albumoses salted out with Ammonium Sul- phsitCj • • • 7-32 9-71 34-44 5-97 By precipitating the nitrogenous constituents with sodium phos- photungstate, and deducting the albumose nitrogen determined in the ammonium sulphate precipitate, a large residue was obtained, which has often been regarded as consisting exclusively of peptones. Liebig’s Extract. Per Cent. Kemmerich’s Extract. Per Cent. Kemmerich’s Peptone. Per Cent. Cibil’s Extract. Per Cent. Nitrogen in Phospho- tungstate Precipitate, 6-27 5-59 8-29 2-00 Albumose Nitrogen, 1-17 1-55 5-51 0-96 Peptone (?) Nitrogen, . 5-10 4-04 2-78 1-04 Krom the method of preparation it was obvious, in the case of 202 FLESH FOODS. meat extracts at least, that so large an amount of peptones could not have been present, and that the meat bases, which, as is well known, are also precipitated by sodium phosphotungstate, must have accounted for a considerable proportion, if not all of the nitrogen assigned to the peptones. From these considerations Kdnig and Bbmer arrived at the con- clusion that precipitation with 80 per cent, alcohol is of no value in determining the kind of nitrogen. They also expressed doubt as to the correctness of the amount of gelatin (precipitated by 50 to 60 per cent, alcohol) found by Kemmerich. They argued that since meat extracts are prepared at low temperature and only concentrated after filtration, the quantity of gelatin could only be excessively small, and in support of this view referred to the experiments of E. Beckmann, who could only find 0‘5 per cent, of albumin and gelatin in Liebig’s Extract by precipitation with formaldehyde. A similar method of examining meat extracts has been de- scribed by J. Bruylant,f who precipitates the gelatin by 40 per cent.* alcohol, albumoses by 80 per cent, alcohol, and peptones by alcohol of from 93 to 94 per cent. The results thus obtained with certain preparations were : — Liebig's Extract. Solid Bovril. Bovril for Invalids. Fluid Bovril. Water, 16-76 19 20 2-36 43-26 Sodium Chloride 2-95 4-60 4-00 9-75 other Salts 18-24 16-20 17-05 6-26 Insoluble in Water (Meat Fibre), . 7-10 8-19 Organic ilatter 62-'o« 6010 64-60 82-06 Total Nitrogen, 9-80 8-85 9-12 4-86 Nitrogen in portion insoluble in water, • * 1-09 1-19 Nitnigen (Ammoniacal, from Uric Acid, (fee.), O-60'l 0-60') 0-46^ O-SO'y Nitrogen, from Lead Precipitate (Non-Proteid Suljstances), . ^ }-fi-n9 0-57 0'^® V4-48 ” j-2-67 Nitrogen, Non-Proteid, from 80 per i cent. Alcohol, 0-15 0--20 0-18 1 0-06 1 Nitrogen, soluble in strong Alcohol, 3-69; 3-29; 3-40; 1-05; Nitrogen from Gelatin, . 0-19) 0-26) 0-121 0-05) ,, „ Albumoses, 0-80)- 8-93 0-95) 3-78 0-76)3-67 0-45)1-83 „ ,, Peptones, 2-94) 2-681 2-70) 1-33) Total Soluble Proteids, . 24-56 23-62 22-40 11-43 Insoluble Albumin (Meat Fibre), • * • • 6-81 7-43 * Forschungs Ber., 1894, p. 423 ; cf. page 199. t Joum. Pharm. Chim,, 1897, v. p. 515. KONIG’S ANALYSES OF FLESH ‘ PEPTONES.’ COMPOSITION OF COMMEKCIAL ‘PEPTONES, 203 In 80 per cent. Alcohol. Insoluble. ■ CO 00 CO . OO • T’ ^ : ^ O C3 03 50 CO ^ 50 ^ ; (M iTf ^ . ^ • TO to O r~ "P b b b OO 52 05 CO T-l Organic Matter. 12 S Si S £ ^ s § g 5 s s s Water. S S3 £ £ s S b o o g o CO j- a a cs C-, I s ao2 . o ^ o pH o >> ^ A o 03 • CQ rzJ ® O o “o o ca O o >, cd c3 • fl _ O 00 *U O) 03 P3 pH ® ^ a ■s- -5 p o <1^ P4 03 03 H £; 03 w m c c3 ^ 03 w 204 FLESH FOODS. The criticisms of Konig and Bomer on Kemmerich’s work are in the main also applicable to Bruylant’s method. At best the separation is not sharp, and variations in the strength of alcohol would alter the proportion of the constituents in each group. In some cases in which the decomposition of the albumin molecule had been carried slightly further, products of lower molecular weight and of greater solubility would be grouped with the peptones although by saturating their solution with zinc sulphate or am- monium sulphate they would be found among the albumoses. Although ^ by alcoholic precipitation concordant results can be readily obtained, which will indicate more or less accurately the degree of hydrolysis which the original proteid molecule has undergone, the method is much less convenient and exact than separations effected by means of zinc sulphate and bromine. Older Analyses of Flesh Peptones. — Konig * gives the foref^oing analyses (see p. 203) of preparations of this class. As the° pro- peptones (albumoses) were estimated by precipitation with ferric acetate, and the peptones by precipitation with phosphotungstic acid, the nitrogenous constituents returned as peptones probably contained a large proportion of albumoses as well as of meat bases. By precipitating the albumoses by saturation with ammonium sulphate Ivbnig obtained the following amount of albumoses and peptones from Cibil’s and Antweiler’s peptones. Albumoses. Peptones. Cibil’s a, 13-71 28-29 M • • • • 6-51 9-62 Autweiler’s .... 47-74 27-10 Schjeming’s Method. — The precipitation of the proteid sub- stances in meat extracts, etc., in the form of distinct metallic com- pounds, is carried out as described on page 171. In a recent communication to the author, Schjeming states that he includes the peptones under the term of ‘protein substances,’ and that he defines them as ‘ proteids not precipitated from a neutral or acetic acid solution on moderately warming the liquid after saturation with a readily soluble sulphate.’ For the saturation he prefers magnesium sulphate, finding that it precipitates the same quantity of proteid nitrogen as zinc or ammonium sulphates. Schjerning’s peptone therefore agrees with Kiihne’s definition of a true peptone (but cf. page 196). * Nahr. u. Gcnussm., II. p. 186. SCIIJERNING’S AN/^LYSES OF MEAT EXTRACTS, ETC. 205 ‘Denuclein,’ he asserts, is not a proto-albumose, since all albu- moses are precipitated from an acetic acid solution by saturation at 30“ to 36° C. with a readily soluble sulphate, whilst denuclein is not thus precipitated. It is rather, as its name denotes, a lower nuclein compound, and possibly a nucleic acid substance._ In support of Schjerning’s position it may be J that in the table of Konig and Bomer’s results (page 198), about 9 per cent, of the total nitrogen in Liebig’s Extract is not classi- fied under the head of albumin, albumoses, peptones, flesh bases, or ammonia, but belongs to other nitrogenous compounds. Some of Schjeming’s results are shown in the subjoined tables : — I. Precipitation with Liebig’s Flesh Peptone. Witte’s Peptone. Liebig’s Extract. 1896. Liebig’s* Extract. 1899. a. SnClo 13-0 13-5 3-0 3-0 10-7 5-5 PbAc2 t t t 34-0 19 2 14-8 b. HgCb 24-8 24-5 34-0 c. FeAcj 57'2 56-6 59-4 25-3 24-7 fi. UAco 65-3 £5-9 55 '9 55-1 36-7 32-3 e. MgSo^ 48-1 48-1 47-2 47-2 15-1 15'1 Allowable Error Per Cent. 0-5 0-8 0-8 0-5 II. Liebig’s Flesh Peptone. Witte’s Peptone. Liebig’s Extract. 1896. Liebig’s Extract. 1899. Albumin L, 13-0 13-5 3-0 30 10-7 5-5 Albumin 11., 3-4 2-5 18-8 1 31 '0 -1-7 -0-3 Denuclein, . 8-4 8'5 12-2 10 '2 9-6 Albumoses, . 32-4 3-2-1 25 ’4 1 21'1 |l7-5 ^ R |l7-5 Peptones, . -1-9 -1-6 -3-5 11-4 / 7‘6 / It is remarkable that the combined amount of the nitrogen from the albumoses and ‘peptones’ should be identical in the two samples. • Unpublished. t The precipitation could not be made. 206 FLESH FOODS. The residual nitrogen representing the flesh bases, amido-com- pounds, ammonium salts, etc., was calculated to be 63-3 per cent in 1896 and 67’7 per cent, in 1899. It is suggestive that Kbnis and Bomer assigned about 10 per cent, more nitrogen to the flesh- bases and found no peptone nitrogen, whilst Schjerning obtained about 10 per cent, of the latter (p. 198). Although in certain cases Schjeming’s process may eventually be found a satisfactory method of fractionating the proteid nitrogen in different organic substances, it suffers at present from the drawback of being new and of yielding results which are difficult to compare with those of older methods. Probably the metallic compounds obtained by it are of a more definite character than those which, like the compounds yielded by saturating the solution with salts, are only separated from one another by a difference in solubility. If this be the case, and if the physiological characteristics of the various proteids precipitated in combination with the metals be determined, a distinct advance will have been made in estimating the comparative value of different meat extracts and similar preparations. CHAPTEE X. THE COOKING OE FLESH. Advantages of Cooking.— The process of cooking has three main advantages ;-(l) It renders the flesh more appetising by the development of certain odours and flavours under the action of the heat ; (2) it destroys animal parasites, and to a ^ certain extent bacteria and bacterial products ; and (3) the flesh is eaten at a temperature more favourable to the action of the gastric Juice. On the other hand, the digestibility of cooked meat^ is consider- ably less than that of raw meat, as was shown by Chittenden and Cummins,* who found that if the digestibility of cooked beef in artificial pepsin solution be taken as 100, that of raw beef may he represented by 1 42 -3 8 . The longer th e cooking has been continued, the greater is the decrease in digestibility. The national economy of invariably eating flesh in a cooked condition is shown by the fact that Berlin employs over 200 trichinse inspectors, and Prussia more than 24,000, as a safe- guard against one of the dangers of raw flesh, t whereas in other countries, such as Italy, France, and England, where pork is, as a rule, only eaten in the cooked state, no special inspectors are em- ployed, and yet trichinosis is of comparatively rare occurrence. In Germany the public is now warned against eating raw meat, even after it has been inspected and passed. The Loss during Cooking. — This depends to a large extent on the method, of cooking. According to Lethehy,| the average percentage loss in weight on boiling is 23; in baking, 31 ; and in roasting, 34. If the meat is placed in cold water which is gradually heated to the boiling-point, the loss is considerably higher, owing to the large proportion of soluble proteids, nitro- genous extractives, and mineral matter, which dissolves before the temperature (50° to 70° C.) is reached, at which the albumin begins to coagulate and to form a protective crust on the surface. Under these circumstances the loss may amount to from 30 to 40 per * Joum. Amer. Chem. Soc.. vi. p. 318 ; cf. page 86. t Der Fleischbeschau, p. 647. + On Food, p. 166. 208 FLESH FOODS. cent (Strohmer). Part of the loss during boiling is due to some of the collagene being converted into gelatine and dissolving, in the water. ° In roasting and baking the constituents of the flesh are retained much more completely than in boiling, and although the loss is apparently greater, it is almost entirely due to water. The fi-mres given by Strohmer* as representative of the average loss in different kinds of flesh on roasting are considerably lower than those of Letheby — viz., Beef, 19 per cent.; veal, 22 per cent. • mutton and poultry, 24 per cent " The Composition of Cooked ^eBit-Roasting.-^Yhen meat is roasted there is a considerable loss in weight, amounting from 25 to 3o per cent, calculated on the original substance. This is mainly due to the evaporation of water and to loss of the substance of the meat in the form of dripping and gravy. By maintaining a high temperature during the initial stages of the process, the juice which first escapes from the meat becomes coagulated on the surface and furnishes a thin glaze, which pre- vents any further considerable loss of meat juice. Some idea of the difference in composition of raw and roasted meat may be obtained from the following analyses. As they repiesent cuts from different joints, they are not, however, strictly comparable : — Water. Nitro- genous matters. Fat. Ash. Beef, raw ,, roasted, .... Mutton, raw (Konii;), . ,, roasted (Mitchell), 71-68 50-82 75-99 45-21 20-52 25-05 17-11 31-84 6-72 21-65 5-77 21-37 1-21 1-45 1-33 1-58 The characteristic aromas of roast meat are due to the partial carbonisation of the meat fibre with the formation of odorous compounds. Boiling. — The change which meat undergoes during boiling differs very much from that which takes place in roasting. The loss in water is much less, but the action of the boiling water on the collagene of the connective tissue causes a large amount of gelatin to be dissolved. The meat also loses much of its extractives and mineral matter, which will be found in the broth. This loss can be obviated to some extent by first placing the meat in boiling * Die Emahrung des Menschen, p. 123. 209 CHEMICAL COMPOSITION OF COOKED MEAT. water, so as to coagulate the myosin of the nauscular tissue, and thus prevent the loss of much of these constituents during the subsequent gentle boiling or simmering. When gravy or soup are required the opposite process is followed, the meat being placed in water of a low temperature, which is gradually heated, though not to the boiling-point. _ i • • + According to Pereira,* the average loss in weight in the joints of beef and mutton boiled for the inmates of the Wapping ware- house was 17-5 per cent., but in Letheby’s opinion this was con- siderably lower than the general average. 0. W. Andrews states that the total loss on cooking should not exceed one-fifth to one-fourth for boiled meat and about one-third for roast meat. Grilling and Frying. — Grilled meat resembles roast meat in many respects, but owing to the more thorough and direct action of the heat, there is a greater loss of water and of dripping, and a more complete carbonisation of the exterior meat fibre. In frying, which may be regarded as boiling in fat, the presence of the latter modifies the direct action of the fire. A. H. Church f gives the following analyses of raw and of cooked mutton chops : — Fresh mutton chop, minus bone — Water, 44‘1 ; albumin, 1'7 ; fibrin (true muscle), 5'9; ossein-like substances, 1’2; fat, 42‘0 j organic extractives, 1'8; mineral matter, I'O ; and other substances, 2 ‘3 per cent. COMPOSITION OF TWO COOKED MUTTON CHOPS. Water. Nitro- genous Matters. Fat. Mineral Matter. Other Substances. I. Chop, including gravy and drip- ping, . 64-0 27-6 15-4 3-0 II. Chop, without gravy and drip- ping, . 51-6 36-6 9-4 1-2 1-2 “Meat is tender if properly cooked before the rigor mortis has set in, but must be kept for some days after that rigidity of the muscles has set in,” if the same degree of tenderness be required. * Letheby, On Food. f Food : Some Account of its Sources, p. 166. J Church, loc, eit., p. 163. 0 -H- 210 FLESH FOODS. Hie Composition of Cooked Fish. — In a recent communication to the Chemical Society * Miss K. Williams gave the following results (among others) of her analyses of different kinds of boiled fish as they would be served at table. The salt cod and herrings were soaked in cold water before cooking, and the sardines well washed in boiling and cold water to remove as much surface oil as possible. When cold the inedible portions (bones, head, skin, etc.) were removed, weighed, crushed in a mortar, boiled in dis- tilled water, the liquid siphoned off and evaporated on a water- bath. The residue was dried until constant in weight and taken as gelatin. As served at Table. Name of Fish. Date. Portion Analysed. Waste — Bones, etc. Gelatin. Water. Nutri- ents. Herrings, Feb. Whole 11-74 0-63 62-99 34-54 Salt herrings, Jan. Flesh • •• 46-03 53-97 Sardines, March Whole 4-91 * • • 42-17 52-92 Sprats, . Nov. 17-90 0-90 61-50 19-70 Salmon, July Section 6-99 0-53 61-06 32-02 Eels, Oct. Heads re- moved 11-66 1-09 63-29 33-96 Mackerel, April Whole 10-51 0-25 65-21 24-03 Cod, Jan. Section 15-99 0-43 63-78 19-79 Salt cod. Feb. 6-13 0-33 67-68 25-86 Haddock, Jan. Whole 35-10 0-80 46-46 17-64 Turbot, . Feb. Anterior and head 31-20 0-59 53-09 15-12 Plaice, . Dec. Flesh ■ • • • • 79-86 20-14 Soles, March Whole 22-02 0-74 61-18 16-06 Oysters, Shell contents ... ... 77-71 22-29 A further analysis of the same specimens of fish gave the additional results given on page 211. The amount of reducing substances was obtained by removing the fat with benzene, and digesting the residue with 100 c.c. of water and 10 c.c. of hydrochloric acid (sp. gr. 1‘125) on the boiling water-bath under a reflux condenser for three hours. The liquid was then filtered, basic lead acetate added, and a current of sulphur dioxide passed through the filtrate. The solution again filtered, concentrated, and washed alumina added until it * Joum, Chem. Soc,, 1897, p. 652. 211 CHEMICAL COMPOSITION OF COOKED FISH. no lonr^er dissolved. After filtration the liquid was evaporated to dryness at 100° C., the residue treated with boiling alcohol, the liquid filtered, and the alcohol removed by evaporation. The residue was dissolved in water, the liquid boiled with animal charcoal and a few drops milk of lime, filtered, and titrated with Fehling’s solution. , „ . . n • ^ AVith reference to the results thus obtained, H. A. Allen points Water in Flesh. Analysis of the Dried Substances. Name of Fish. Ash. Fat (ether extract). Proteids (NX6-25). Reducing Sub- stances as Glucose. Phos- phorus. Nitrogen pent oxide. Herrings, 60-54 5*56 25-25 67 07 ... 0 91 0-66 Salt her- rings, . Sardines, 46-03 19-69 21-90 38-88 17-59 0-89 1-64 44-35 12-03 33-49 55-44 ... 0-97 Sprats, . 75-77 6-42 27-37 57-94 9-88 1-17 0-46 Salmon, . 65-32 4-94 29-43 56-65 14-89 0-51 Eels, 61-08 2-11 44-68 42-88 8-91 0-42 Mackerel, 73-13 4-07 25-73 62-32 13-93 0-85 0-b Cod, 76-32 3-31 1-15 91-55 6-67 0-62 0-63 Salt cod. 72-35 14-26 0-94 76-06 7-14 0 29 0-31 Haddock, 72-37 3-28 1-29 79-57 13 15 0-53 0 43 Turbot, . 77-84 2-41 4-75 84-71 11-81 0-57 Plaice, . 76-86 4-06 9-84 75 16 11-56 0-71 2-78 Soles, 79-20 3-47 1-71 86-71 11-87 0-52 ... Oysters, 77-71 12-16 7-77 65-42 18-32 0-49 ... out that the reducing substances were probably not present as such, but were products of the hydrolysis of gluco-proteids by the hydrochloric acid. He also calls attention to the fact that these analyses do not confirm the popular belief that the amount of phosphorus in fish is very much greater than that of meat. The Effect of Cooking on Animal Parasites. — The experiments of Perroncito (pages 248 and 261) and others have shown that the cysticerci and other larvae of the tapeworms perish below 50° C., trichinae below 69° C., and that no animal parasite found in flesh is capable of withstanding as high a temperature as 7 0° C. If, then, this temperature is reached in every part of the meat during the cooking, all risk from this source is obviated. The Temperatures at which Bacteria Perish. — Bacteria are much more resistant to the action of heat, especially of dry heat, than are the animal parasites found in flesh. Generally speaking, 212 FLESH FOODS. the pathogenic bactei’ia perish at a lower temperature than the non-pathogenic bacteria. Sternberg * exposed pure cultiva- tions of various micro-organisms for ten minutes at different temperatures and obtained the following thermal death points : — Bacillus of Swine Erysipelas, °C. 58 Staphylococcus pyogenes °c. Bacillus pyocyaneus, . 56 albus, . . . 62 Bacillus prodigiosus, . 58 Staphylococcus pyogenes Bacillus fiuorescens, . 54 citreus. 62 Bacillus acidi lactici, • 56 Streptococcus pyogenes Staphylococcus pyogenes 58 aureus. . 54 aureus. The following results have been obtained by other observers at different times : — B. of Swine Erysipelas. — Killed in 5 minutes at 55° C. in pure cultivations, but not destroyed in meat by ordinary cooking (Petri). B. of Hog Cholera. — 15 minutes at 70° C. One hour at 54° C. (Smith). B. of Rabbit Septicmmia. — 15 minutes at 55° C. ; 10 minutes at 80° C. (Ostertag). B. anthraris. — 10 minutes at 54° C., or 20 miimtes at 50° C. (ChauA'eau). 10 to 15 minutes at 55* to 60° C. (Besson). The spores failed to grow after 4 minutes at 100° C. (Sternberg). Spores destroyed by moist heat at 90° to 95° C., but capable of withstanding a much higher dry temperature (Besson). B. of Quarter Evil. — Virulent after an hour at 80° C. Killed after 5 minutes at 100° C. The spores only weakened in a current of steam (Ostertag). B. of Glanders. — Killed at 55° C. (Loffler) ; 55° to 60° C. (Besson). B. tuberculosis. — Perishes at 85° in pure cultivations (Bang). Can withstand 65° C., but perishes at 75° C. (Yersin). In milk, 4 hours at 55° C. ; 1 hour at 60° C. ; 15 minutes at 65° C. ; 5 minutes at 80° C. ; 1 minute at 95° C. (Forster). In the dry state resists 100° C. for 3 hours, and 70° C. for 7 hours (Welch). B. tetani. — Killed after 6 hours at 80° C. ; 2 hours at 90° C. ; and 8 minutes at 100° C. (Besson). The spores are extremely resistant to heat. Streptococcus pyogenes aureus. — One hour at 58° C., and a few moments at 100° C. (Besson). * Bacteriology, p. 147. INFLUENCE OF COOKING UPON BACTERIA. 213 Staphylococcus pxjogenes aureus, 'i 24 hours at 55° C., „ alhis. h oj. 15 minutes at 80° C. (Besson). „ citreus. j Bacillus coli communis.— b minutes at 66 C. (Besson^ Bacillus typhoms.--^rom 10 to 20 minutes at 66 C. m pure cultivations (Besson). Action of Heat on Bacterial Toxines.— The excretory products of pathogenic bacteria consist as a rule of several active prin^ip es They sometimes contain ptomaines apparently identical with those formed by purely putrefactive bacteria, sometimes definite bases only known to be formed by specific bacteria, together with various broken-down products of albuminous substances (toxal- bumoses, peptones, etc.). In some cases definite toxic have been isolated from pure cultivations {cf . page 220), but as a rule the experiments as to the influence of heat have been naacle with the bouillon filtered free from bacteria and containing mixed toxic and harmless products. i i The following are some of the results which have been obtained : Toxic Products of Staphylococcus pyogenes aureus.— activity of the whole toxine is weakened at 58° C. There are two active principles in the cultivations, one precipitated by alcohol and destroyed at 104° C., the other not precipitated by alcohol and unweakened at 104° C. (Besson). Toxines of Tuberculosis and Glanders. — One or more of the active toxic principles in the products of B. tuberculosis and B. mallet are not destroyed at 100° C., as is shown by the method of preparing crude tuberculin and crude mallein. ^ Toxine of Rinderpest. — Destroyed after 10 minutes at 55 C. (Semmer and Kaupach). Toxine of Sheep pox.—\Q minutes at 55° C. (Semmer and Eaupach). Virus of Rabies. — 10 minutes at 60° C. (Sternberg). Toxine of Anthrax. — Weakened but not destroyed at 100 C. Toxine of Tetanus. — Altered by heating at ^65 C. for 5 minuted, and toxicity completely destroyed at 80° C. (Kitasato). The products of several of the bacteria of septicaemia have been shown to be toxic after boiling, and the same remark applies to many of the putrefactive poisons. Hence cooking, even if a temperature of 100° C. were reached in every part of the meat, cannot be regarded as a universal safeguard against bacterial poisons. Lehmann regards flesh infected with the following diseases as dangerous only in the raw or imperfectly cooked condition : — Cysticerci, trichina3, tuberculosis, glanders, actinomycosis and foot- 214 FLESH FOODS. and-moutli disease. He considers flesh infected with splenic fever, malignant mdema, septicaemia, and chicken cholera as dangerous whether raw or cooked. The Temperatures reached in the Ordinary Process of Cookii^. — Some of the experiments which have been made with the object of determining this point are given on page 262, where it is shown that cooking, if thoroughly carried out, destroys trichinae. In further illustration of the fact that heat penetrates hut slowly into the interior of flesh, the experiments of other observers* may be described, llupprecht found that in the ordinary boiling of meat for | hour, as in Saxony, the interior temperature was at most 75° C. at the end of the time, and that, too, only when the meat was in thin strips. In blood sausage the temperature reached in the same time was 66° C. ; in tongue sausage 62‘5° ; in ham 65° ; and in boiled pork 65°. The interior temperature of a rapidly-roasted sausage was only 28‘7° C. Leuckart found that in grilled cutlets and sausages the highest temperature was 62'5° C., and that of roast pork 75° C. Wolffhiigel and Hueppe state that the temperature in the middle of large pieces of meat never reaches 100° C., and in their experiments this temperature was only once attained in the exterior parts. From these experiments it follows that many of the bacteria, if present in the interior of flesh, would probably survive the ordinary processes of cooking. In any case their spores would almost certainly retain their vitality. Fortunately the occurrence of the spores of such bacteria as those of anthrax or tetanus in meat is very exceptional. Changes in the Juices of Meat on Cooking. — According to Strohmer an approximate idea of the highest temperature reached within the interior of the flesh may be formed from the appear- ance of the juice pressed from the cooked meat. He states that if this is a turbid liquid the temperature did not exceed 56° C. If it is clear red the temperature was probably between 50° and 60° C., but not exceeding 65° C. Between 70* and 72° C. the colour of the juice changes to brownish red, and between 75° and 80° C. to yellow. The Public Sterilisation of Infected Flesh in Germany. — Flesh containing only a few cysticerci, or infected with certain diseases, such as swine plague, swine erysipelas, etc., is allowed to be sold in Germany after having been thoroughly disinfected by cooking, under police supervision. For the sale of such meat, and of flesh which has been passed as of inferior quality, though not * Ostertag, Handbuch cler Flcischbcschau, p. 548. PUBLIC STERILIZATION OF INFECTED FLESH. 215 dan^^erous to health, institutions, known as Freihanke have been established in connection with the local m^t inspection m many of the towns, especially in the South of Germany. u meat stamped by the Freibanh is sold at a very cheap rate, and is laro-elv used by the poorer classes. 1 1 i. j The cooking is so arranged that the meat is thoroughly heated throuf'hout. The flesh is divided into thin strips, which are boiled for two or three hours, or until the interior becomes grey in tms process, as ordinarily carried out, there is a considerable loss in nutritive value, and in order to obviate this, sterilisation by means of steam under pressure has been introduced in many places, in Rohrbeck’s steam steriliser, constructed on this principle, evmy part of the meat is brought to a temperature of at least lUU while the meat juices and the flavour are retained to a mucn greater extent than is otherwise possible. CHAPTER XL POISONOUS FLESH. Flesh may sometimes be rendered injurious by contamination with some drug such as chloride of lime, phenol, etc., but, apart from such cases, it may have inherent toxic properties, which may be derived — (1) from some injurious substance eaten by the a,nimal ; (2) from poisonous products secreted by the cells of the living animal ; (3) from pathogenic bacteria or bacterial pro- ducts in the living animal ; or (4) from post-mortem alteration of the flesh by bacteria. Flesh rendered Poisonous by the Food of the Animal.— Numerous instances are on record showing that flesh which is ordinarily wholesome may become more or less injurious from the food which the animal has eaten shortly before being killed. According to Letheby,* the flesh of hares which have fed upon the Rhododendron Chrysanthemum has caused illness, and similarly in Pennsylvania and Philadelphia, pheasants which have eaten the buds of the laurel (Calmia latifoUa) are unwholesome. In fact, Letheby attributes many of the illnesses which have occuri'ed after eating prairie birds imported into this country from America to the nature of the food eaten by the bird. Sometimes in Aus- tralia the flesh of sheep acquires poisonous properties from the animals having fed upon the lotus, wild melon, and wild cucum- ber, the general effects being pains in the limbs, prostration, and sickness. The animals themselves are occasionally, but not in- variably, poisoned by their food. Possibly some of the cases of shell-fish poisoning which happen from time to time are to be attributed to this cause. And it is interesting to note in this connection that the Maletta venenosa, a poisonous tropical fish, is said to be venomous only at the times when the sea is covered with a green monad on which it feeds (Letheby). In 1842 a whole family in Toulouse were poisoned by eating a dish of snails collected from a poisonous shrub, Coriaria myrtifolia. Guenther f states that the poisonous nature of the * On Foods, p. 221. t The Study of Fishes, p. 189. POISONOUS LEUCOMAINES IN FLESH. 217 flesh of most, if not all, of the poisonous fish of the tropics is derived from their food, which consists of medusae, corals, or decomposing s\ibst^nc0s» • Poisons. — Of inorganic poisonous substances taken by the ammal, phosphorus is the only one known to produce more than local effects. In phosphorus poisoning the general symptoms are extravasakon of blood, alteration of the tissues, and fatty degeneration, ihe blood is altered in appearance, and the flesh becomes phosphor- escent in the dark.* Wally considers that, with the exception of phosphorus, “inorganic poisons are never absorbed in sufficient quantity to render the flesh of the animal nocuous. The different instances mentioned above of flesh made poisonous by the food of the animal show that certain organic poisons, apparently of an alkaloidal or glucosidal nature, can produce general symptoms, and this is probably the case with many other organic poisons. Flesh Poisonous from Products elaborated by the Cells of the Living Auima.1 — Formation of Leucomcdnes and Toxines. — In 1882 Gautier showed that just as toxic products (ptomaines and toxines) are secreted by certain bacteria, so by a sort of enzymic action in the living cells the proteids or other nitro- genous compounds are normally broken down into less complex bodies, being finally transformed into urea, amides, hydrocarbons, carbon dioxide, bases, etc. To the basic substances, which are closely allied to ptomaines in many of their reactions and properties, he gave the name of leucomaines,'\ or physiological alkaloids. The process of their formation is primarily a direct hydration, and is regarded by Gautier as an anaerobic fermentation. Most of the leucomaines thus formed are harmless, or only slightly poisonous, but some are extremely toxic, such as neurine and choline. Under certain circumstances leucomaines, or other decomposition products of proteids, may be of such a nature, or produced in such quantity and insufficiently eliminated from the system, as to cause auto-infection. An interesting illustration of this is afforded by the experiments of Professor Mosso of Turin, J who found that the illness caused by over-fatigue is due to the absorption of certain substances into the blood, and that these substances when injected into healthy animals produce the same symptoms. The presence of leucomaines in excess, or of toxines derived from the proteids, is probably the cause of the illness sometimes produced by eating the flesh of over-hunted game or of over- driven cattle. Liebig, in his Letters on Chemistry, mentions a case in which the flesh of a roebuck, which had struggled violently * Andrews, Handbook of Tublic Health, p. 20. t white of ee;g. J Lancet, 1887, p. 1295. 218 FLESH FOODS. after having been caught in a snare, gave rise to symptoms of poisoning. According to Gautier,* pigs have been fatally poisoned through being fed upon the flesh of a horse which had died during its struggles when being broken in, and, like Liebig, he has known of cases of human poisoning by the flesh of roebucks which had died in a state of terror or exhaustion. Gautier t has also confirmed Landi’s statement that when muscle, the cells of which are still living, is taken from an animal and protected from the influence of putrefactive bacteria, the action of the cellular protoplasm continues, and by a sort of anaerobic decomposition causes an increase in the extractives and toxic bases of meat, especially of those belonging to kreatinic and neurinic groups. Simultaneously there is a diminution in the proteids, and the glycogen disappears, but the fat is not appreciably affected. Roger J considers that the toxicity of the extract of normal muscle is to be attributed to toxines of a proteid nature rather than to basic bodies, which are only moderately poisonous. By removing the crystallisable substances by dialysis, he obtained a residue of an albuminous nature, which on injection into rabbits produced symptoms of exhaustion, somnolence, diarrhoea, and death without, or attended only by slight, convulsions. The fact that the extract after being heated to 100° C. did not cause these results was regarded as proof that the leucomaines are not the poisonous substances. Leucomaines which are also known as Ptomaines. — Among the basic substances which have been found both in the products of bacterial putrefaction and amoug the substances elaborated by living cells, probably by the decomposition of lecithins, the following may be mentioned : — Choline [CgHjgNOJ, which occurs normally in the blood, mus- cular tissue, and glands of the ox and other animals. It resembles neurine in its toxic action, but is weaker. Neurine [CgHjgNOg], which usually accompanies choline in traces, and is found in the brain and nerves. It is very toxic, and is regarded by Gautier as the probable cause of the roe of certain fish becoming poisonous at the spawning season. Betaine [CgH^iNOg], which is normally present in many animals, notably the mussel. Trimethylamine [(CHgjgN], which occurs in blood. Keuridine [CgH^^Ng], found in the yelk of egg and in fresh human brain. Cadaverine [CgHj^Ng], isolated in traces from fresh pancreas. Gerontine [CgHj^Ng], found in the liver of an old dog. * Les Toxines, 1896, p. 488. t Ibid., p. 456. t Gautier, ioc, cit., p. 455. POISONOUS FISH. 219 Poisonous Fish.— The following table of fish, certain species of which are known to be poisonous, either invariably or at certain seasons of the year, or after eating certain food, is given by O. W. Andrews * : — a -j t Acanthojpterygii or Spiny-rayed fishes, including (sea- breams) ; Squamipinnes (coral fishes) ; Sphyreenidse (bar- racudas) ; Scomhridds. (mackerel) ; Caranyidm (horse-mac- kerel) ; Acronuridx (sturgeons), and Atherinidse. Pharyngognathi, including Lahridee (wrasses). Physostomi, including Silundas (cat-fish) ; Clupeidse. (her- rings). Plectognuthi, including Sderodermi, e.g., Balistes and Ostra- cion', Gymnodontes (Diodon, Triodon, and Tetrodon). Of the bream family (Sparidm) the Spanish bream {Pagelus erythrinvs) is met with off the shores of New Caledonia and New Hebrides. Its poisonous properties are possibly due to the nature of its food. The Lethrinus mambo is another member of the same family, and is found in the same waters. Its flesh is said to be innocuous when young, but to be very poisonous when full grown. Among the coral-fish the Heniochus macroleptidotus is distin- guished for the brilliance of its colouring and its poisonous properties. It is found in the neighbourhood of coral-reefs and is carnivorous. The barracudas (Sphyraena barracuda) are found in the West Indies, and are usually poisonous. They are large fish, often 8 feet long and 40 lbs. in weight. The Caranx fallax, which is a member of the horse-mackerel family, is said to be wholesome when yoiuig, but poisonous when full grown. It is met with in Australian waters. Different varieties of wrasse are known as parrot-fish from their brilliant colour, and appear to be poisonous from the nature of their food. The cat-fish (Siluridas) are usually found in fresh water, and only those varieties which enter the sea are regarded as poisonous. Their skins are smooth and without scales. According to Guenther f the flesh of certain members of the herring family, such as Clupea thryssa and Glupea venenosa, is always poisonous. Clupea thryssa (the yellow-billed sprat) is exceedingly poisonous, and has been Imown to cause death before being actually swallowed. Tetrodon and Diodon, known as ‘globe-fishes,’ are covered with spines, and have the power of distending their bodies with air into a globular form, and floating on the surface of the water * Handbook of Public Health, 1898, p. 51. t The Study of Fishes. 220 FLESH FOODS. Avitli the underside uppermost and spines proti-uding. Guenther states that some of the species are always poisonous. Balistes, or ‘ file-fishes,’ are so called from the file-like edge of the dorsal fin. They feed on coral and molluscs, from which they probably derive their poisonous properties. The Ost radon, or ‘trunk-fish,’ is protected by a covering of bone-like plates. Like the preceding fish, it is found off the American coast and in Indian waters, and is universally regarded as poisonous. Many of the smaller varieties of these poisonous fish are eaten by larger fish, such as different species of dolphin, conger-eel, etc., and cause the flesh of these to be also poisonous for some time afterwards. In some fish a poisonous substance appears to be secreted only at certain times of the year, as, for instance, in the case of the pike and the turbot, whose roe produces violent diarrhoea when eaten during the breeding season.* According to Letheby the general symptoms caused by eating poisonous fish such as these, are either irritation of the stomach and intestines, with choleraic symptoms, or rapid prostration and convulsions. Flesh rendered Poisonous by Bacteria in the Living Animal. — In addition to certain definite diseases, such as tuberculosis, which may sometimes be communicated through the presence of the specific bacilli or their products in the flesh, there have been numerous obscure cases of poisoning, the symptoms of which resembled, to some extent, those of ptomaine poisoning, although there was no sign of putrefaction in the meat. In some of these cases it is not improbable that ptomaines may actually have been present, and have contributed to the result, since it has been proved that these bases may be formed in cultivations by bacteria other than those usually associated with putrefaction. Thus putrescine has been isolated from cultivations of the Badllus coli communis, cadaverine from cultivations of Koch’s comma bacillus and Finkler and Prior’s bacillus, and methyl-guanidine from the substances elaborated by the bacillus of mouse septicaemia. Bollinger t considers that septicaemia and pyaemia must be regarded as the causes of many cases of poisoning, and he con- siders them as of almost more importance than any other disease, owing to their frequent occurrence. During the four years pre- ceding 1880 he had under his notice eleven cases of wholesale poisoning, and 1600 cases of individual illness, which he con- sidered were undoubtedly the result of septicaemia or pyaemia. In 1874, in Bregenz, fifty-one people were poisoned by the flesh * Guenther, loe. cit., p. 189. t Oatertag, Handbuch der Fleischbeschau, p. 469. FISH CHOLERA — MUSSEL POISONING. 221 of a coiv which had been slaiightered on account of sc|)tic received during calving. A similar case “ Bavaria in which twenty two persons were made ill with choleraic svmntoms The cooked flesh and cooked sausages made from it re' a“o injurious. In another Vrd\^rn' IfeXd Doisoned by beef from a young cow which had been mfecteh with puerpLl sepsis before being flesh showed marked signs of decomposition. In Osterta s experience there were 1500 cases of illness of this nature prfncipally in Germany, during the twelve years preceding 1892 From these and similar cases, which might be cited acf infimtum, there can be but little doubt that a septic condition in the animal is a frequent cause of its flesh having poisonous properties. Fish Cholera.— This is a disease which is epidemic among sturgeon and other fish. Its cause was investigated ^7 Sieber- Schoumow,t who found in the stomach and intestines of the fish a motile and anaerobic bacillus, B. piscicidus agihs, which, on inoculation, produced the disease in healthy fishes. From the sterilised cultivation a very toxic base was separated, which he regarded as contributing to the disorders produced by fish which are normally wholesome, but become poisonous when attacked by this and similar bacteria. , , „ i • i i. j Fischer and Eber isolated from the blood of a carp which had been killed by the impurity of the water a bacillus which was exceedingly toxic to warm- or cold-blooded animals, and which elaborated a poisonous toxine. This, unlike the ptomaine of fish cholera, was destroyed by boiling. j j i Mussel Poisoning. — Severe illness is sometimes produced by eating mussels, the principal symptoms being vomiting, diarrhoea, difficulty in breathing, feeble pulse, prostration, a rash all over the body, dilation of the pupil of the eye, and sometimes swollen tongue and throat. In 1885 there was an epidemic of mussel poisoning in IVilhelmshaven, many of the cases proving fatal in the course of three or four hours. Some of the victims had not eaten more that five or six of the mussels. Konig states that poisonous mussels are usually of a brighter yellow colour, but those of darker colour have also been known to cause the same symptoms. -j The life conditions of the mollusc appear to have a considerable influence on its wholesomeness, for Virchow and Schmidtmann found that when poisonous mussels were left in pure sea-water they became harmless in the course of a month. Similarly * Handbv/ih der FleischbescJiau, p. 475. + Arch. ScicTices biol. de St. Petersburg, 1894, iii. p. 241. 222 FLESH FOODS. M. WolfF and Kdnig * found that mussels placed in the stagnant water of the harbour became poisonous in two or three weeks, while poisonous mussels placed in the neighbourhood of a sluice where the water was frequently changed became harmless again. The mussels collected in January and February were more poisonous than those gathered in November and December. From Wolffs* investigations the poison seems to be chiefly developed in the liver, while the foot, gills, mantle, and eggs are non-poisonous. Schmidtmann t considers that the poison is caused by a definite disease, probably bacterial and communicable. Mytilotoxine. — Brieger j isolated from poisonous mussels a ptomaine or leucomaine to which he gave the name of mytilotoxine. It was accompanied by large quantities of hetaine, which was also found in non-poisonous mussels. The constitution of mytilotoxine is uncertain, but it may be regarded as a methyl derivative of betaine with the formula Possibly it is formed by a diseased condition of the animal from the betaine normally present or by the action of pathogenic bacteria derived from the water. The method adopted by Brieger for its isolation is described on page 316. It was not found among the products of the putrefac- tion of ordinary non-poisonous mussels. The free base is an unstable resinous body with a disagreeable odour. It is extremely toxic, and tlie least traces of its hydrochloride, when injected into animals, produce all the symptoms of mussel-poisoning. Free mytilotoxine rapidly loses its poisonous properties on heating, and on dry dis- tillation yields large quantities of trimethylauiine. Flesh rendered Poisonous by the Action of Bacteria on the Dead Flesh. — It had long been known that an aqueous extract of decomposed animal matters had toxic properties, but it was not until 1855 that the Danish chemist Panum showed that the poison was of a chemical nature, and probably contained several active principles. His results were confirmed by Bergmann, Muller, and other chemists, especially in Germany, but the chemical nature of the toxine was not determined. In 1869 Sonnenschein and Ziilzer extracted from flesh which had been left to decompose for five or six weeks traces of a crystalline basic substance, which gave the (CH,),n/CH ^OH * Kbnig, Nahr. Oenussm., ii. p. 103. t Quoted by Gautier, Les Toxvnes, p. 135. + Virclunu's Archiv, 1889, cxv. p. 483. Virchotd’s Archiv, 1889, cxv. p. 483. 223 SUMMARY OF THE PRINCIPAL PTOMAINES. reactions of alkaloids, and had physiological properties resembling those of atropine. In the following year Selmi that sub- stances of an alkaloidal nature were normally ™ of a dead animal before and after putrefaction ; m 1874 he definitely announced that basic substances resembling the vegetable alka- loids were formed during putrefaction, and gave thern the name of ‘ptomaines’ (7TTw/i.a = dead body); and finally, ml, came to the conclusion that these substances were bacterial products.^ The first ptomaine isolated as a pure chemical substance was collidine, which was extracted by Nencki from a putrified infusion of gelatin. Since then a large number of well-defined ptomaines have been isolated by other workers in this field, among whom may be mentioned Gautier and Etard, Pouchet, Salkowski, and especially Brieger. , . . n i. Summary of the Principal Ptomames.— The principal bases which have been separated from decomposing flesh are given in the subjoined table, in which Gautier’s scheme of classification has been adopted. Monamines of the Fatty Acid Series. Trimethylamine. (CHg)3N. Herring pickle. Di-etliylamine. (CgHgjgNH. Putrid meat extract. Tri-etliylamine. (CgHgjgN. Decomposed cod-fish. Propylamine. CgH^NHg. Decomposing cod-liver. CgH^NHg. Butylamine. C4H9NH2. Do. Amylamine. CsH^iNH.g. Cod-liver oil. Diamines of the Fatty Acid Series. Putresdne, or Tetramethylene-diamine. horseflesh. Cadaverine, or Pentamethlyene-diamine. fish and blood. Neuridine. CgHi^lSTg. Putrid meat, albumin, gelatin. Saprine. CgH^^Ng. Decomposed flesh. do. Putrid Putrid Guanidines. Methylguanidine. C2H7N3. Putrid horseflesh and beef. Aromatic Ptomaines, free from Oxygen. Collidine. CgH^iN. Putrid fish and putrid gelatin. Parooline. CgH^gN. Putrid horseflesh after several months. Corindine. CjoH^gN. Putrid cuttle-fish. Di-hydrocollidine. CgH^gN. Putrid fish and horseflesh. Oxygenated Ptomames. Nmrine. CgH^gNO. Putrid meat on fifth or sixth day. Choline. C5H15NO2. Accompanies neurine. Muscarine. CgH^gNOg. Putrid fish. Betaine. CgH^iNOg. In mussels (leucomaine). 224 FLESH FOODS. Homoinperidinic Acid. C^TI^jNOg. Decomposition of meat fibrin. Mytilotoxine. CgHijNOj. In poisonous mussels (? leuco- maine, cf. p. 222). Mydatoxine. CgHj3'N’02. Putrid horseflesh after nine to fifteen months. Gadinene. C-H.^NO.,. I r. c u • n j Methylgculine^. C,/h,,N02. f especially cod. Jjnnamed Base of Brieger. Accompanies myda- toxine. Aromatic Oxygenated Bases. Tyrosamines. C^HgNO ; CgH^^NO ; CgHjgNO. Decomposing cod-liver. Mydine. CgHjjNO. Decomposing human flesh. Symptoms of Ptomaine Poisoning. — The usual symptoms of ptomaine poisoning are dilation of the pupil of the eye, followed by its contraction, feeble pulse, slow respiration, fever, loss of muscular contractibility, stupor, concisions, and death. The loss of the power of contracting the muscles, even under electrical stimulus, is remarkable, and is a characteristic symptom of poisoning by muscarine, a ptomaine which is found both in putre- fying flesh and in poisonous mushrooms. The ptomaines vary considerably in their physiological action, some being quite inert, while others are fahil even in small doses. The symptoms of flesh poisoning pi’obably vary in kind and degree with the nature and quantity of the bases present, some of which may modify to a greater or less extent the action of the others. Of the monamines formed during the putrefaction of flesh, the methyl amines and ethylamines are only moderately poisonous, tending to produce fever ; hutylamine in large doses produces con- vulsions and muscular paralysis ; and amylamine, which is very poisonous, causes dilation of the pupils of the eye and con- vulsions. The diamines {putrescine, cadaverine, neuridine, and saprine) are either physiologically inert or at most only slightly poisonous. Cadaverine is said to produce inflammation of the mucous membrane. Methyl-guanidine, which may be taken as representative of the guanidine ptomaines, is exceedingly toxic. It produces dilation of the pupils, convulsions, and death within twenty minutes, when injected into a small animal. Of the aromatic non-oxygenated ptomaines, collidine, parvoline, corindine, and di-hydrocollidine are all extremely poisonous. Ccrrindine resembles curare in its efiects, causing paralysis. 225 BOTULISM, OR SAUSAGE POISONING. Di-liydrocollidine produces torpor, muscular paralysis, and convulsions. . . . Of the better-known oxygenated ptomaines, neurine produces salivation, contraction of the pupil of the eye, sudden conyulsmns, and death. Choline resembles neurine in its physiological action, but is much weaker. Muscarine is exceedingly toxic, and in small doses produces salivation, contraction of the pupil of the eye, diarrhoea, convulsions, and death. The action of atropine is antagonistic to the three preceding ptomaines, and is used as an antidote. Betaine is non-poisonous. Mydatoxim is moderately poisonous. In large doses it causes diarrhoea, redness of the eyes, convulsions, and death. Gadinene is not very poisonous, but methylgadinene in sufficiently large doses produces symptoms of paralysis. An unnamed base of Brieger (CyH^t^NOg), which was found accompanying mydatoxine in putrid horseflesh, has poisonous properties resembling those of curare. Botulism or Sausage Poisoning. — Like the attacks of trichinosis, cases of botulism have been most frequent in those parts of Germany where, as in Saxony, raw ham and raw sausage are most widely eaten. Sometimes the poisoning has been wholesale, as in the Chemnitz cases, where, in 1879, 241 individuals were poisoned by Mettwurst, and where, seven years afterwards, 160 persons were poisoned in the same way. Ostertag * mentions smaller outbreaks of the same kind since 1886, as, for instance, in Dresden (11), iu Gerbstadt (over 50), and in Gera (30). The characteristic symptoms of pure botulism appear after a period of incubation of from eighteen to forty-eight hours. They commence with a feeling of uneasiness and pressure in the stomach, followed by vomiting and, occasionally, diarrhoea, with faintness, disturbance of the vision, muscular flaccidity, and collapse. When the case ends fatally death results in from four to eight days. When the toxine of B. hotulinus is the sole contributing cause of the illness, fever and mental disturbances are not among the symptoms. The mortality is very high, and, according to Senkpiehl, out of 412 cases recorded between 1789 and 1886 there were 165 deaths. Eber regarded both sausage poisons and ptomaines as toxigenic substances, not toxines. Under the term ‘ toxigenes ’ he grouped those chemical products which, on injection into an animal, are not poisonous until they have been modified by the vital activity of the cells. He compared them with certain inorganic substances, such as sodium iodide, which, when injected into an animal, produce no ill effects for some six or eight hours. * Loc, cit,, p. 502. Schneidemuhl, Cent./. Bakt., 1898, p. 577. P 226 FLESH FOODS. The origin of the poison remained unexplained for years, although it had long been recognised as distinct from that derived from ordinary putrefaction. Hilger * was the first to isolate from the intestines of six persons who had died from sausage poisoning a semi-fluid substance with properties resembling those of curare, and Tamba found a similar substance in liver sausage exposed to the air. Haupt believed that the disease was produced by the decom- position products formed by B. protem mirabilis, but Ostertag pointed out that the symptoms of botulism did not agree with those produced by the inoculation of cultivations of that micro- organism. In 1895 van Ermengem isolated, from the body of a victim to sausage poisoning, an anaerobic bacillus, the cultivations of which produced the same symptoms. The characteristics of this bacillus, which was never found in putrefying substances, are given on page 278. Brieger and Kempner f have recently isolated from pure cultiva- tion of B. hotulinus a toxine w’hich they regard as closely related in chemical composition to the toxines of diphtheria and tetanus. The dried toxine kept well, and was found to produce all the symptoms of sausage poisoning. From putrefying liquids or flesh no poisonous products with the same pathogenic properties could be isolated. The symptoms caused by products of the coU species, to which flesh poisoning has often been attributed, had no specific effects, and the cultivations of Gaertuer’s B. enteritidis produced only very slight symptoms. The toxine of B. botulinus is rendered inactive by being heated to 60' or 70’ C. Kempner J found that by injecting gradually-increasing doses of the toxine into goats the animals were rendered immune, and that guinea-pigs treated with the blood serum of the immune goats were made capable of withstanding a dose of the toxine 100,000 greater than one which, under other circumstances, would have been fatal. * Konig, Nahr, Oemissm., ii. p. 103. t Cent./. BakL, 1898, p. 619. t Zdt. f. Sijg., 1897, xxvi. p. 481, CHAPTER XII. THE ANIMAL PAEASITES OF FLESH. To give even a brief account of all the internal parasites found in different animals would require much more space than can be spared for it here, so that, with a few exceptions, the various organisms described in this chapter will be limited to those connected directly or indirectly with flesh considered as human food. Internal parasites, or Entozoa, may be defined as lower organ- isms, which either in an immature or adult condition inhabit the tissues or canals of different organs, or of the muscle or skin of higher animals, either in a free or encysted state. They may be grouped into three main divisions : — Protozoa. — Low organisms whose bodies are composed of con- tractile tissue and are usually without definite structure. Infusoria. — Microscopic organisms provided with mouths, or at least suction tubes, such as, for example, Ceixomonas intestinalis, found by Davaine in the excreta of a cholera patient. Helniinthia, or true intestinal worms. Of the first class the parasites in the sub-order of Sporozoa are of primary importance in the examination of flesh and flesh pro- ducts, and of the third class the three orders — Cestoda, or tape- worms ; trematoda, or flukes j and nematoda, or round worms — likewise require special attention. SPOEOZOA. These form a class in the sub-kingdom of Protozoa. They are unicellular organisms devoid of definite progressive organs {pseudo- podia or cilia), but often provided with an organ of attachment. Their food is absorbed by endosmosis, and their whole lives are spent as parasites. When adult they reproduce their species by the formation of spores {psorospermim) in their interior. Within these spores are formed small sickle-shaped bodies, from which are 228 FLESH FOODS. developed new parasites. The organisms of this class most com- monly met with in the examination of flesh are the so-called ‘ psorosperm saccules,’ the formations known as ‘ Miescher’s tubes,’ and the coccidia with which rabbits are often affected. ‘Psorosperm Saccules.’ These sporozoa, first discovered by J. Muller, are found in the muscle and on the skin and gills of fishes, and when visible to the naked eye have the appearance of small white specks. They vary very considerably in size, some being microscopic, while others are several millimetres in diameter. Miescher’s Tubes {Synchitrium Miesclierianum). These curious formations derive their name from Miescher, who first noted their occurrence in the muscles of a mouse. They have since been found to be widely distributed, and are frequently met with in the flesh of the pig, ox, sheep, deer, and other animals. In the normally extended muscle they have the appearance shown in the accompanying figures, but when the muscles are freed from Fig. 19. — Preparation of muscle containing Miescher’s Tubes. {Leuckart.) their insertions and the fibres contract, the tubes become broader and shorter. They have a thick exterior wall of cuticle, and contain a tough matrix of protoplasm, in which are small bean- shaped granules, O’Ol mm. in diameter. In the younger and smaller tubes (0'7 to 1 mm.) transparent balls (probably spores) may often be observed. Miescher’s tubes are usually classed among the sporozoa, but there is some doubt on the point, since no movements have been observed in the stage of development. Perroncito, in his expert- MIESCHER’S tubes. — COCCIDIA. 229 ments on the action of heat on various parasites (p. 248), found that these organisms never showed any signs of movement as tne temperature rose. On the other hand, Leuckart states tha,t by feeding a pig which was free from the tubes on flesh containing them, he succeeded in infecting the animal, and its muscles were subsequently found to be full of tubes. So far as is known these organisms are without pathological significance. ^ They can be readily stained by means of carmine or methylene blue. Marpmann recommends a counter-stain composed of phloxin red 1 part, and methylene blue 1 part, in dilute alcohol. The section from the flesh is pressed between cover glass and dipped in the stain for ten minutes, then washed with alcohol and water, and examined under the microscope. In this way the organism is stained blue and the muscular fibres red. Coccidium Oviforme. This organism may be taken as a representative example of the coccidia. It has been found in invertebrata (snail, etc.), in various mammalia, and in man, but it is most frequently met with in rabbits, where it produces what is known as the ‘coccidial disease.’ The livers of the infected rabbits are often found permeated with white nodules, some of which attain the size of a nut ; and on section a cheesy mass exudes, which contains innumerable numbers of the coccidia. Sometimes the disease becomes epidemic, and the whole of the rabbits in a warren become infected. The secretions of the liver and bile are interfered with, and the tissue of the glands destroyed. The animals become thin and sick, then shortness of breath and convulsions ensue, and finally death. These sporozoa are also known as ‘egg-shaped psorosperms,’ a name which rightly belongs only to the spores formed within them. The Fig. 21.— Coccidia in the Liver of coccidia vary in size from 0‘35 to a Rabbit, one showing psoro- 0-37 mm. iningth, by 0-016 to 0-02 " mm. in breadth. In the earliest stage of their life history these and other coccidia are found in a free state in the epithelial cells, but towards the end of the period of growth they become enveloped in a firm shell, and leave their resting-place and generally their original ho.st. The granular protoplasm is condensed into a mass in the * Human Parasites, p. 199. 230 FLESH FOODS. centre of the capsule, and spores are formed, each containing a granular ball and a sickle-shaped body. In the case of the Coccidium ooiforme the spores are only produced after expulsion with the faeces from the Ix^y of the host, and the further develop- ment proceeds in moist surroundings outside. The spores are round or elliptical, and have a rather thin wall. According to Leuckart * they are invariably four in number. THE CESTODA. This class of parasites includes the tapeworms and allied organisms. They are flat worms devoid of mouth or alimentary canal. The ‘ head ’ or nurse {scolex) is provided with two or more suckers, and in many cases with curved hooks of attachment, by means of which it fastens itself on to the intestinal membrane of its host, which is usually a vertebrate animal. Here it increases joint by joint, forming a long ribbon-like colony, which re- mains attached to the head for a considerable period. The individual sexual segments {proglottides) increase in size, and be- come more mature or ‘ ripe ’ as they become further removed from the head by the formation of other segments. The ripe joints are expelled from the body of the host, and the embryo which each contains becomes a bladder- worm {Cysticercus or Cysticercoid), usually in the muscles or organs of another animal or inter- mediate host. Here it remains quiescent until introduced into the intestine of a subsequent host, where the head of the larva attaches itself to the membrane, and a new tapeworm is produced. Classification of Tapeworms. Leuckart t gives the following scheme of classification of representative Cestoda : — FAMILY: TiENIADiE. DIVISION I. Cystic! (Cystic tapeworms). Sub-genus. — Cystotasnia (Leuckart). 1. Tmnia saginata. 2. T. solium. 3. T. acanthotrias. 4. T. marginata. Sub-genus. — Echinococcifer (AV einland). 5. T. echinococcus. * Loc. cit., p. 202. t Human Parasites, p. 390. CLASSIFICATION OF TAPEWORMS. 231 DIVISIOIT II. Cystoidei (Ordinary tapeworms). Sub-genus. — Hymenolepis. 6. T. nana. 7. T. flavo-punctata. Sub-genus. — 1 8. T. madagascariensis. Sub-genus. — Dipylidium. 9. T. cucumerina. FAMILY : BOTHEIOCEPHALIL.®. Qenus. — Bothriocephalus. 1. B. latus. 2. B. cristatus. 3. B. cordatus. 4. B. liguloides. Usual Hosts op Some Tapeworms. The following table shows the hosts of some of the better-known bladder-worms and their related tapeworms : Larva. Cysticercus cellu- loses, C. bovis, C. acanthotrias, C. tenuicollis, Echinococcus hominis, G. fctsciolaris, C. pisiformis, Ccenurus cere- bralis, Cysticercus T. cucumerinse, Larva of Bothrio- cephalus latus, ,, B. cordatus, Cysticercus ovis. Host. Swine, dog, bear, deer, rat, ape, man. Ox, goat (experi- ment), giraffe. Man, ox (prob- able). Swine, rumi- nants. Ox, sheep, swine, man. Mouse. Hare, rabbit. Sheep, ox, squir- rel. Dog-louse (Trioh- odectes canis). Pike and other river fish. Probably marine fish. Sheep. Tapeworm. Teenia solium. T. saginata, T. acanthotrias, T. marginata, T. echinococcus, T. crassicollis, T. serrata, T. ccenurus, T. cucumerina, Bothriocephalus latus, B. cordatus, (?) T. tenella. Host. Man. Man. Not known, prob- ably man. Dog, wolf. Dog. Cat. Dog. Dog. Dog, cat, man. Man, cat (experi- mentally). Dog, man. Man (?). Family I. — The Tseniadse. — The tapeworms in this branch of the Cestoda have small spherical or pear-shaped heads supported and moved by a muscular proboscis, the rostellum, and provided 232 FLESH FOODS. with four suckers for attachment, and usually with one or more circlets of hooks. The division of the individual segments is well marked, and each retains its enclosed eggs until the proglottis itself is destroyed. The Tmihadae fall naturally into two divisions ; — I. Cystic tape- worms, which at a certain stage of their growth as larvm form bladder-like cysts containing liquid {hydatids). II. Ordinary tape- worms, in which the embryonic body is solid or nearly solid. I.— CYSTIC TAPEWORMS. These can be further subdivided into two more groups. A, “ Those in which the head arises within the embryonic bladder,” and B, “ Those whose heads are budded off from special brood cap- sules attached to the inner surface of the bladder.”* With the exception of T. saginata and T. solium, all the tapeworms of Group A are found in carnivorous animals. T. echinococcus is representative of group B. Group A. Taenia saginata. — General Characteristics. — This tapeworm, also knowTi as T. medio-canellata, T. lata, and T. dentata, is common throughout Europe, Asia, and Africa, and is the tapeworm most frequently met with in Bavaria, Hungary, Italy, and Turkey. W^’lien full-growm it is about 4 metres in length in its contracted state, and from 7 to 8 metres Fig. 22. — Tsenia saginata. (After Leuckart.) Natural size. when extended. It usually has from 1200 to 1300 segments, of which from 150 to 200 are ‘ripe’ proglottides. The middle segments measure from 12 to 14 mm., and those of the neck seldom less than 1 to 1'5 mm. The head is large (1'5 to 2 mm.), and has a flattened crown, in which is a hollow depression. • Leuckart. 233 CYSTIC TAPEWORMS. — T. SAGINATA. It has four suckers, but is devoid of hooks ^3 and 31). Each ripe proglottis is capable of holding about 3500 eggs (Leuckart) The entire colony of proglottides is renewed every three months, and Cobbold* estimates that a single tapeworm can thus distribute annually twelve million eggs. Ci/sHc&)’cus Bovis.—The bladder-worm of T. saginata is jound almost exclusively in the muscles of the ox, cow, and calf, and most of the attempts to rear it in other animals have been un- successful. Zenker, however, claims to have succeeded in the case of the goat, and it has also been known to occur in the giraffe. It is most frequently met with in the facial muscles, and Fig. 23. — Head of Cysticercus of T. saginata, x 25. (After Leuckart. ) Fig. 24. — ‘ Measles ’ in Beef. Two- thirds of the natural size. (,E. Mitchell.) then in those of the heart and tongue, while other muscles (neck, breast, etc.) are comparatively free. It originates by the animal swallowing a ‘ ripe ’ 'proglottis (or its eggs) which has been expelled from the body of the host of the parent tapeworm. In about eighteen weeks the eggs de- velop into completely formed bladder-worms, which, however, continue to grow for about ten weeks. When full gro\vn each * Parasites of Man, p. 12. 234 FLESH FOODS. « s e envelops itself in a long oval cyst from 3 to 5 mm. in diameter. This contains a transparent fluid, within which the retracted head of the worm can be distinguished. The head resembles that of the sexually complete tapeworm in being provided with suckers, but no hooks. It remains quiescent in the cystic state until the animal dies or is killed and the flesh eaten by man, when it attaches itself to the intestines by means of the suckers, and completes its development. ‘Measles’ in Beef. — The muscle containing the encysted bladder - worms, which resemble little white knots, has often been termed ‘ measly’ from its appearance (fig. 24). There is usually a thick well-developed connective tissue around the cysts, and not infrequently the worm is found dead, and the cyst filled with caseous or calcareous matter. When, too, the fluid in the cyst is turbid, instead of clear and limpid, it is probable that the parasite is no longer living. Beef containing hydatids is only danger- ous in the raw or imper- fectly cooked condition. ‘ Measly ’ beef is very prevalent in India, but is not common in this country. Taenia solium. —6?enera? Char- acteristics. — This tapeworm is segments than T. saginata. In an to 3’5 metres in length, but when contracted, as seen in preserved specimens, its length is usually less than 2 metres Its greatest breadth is about 8 mm. It CJ 2 smaller and contains fewer extended state it is from 3 CYSTIC TAPEWORMS. — T. SOLIUM. 235 usually has about 850 segments, of which from SO to _ 100 are ‘ ripe.’ It has a spherical head, about the size of a pm s head, Fig. 26. — Portion of section of Proglottis of Tapeworm [Tsenia solium). X 42. (After A. M. Prideaux.) provided with four prominent suckers, and from twenty-six to twenty-eight hooks. The apex is often marked with traces of a black pigment (fig. 31). As in the case of T. saginata, each proglottis, after leaving the parent colony, is capable of acting more or less like an independent organ- ism (figs. 25 and 26). The term ‘ com- mon tapeworm ’ is used collectively to indicate both this and the preceding tapeworm. Accord- ing to Leuckart, Jews are free from T. solium (of the pig scolex) but are as Fm. 27.— Section of ripe Proglottis of T. solium, with much infected with Sexual Organs, x 8. {Mtov R. M. Prideaux.) T. saginata as the rest of the community. The uterus of a free proglottis is a characteristic structure (figs. 27 and 31). The larva of this tapeworm ((7. cellulosse) is found most fre- quently, although by no means exclusively (c/. Table, p. 231) in the muscles of the pig, where it produces the well-known ‘ measles ’ 236 FLESH FOODS. of pork. Its origin and development take place in a similar manner to that of the ox-hydatid, but it is much more dangerous from the fact that the bladder-worm and tapeworm are capable of living in the same host, and thus, in the case of man, auto- infection with the hydatids, which produce much greater organic ■> disturbances than the tapeworm, is by no means impossible. i ‘ Measles ’ in Pork. — When eaten by a pig, the covering of the ') eggs of the tapeworm is dissolved by the gastric juice, and the { embryo, piercing the wall of the ] intestine, chooses a suitable place in j the muscle, and is gradually trans- j formed into a hydatid, on the inner j wall of which the head is developed. j After three weeks the bladder is the size of a pin’s head, and continues growing until the ninth week, when it is as large as a pea, and the head, on which the suckers and hooks can now be distinguished, is as large as a pin’s head. After three months the neck is developed, and the larva is ready for transference to its subse- quent host. It now becomes en- veloped in a capsule of connective ] tissue, and remains quiescent until i the animal dies or is killed. ’ Unlike the tricMnse, which imbed | themselves in the muscular fibre, the hydatids prefer the con- nective tissue between the fibres. Among the parts most fre- i quently infected are the paunch, heart, tongue, neck, diaphragm, ! and inner side of the thigh. They are least frequently found ; in the liver, lungs, and intestine. ‘ The frequent occurrence of the hydatids in the tongue often enables the owner of a pig to discover them in the living animal, and in Germany such infected swine are often promptly sent off ; to some out-of-the-way place where there is no inspection of meat, • although the practice is forbidden by law.* The cysts formed by the swine bladder-worms are somewhat smaller and rounder than those of the ox hydatids, and have not so grey an appearance. Calcareous degeneration also occurs with much less frequency. The living hydatid contains a clear transparent tiuid in which the white head of the parasite is seen. The walls of the bladder are composed of a semi-transparent mem- brane, and around this the connective tissue of the flesh in which * Fischoeder, loc. dt., p. 164. Fig. 28. — ‘ Measles ’ in Pork. About two-thiids of the natural size. (After E. Mitchell.) SWINE CYSTICERCI. 237 the worm is imbedded becomes thickened, forming an additional layer, so that the cyst has a greyish opalescent appearance (figs. 32 and 33). The head, retracted within the blaader, is Fig. 29.— Swine Cysticercus with head protruded, x 3. (After Leiickart,) Fig. 30. -Ripe egg of Txnia solium, a, albuminou.s enve- lope ; &, remains of yelk ; c, covering of the embryo ; d, em- bryo with embryonal booklets. {Landois and Stirling. ) furnished with four suckers, and a proboscis on which is a double circlet of from twenty-four to thirty hooks (figs. 29 and 31). Fig. 31.— Head, etc., of Teenia solium and T. saginata, and joints of both, those above showing sexual organs. {Landois and Stirling. ) ^ According to Fischoeder,* swine are infected relatively seldom (0'3 per cent.) in countries in which there is a regulated system * Loc. cit., p. 162. 238 FLESH FOODS. of sewage disposal. As a rule only young pigs less than six months old become ‘hosts,’ although hydatids are sometimes found in animals more than eighteen months old. ^ Taenia acanthotrias. — Only the cysticercus of this tapeworm IS known. _ In form it is very similar to C. cellulose, and, like it, is met with in the muscles and brain of man. It is distinguished by the form of its hooked organ of attachment, which consists of a triple circlet of from fourteen to twenty-six rather slender hooks. The related tapeworm is unknown, but probably lives in the hunian intestine. The cysticercus has hitherto only been met with in the human subject, but its occurrence in beef is also probable.* Fig. 32. — Cysticerci from T. solium. Natural size and magnified. a, embryo sac ; b, cavity produced by budding of the embryo sac ; c, suctorial discs and booklets. (Landois and Stirling. ) Fig. 33. — Eiicapsuled cysticerci from T. solium, imbedded in a human sartorius. Natural size. {Landois and Stirling. ) Taenia marginata.— (?eweraZ Characteristics.— Hhm is one of the most common parasites of the dog. It is distinguished from T. solium by the form of its hooks, which are more slender, although of about the same size, and average from thirty-six to thirty-eight in number. Its suckers also are smaller and weaker. It some- times attains a length of 2'5 metres, but, as a rule, does not ex- ceed T5 metres. It has never been found in the human subject. Cysticercus tenuicoUis. — The related bladder- worm of T. mar- ginata is found in the liver and viscera of ruminants and swine, * Leuckart, loc. cit., p. 561, T. MAKGINATA AND T. SEERATA. 239 and occasionally in deer, but its presence m man has never been proved beyond doubt. It has a strong resemblance m appearance to the bladder-worm of the hare (0. pisiformis). It has been found in a very young lamb’s liver, forming pale yellow points visible to the naked eye. At an early stage of their existence the bladder-worms wander through the liver of the animal, forming long passages. . • v As a general rule the bladder-worms do not remain in the iiver until the end of their growth. Most of them pass into the body- cavity before the head (which in this species is formed at a late stage) has developed, and after remaining there for some tirne in a free state form fresh capsules for themselves, which sometimes grow to a great size. Leuckart * mentions that in the museum at Giessen there is one from an ox which is 160 cm. long and 6 to 7 cm. broad, and it is on record that a tenuicolUs cyst measuring 12 inches by 4 has been found in a pig. When flesh containing a bladder- worm is eaten by a dog, all but the head and neck of the parasite is destroyed, and in from ten to twelve weeks the resulting tapeworm has produced ripe proc/lottides. Tsenia serrata. — This tapeworm is also found in the dog, but does not pass into man. It has some resemblance in appearance to T. solium, for which it has occasionally been mistaken. It is distinguished from T. marginata by its larger head (1'3 mm.), which is provided with conspicuous suckers, a rostellum (0‘64 mm.), and a double circle of from thirty-eight to forty-eight larger and more powerful hooks (fig. 34). Cysticercus pisiformis.— This is the corresponding bladder- worm of this tapeworm, and is usually found in the liver of rabbits and hares. On the fourth or fifth day after eating the eggs the liver of the animals will be found studded with small white points resembling tubercles. These gradually increase in size until the third or fourth week, when, like the Cysticercus tenuicolUs, the worms leave the liver for the body-cavity, and eventually become encysted in a fresh position. In the second week the young bladder- worms measure 0‘5 mm. or more, and soon after change their globular form for a more extended one. About the third week they are about 2 mm. in length and 0'4 mm. broad, and begin to develop the characteristic head (fig. 34). As in the case of the coccidia, the cysts within the liver are enveloped in a layer of connective tissue. The effects of this hydatid are not so severe as those caused by the C. tenuicolUs in the liver of the sheep, for the latter, at the time of its exit, is considerably larger. Leuckart states that he has never met with * Loc. cit., p. 577, 240 FLESH FOODS. a fatal case in rabbits, and that after the worms have left the liver the passages close up, leaving eventually only scars. In addition to rabbits and hares, any grass-feeding ruminant may become infected with this hydatid, though cases are not common. Taenia coenurus. — This is the smallest of the three similar tapeworms of the dog. It differs from T. marginata and T. s&rrata in the shape and structure of its head, and in the structure of the sexual organs. The head (O'S mm. in diameter) is small and pear-shaped, and has from 24 to 32 hooks. In the complete Fio. 34. — He&d o[ Cysticercus pisi/ormis. x 30. (After B. M. Prideaux.) tapeworm there are less than 200 joints between the head and the first ripe proglottis, whereas in the case of T. marginata and T. serrata the numbers are about 550 and 325 respectively. The full-grown worms vary in size from 20 to 50 inches. In England not more than 5 per cent, of the dogs become infected with it, but in Iceland it is very prevalent.* It has not been found in the human subject. Coenurus cerehralis. — The larva of T. coenurus is most com- monly met with in the brain cavity of sheep, but it has also been found in the spinal marrow and subcutaneous tissue of sheep, and in the viscera of a squirrel and lemur, f It is a compound parasite. In most normal cysticerci only one head arises from the inner wall of the bladder, but the coenurus can produce an unlimited number, and Eichler has found as many as 2000 in a single * Cobbold, Internal Parasites of Domestic Animals, p. 96. t Cobbold, loc. cit., p. 72. C. FASCIOLAEIS AND T. TENELLA. 241 individual.* The heads, which, at an early stage, only number three or four, rapidly develop in colonies, as it were. Fig. 35 shows a section of the wall of the bladder of a coenurus with some of the heads. Each head is capable of producing a sexually mature tapeworm in the dog in about three weeks. Apart from this characteristic formation of unlimited heads, the bladder- worms are similar in structure to other cystic bladder-worms. They form passages in the brain similar to those made in the liver by C. pidformis, and produce what is kuo'wn as ‘ gid ’ or ‘ staggers ’ in the sheep. The older an animal gets the more immune does it become against the attack of this bladder-worm, and, as a rule, only lambs are infected. With the advance of the disease the flesh of the animal greatly deteriorates. Fig. Zb.-—C(Bnuruscerebralis. Fig. Z^. — Cysticercusfasciolaris X 25. (After L&uckart. ) from mouse, f natural size. {Leuckart. ) Taenia crassicollis. — This is a small tapeworm which inhabits the intestines of the common and wild cat. Cysticercus faseiolaris. — This is the corresponding bladder- worm, and is found in rats and mice, its favourite position being the liver. It is one of the smallest cysticerci, the cyst rarely exceed- ing the size of a pea, and is notable from the fact that its head and body rapidly become too large for the bladder, and are protruded at an early stage of its existence. Owing to its jointed form it was once regarded as a complete taenia, but it has long been proved that the segmented body is destroyed like that of any other bladder-worm when the parasite is taken into its final host, and only the head is left to develop into the adult tape- worm (fig. 36). Taenia tenella. — On several occasions Cobbold f met with, in the human subject, a slender tapeworm which he believed to be the adult form of the bladder- worm of the sheep {Cysticercus ovis), although feeding experiments gave negative results. It difiiered from T. solium in having shorter proglottides, and in the structure of the sexual organs. * Cobbold, loc. dt. , p. 98. t Entozoa of Man and Animals, p. 98. Q 242 FLESH FOODS. Cysticercus ovis. — It has often been asserted that no special bladder-worms are developed in the muscles of sheep, but Cobbold states that on five separate occasions he has detected a charac- teristic bladder-worm in mutton. The ‘ measles ’ were somewhat smaller than the similar cysticerci in pork, and the bladder- worms were quite distinct from the Cydicerci bovis and eellulosm. The head was about ^^-inch in diameter, and was provided with four suckers j-o-j^inch across, and, unlike that of the bladder- worm of the ox, -with a double crown of twenty -six hooks. The neck and head were studded with calcareous corpuscles, which were appar- ently very distinct on this cysticercus. He was unable to prove experimentally to what tapeworm this bladder-worm belonged. Leuckart points out that from Cobbold ’s description of this cysticercus it has a strong resemblance to the C. celluloses of the pig ; but, on the other hand, all Leuckart’s attempts to infect sheep with the eggs of T. solium were unsuccessful.* Group B. Taenia echinococcus. — In the group of the taeuiadse of which this tapeworm is representative, the heads of the larvae are budded off from brood-capsules on the inner srirface of the bladder. This tapeworm, which inhabits the intestines of the dog, wolf, and jackal, is very small, not exceeding 5 mm. in length, and 0'3 mm. in breadth. It has only three or four segments, of which the last is larger than the rest combined. The head is provided with strong, well-defined hooks, usually from twenty to thirty in number. Echinococcus polymorphus or Hydatid Bladder-Worm. — The larva of this small tapeworm has long been known by the name of 'echinococcus' or 'hydatid.’ It develops in the organs of all herbivorous animals, especially in the lungs and* liver, forming conspicuous bladders, which often increase to an immense size by budding internally and externally. Unlike the cysticerci it is com- paratively rarely found in muscle. It is commonly classified into three varieties: — 1. A simple bladder. 2. A bladder containing daughter bladders. 3. Com- posite bladders united by means of connective tissue. The last variety is usually met with in the ox and in man j the two first in ruminants (other than oxen), in swine, and in monkeys. In all three varieties the heads may be present or absent. As a general rule they are developed when the bladder is as large as a nut, but not infrequently at a later period. Thus Leuckart records an instance in which the lungs and liver of a cow contained 150 * Loc. cit., p. 498. ECHINOCOCCUS POLYMORPHUS. 243 echinococci as large as a hen’s egg, aH of which were barren, whereas in other bladders, only 10 mm. in diameter, the formation Fig. 37. — Echinococcus bladder. ( E. Mitchell, after Leuchart. ) of heads had already commenced. Each head is capable of sub- sequently developing into a complete tapeworm, so that one bladder may produce a colony of worms in the dog. In one or other of its forms the echinococcus is a frequent parasite in cattle, and causes con- siderable mortality. In the ox the bladder sometimes reaches a size of 12 inches or more in diameter. The hydatid in cattle is only indirectly dangerous to man, since the tape- worm does tiot develop in the human intestine. But he is readily infected with the eggs of the txnia, and the resulting echinococci often pro- duce terrible effects. Cobbold states that in certain countries, notably Australia and Iceland, the disease is both prevalent and fatal. Liicke* has examined the chemical nature of the echinococcus bladder, and finds that the substance is of a chitinous nature, but differs from the chitin of arthropoda in being less Fig. 38.— Tsenia resistant to the action of boiling water and of echinococcus, x 12. potassium hydroxide. He states that there is a ^ilchell, after marked difference between the amount of ash in young and in old bladders (e-y., 15‘79 and 0*28 per cent. * Leuckart, loc. cit,, p. 630. 244 FLESH FOODS. respectively). He gives the following figures of the elementary percentage composition of the two (omitting ash) : — C. H. N. 0. Old Bladder, Young ,, . . . 45-342 44-068 6-544 6-707 5-1493 4-478 42-9547 44-747 II.— ORDINARY TAPEWORMS (CYSTOIDEI). The taeniad® in this division do not form bladderdike cysts in the larval stage, and the body of the ‘ bladder-worm ’ or cysticer- coid is solid, or nearly solid. With the exception of cysticerci found in birds, such as Piestocystis variabilis in the crow, which appear to be intermediate, since their bodies often contain a little fluid, the cysticercoids are found only in cold-blooded animals, such as fish, worms, snails, and insects. Tsenia nana. — This is a very small tapeworm, 12 to 20 mm. in length. It has a spherical head with four round suckers, and twenty-tw'o to twenty-eight very small hooks. It has hitherto only been found in the human subject in Egypt. The cysticercoid probably inhabits some snail or insect. Tsenia flavopunctata. — This is a tapeworm about 12 inches in length, which is characterised by having a central yellow spot on each unripe joint. Its head is club-shaped, and is devoid of rostellum or hooks. Tsenia madagascariensis. — A tapeworm about 8 cm. in length, only found once in the human subject in Madagascar. Tsenia cucumerina. — This is the tsenia most frequently occurring in dogs or cats, as many as 200 individuals being sometimes met with in one animal. It is from 18 to 25 cm. in length, and its head has a club-shaped projection and four rows of about sixty hooks. It occurs as frequeiitly in the cat as in the dog, and is identical with the varieties T. cctnina, T. dliptica, and T. monili- formis. It is not rare in man. The cysticercoid inhabits the dog- louse (Trichodectes ranis). Other Taeniadee. — Only a passing allusion can be made here to the many other species of tapeworms which have been described, such as, for instance, T. perfoliata of the horse, T. erassi- ceps of the fox from CysHcercus longicollis in the shrew, and T. tenuicollis in the pole-cat from G. taijm. The taenise found in birds are, as a rule, characterised by a w'ell-developed rostellum as in T. paradoza in the oyster-catcher. Other examples of avian tape- worms are T. malleus in the domestic fowl, T. microps in the BOTHEIOCEPHALUS LATUS. 245 capercailzie and grouse, and TAnfundihuliformis mt^e^o^^^^ partridge, and quail. The cysticercoids from which these are developed probably live in different kinds of insects, or in snails. Family II. The Bothriocephalidse, — The parasites belonging to this family of the cestoda are of simpler construction than the tieniadae. The tapeworms attach themselves to their hosts by means of two longitudinal suctorial grooves, but do not possess true suckers or a rostellum, and the head, which is flat and oval, is as a rule devoid of hooks. The segments are less defined than in the more common cestoda, and the openings of the reproduc- tive organs of the individual joints are differently situated. In most cases the larva at some stage of its existence lives in an intermediate host, but never seems to become a true bladdei- worm, although Leuckart states that in some instances the body has an appendage which apparently corresponds to the bladders of the cysticerci of beef and. pork. The larvae develop in the muscle, or more commonly in the viscera or liver of animals associated with water (frogs, or other reptiles, and birds), but especially in fresh-water fishes. Bothriocephalus latus {The Broad or Pit-Headed Tapeworm). — This is the best known representative of this family. It is common in parts of Russia, Switzerland, Sweden, and N.-E. Ger- many, and though rare in England, is said to be indigenous in Fig. 39. — Head of B. latus reared in a cat from the larva from a pike, x 21. (After Braun.) Fig. 40. — Ovum of Fig. 41. — Ciliated embryo B. latus. X 280. of B. latus emerging (After Leuckart. ) from the ovum, x 200. (After Leuckart. ) Ireland.* It has hence been termed the Irish tapeworm. When full grown it sometimes attains a length of 25 feet, and may have as many as 3000 to 3500 short joints. The body is thin, flat, and ribbon-like, and, unlike the taeniadx, the joints are not separated off as separate organisms, but are expelled in connected chains. * Cobbold, Tapeworms, p. 17. 246 FLESH FOODS. The head is long, oval, and pointed, and has t\YO longitudinal grooves, which serve as suckers (fig. 39). The eggs are oval and comparatively large (0'05 mm. in diameter), and have a characteristic operculum. When immersed in water they develop into ciliated embryos, which give birth, as it were, to a higher form of larva (pro-scolex), which has a diameter of 0*045 mm., and is provided with six well-developed hooks, with which it makes its way into the tissue. This develops into a still higher larva (scolex), which becomes encysted in the pike or other river fish, but there is no knowledge as to how the change occurs. Leuckart and others have kept young pike in water with the ciliated embryos without infection taking place, and the former suggests that there may be two intermediate hosts, the embrj’o being eaten by some small aquatic invertebrate animal, which in turu is eaten by the fish. The Higher Larva of B. lotus. — As found encapsuled in the muscle or on the intestinal w'all this larva is an inconspicuous, flat, club-shaped organism from 5 to 10 mm. in length and 2 to 3 mm. in breadth (figs. 42 and 43). The head, which is usually retracted, has suction grooves similar to those of the adult worm. The body is solid, and is studded with numerous calcareous particles, so that the larva has a white appearance. It is not segmented, and, unlike the flesh cysticerci, has no bladder. The capsule in which it envelops itself is soft, and the head often projects outside it, especially in the case of those on the intestinal walls. When removed from the capsule, and placed in warm and moist conditions, the larva moves actively, bending and straightening itself. Leuckart * states that, under favourable conditions, it is capable of existing for eight days outside its host. It has been proved that this higher larva develops into B. latus in man and in the 6at, but curiously enough the tapeworm in the latter is distinguished by having Fig. 42. — Higher larva of B. latus, with head retracted, from pike. X 6. {Leuckart. ) Fig. 43. — Higher larva of B. latus encapsuled. x 13. {E. Mitchell, after Braun.) * Loc. cit., p. 718. 247 B. CORDATUS AND B. LIGULOIDES. th^/uike is the most common intermediate host, the larva also occurs in the turbot, and probably in nnrl trout family As the tapeworm IS very prevalent among t UtrSh/who are great bleak-eaters,* it is not improbabte Kecently t von Schroder has found the larva in the perch. Eigh y fishes from Dorpat were examined, and of these 35 per cent, wei infpcted though only to a slight extent. Bothriocephalus cordatus;— This is not unlike the preceding tapeworm as regards the structure of its joints but is much smaller (about 12 inches long), and has a snaall, broad, hear - shaped hUd. It is frequently found in the dog in (Greenland where it also occurs in the seal, walrus, and man. In this country it is most likely to be met with among the islands on the northern and western coasts. The hig e larva has not been identified, but probably lives in marine fishes Bothriocephalus cristatus.— This is a rare tapeworm of from 8 to 10 feet in length, which is characterised by a crest-like rostellum. S has twice been found in France. Its higher larva is not known. Bothriocephalus liguloides. — This has hitherto only been observed in China and Japan. Malformations of the Cestoda. It is by no means uncommon for abnormal forms of the cestoda to be met with both in the complete tapeworms and, what is of more importance in the examination of flesh, in the larval stage. Thus among the tEeniadse, double monsters have been described, and formation of supernumerary joints is common, especially in the beef tapeworm (T. saginata). The most common malformation m Bothriocephalus lotus is the presence of double genital apertures in the joints. p i The occurrence of monstrosities with more than four suckera and with an unusual number of hooks is not infrequent, both in the tapeworm and its bladder-worm. Thus Klepp f describes one which was the only individual {Cysticercus cellulosae), found in a pig. This had six suckers instead of four, and twenty-eight hooks. Referring to this case Ziirn§ gives a summary of such abnor- malities in various bladder - worms as recorded by difierent observers. Kuchenmeister, he states, describes bladder-worms of * Cobbold, Entozoa, p. 111. t Zdt. Flcisch u. Milch Hyg., 1898, p. 55. X Ibid., 1898, p. 207. § ibid-, P- 228. 248 FLESH FOODS. suckers. Raillet {Notices para- sitol.) hfis observed the deformity in the hare cysticercuf (C It has frequently been noticed in the case of Cyshcercus tenmcolhs. According to Leuckartand Kuchenmeister t le abnoimahty is not rare in Ccenurus cerehrulis, and Bremser has met with a Tsema crassicollis with six suckers. Bladder- \sorms with five suckers have also been described (Gomez). The Temperatures at which Cysticerci perish. It is a matter of great importance to know what is the highest temperature that different bladder-worms can resist, so fs to deteimine what degree of cooking is necessary to render them harmless when encysted m meat. It was formerly believed from mconclusive experiments, that the bladder-worms Sf beef and pork did not perish at 100 C., but Professor Perroncito of Turin in a systematic senes of experiments, the results of which he com- municated to Dr. Cobbold proved that the temperature was much lower. The method which he employed was to immerse the free cysticerci in w^ater, or a dilute solution of sodium chloride, and to raise the temperature gradually. As the water became warmer they continued moving their suckers and probosccs, until when a certain temperature was reached they suddenly became motion- less. As It was then possible to stain the parasites with an aniline colour, there could be no question as to their being dead. The time taken to heat the water was about ten minutes in each experiment. The temperature was raised from 8°-10° C. to 45 -46 C. in six to eight minutes, and from 46° to 50° C. in about one minute. The following is a summary of Perroncito’s princip.al results and conclusions : — 1. Cysticercus cellulosee dies sometimes at 45° C., more frequently at 47 C., and ordinarily at 49° C. In exceptional cases it can resist a temperature of 50° C. for a few moments. Hence if the cysticercus be gradually heated to 60° C., and maintained at that temperature for a minute, it undoubtedly perishes. 2. Cysticercus bovis perishes betw^een 44° and 45° C., and in any case is unable to withstand a temperature above 46° C. 3. Cysticercus pisiformis of the rabbit sometimes perishes between 45° and 46° C., but usually becomes motionless at that temperature, and dies at 47° to 48° C. 4. Cysticercus tenuicollis dies at 49° C. 5. The scolices of Coenurus cerehralis die at 42° C. 7. The scolices of the cysts of Echinococcus polymorphus usually perish between 47° and 48°, and never resist a temperature of 50 C. A number of similar experiments were also made with different INFLUENCE OF TEMPEKATUEE ON CYSTICERCI. 249 species of complete tapeworms. Tsinia cucumerina dies at 43° to 45 C. ; T. perfoUata of the horse at 45° to 50° C., and T. serraia at 50° C. n , ^ From these results Perroncito concluded that ‘measly meat is quite harmless when it has been cooked so that the temperature throughout is maintained at 50 C. for five minutes. His con- clusions were confirmed in a very practical manner by some of his pupils, who voluntarily ate some infected meat before and after being heated to that temperature, with positive results in the first instance and negative results in the second. Leuckart points out that in dishes which are rapidly cooked, such as sausages and cutlets, the temperature required to destroy the cysticerci may not be reached in the interior of the flesh, and that this would account for some of the cases of tapeworms in persons who have never eaten raw meat. According to Cobbold the ova of tapeworms do not lose their vitality when exposed to the action of frost. From the experi- ments of Braun on the larva of the B. lotus (p. 247), and from the observations of others on the cysticerci in beef and pork, there appears to be little doubt but that bladder-worms can withstand a considerable degree of cold. Eecent experiments, however, have shown that prolonged refrigeration is fatal to cysticerci in flesh. After being kept for twenty-one days in a chamber in which a constantly low tempera- ture was maintained the cysticerci were readily dissolved in artificial digestion experiments, which would not have been the case with living cysticerci, and no tapeworms were produced when animals were fed with the meat which contained them. By a recent Prussian regulation (November 1897), the flesh of oxen and calves which are only slightly infected with cysticerci {i.e., does not contain more than ten living parasites) is allowed to be sold xmder police regulation, provided it has been either — (1) thoroughly cooked, or (2) kept for twenty-one days in a pickle containing 25 per cent, of salt, or (3) kept for twenty-one days in a suitable refrigerating-chamber, in which the temperature is from 3° to (at most) 7° C., and in which the amount of moisture in the air has not exceeded from 70 to 75 per cent. Influence of Putrefaction on Cysticerci. Cobbold* states that cysticerci have been found alive in all parts of a leg of pork which had not become putrid twenty-nine days after the pig had been killed. In a similar experiment on veal the cysticerci were all dead in fourteen days. According to Fischoederf they lose all power of development when flesh is left * Entozoa, p. 70. f Leitfaden der Fleisclibeschau, p. 167. 250 FLESH FOODS. for three weeks, even without salting or pickling. Leuckart * also found that bladder-worms perished during putrefaction of the flesh containing them. In midsummer they became flabby and turbid in eight days, although in autumn and winter they were alive and in motion after being kept for fourteen days at a tem- perature of 5° to 8“ C. Cysticerci in Ham. — From Leuckart’s experiments * it appears that ham prepared from ‘ measly ’ pork is quite harmless. During the smoking the fluid in the bladder of the scolex disappears, the body becomes turbid, and collapses, and even in fresh ham cysticerci were never found alive. Kiichenmeister obtained similar results in his experiments. Ostertag f states that they also perish when the meat is kept in brine for twenty-four hours. The Examination of Flesh for Cysticerci. The beef and pork cysticerci and the larva of the Bothriocephalm latus can often be detected by the naked eye in sections of the flesh, but in sausages and other meat preparations the aid of the microscope is necessary. Kissliug I treats the selected portions of the sausage with a dilute solution of potassium or sodium hydroxide (sp. gr. IT 5), BO as to isolate the cysticerci. Schmidt Mulheim advocates the use of acid pepsin for the same purpose. The flesh is treated with a solution of 100 c.c. of 0'5 per cent, hydrochloric acid and 5 c.c. of glycerin pepsin. When cysticerci are present the surrounding tissue is dissolved, and the heads of the parasites sink to the bottom of the liquid, where they appear like minute grains of rice. In order to determine whether the cysticerci which may have been found without chemical treatment of the flesh are alive or dead, the condition of the liquid in the bladder should be noted {vide supra). As a further test they may be isolated and examined micro- scopically by Perroncito’s method {ct. p. 218). The parasite is placed in water in a cell on the slide, the temperature gradually raised to 50° C., and an observation made whether any movements occur during the warming. The staining test is also a valuable criterion. The living bladder-worm, and more especially its head, cannot be perma- nently stained with luematoxylin or carmine, whereas the tissue when dead readily retains the stain. * Die menschl. Parasiten, p. 634. + Haixdhuch der Fleischbcschau, p. 269. J Zeit. Fleischu. Milch Syg., 1896, vi. Heft. 4. THE OCCUREENCE OF LIVER FLUKES. 251 THE TEEMATODA, OE LIVEE FLUKES. The parasites commonly known as ‘liver flukes’ have con- siderable external resemblance to the isolated proglottides ot tapeworms. They are flat, leaf- shaped organisms, provided with suctorial apparatus, and sometimes with hooks of attachment. The only members of this group which need be described here are two belonging to the distomata. These have two 44^ — Common Liver Fluke, suckers, a mouth, and a digestive Natural size. {Leuckart.) apparatus, and the embryos are devel- oped in an intermediate host. Distomum hepaticum. — This is the common liver fluke, which was first described by Gabucinus in 1647. When sexually mature it is a large, hermaphrodite parasite, sometimes as much as an inch in length. Its body is long, flat, and oval, and covered with cuticle studded with rows of spines. The eggs are large and oval, and develop in water into globular embryos, which undergo a further metamorphosis in the body of the fresh-water mollusc {Limnseus), where they become the higher larvae of the fluke. These higher larvae, or cercaria, are colourless, and have a tail appendage, by means of which they can swim about in the water. After a time they encapsule themselves on an aquatic plant, or a stick or a stone, and wait until they are swallowed by a higher animal, when they penetrate into the liver or other part of the body and become complete liver flukes. They are most common in the sheep and ox, but have been found in many other herbivorous animals, including the elephant, pig, hare, rabbit, and kangaroo. In man they are also met with occasionally, the cercaria having probably been swallowed with water-cress or some other plant. On several occasions they have become almost epidemic, causing great mortality. For example, Leuckart states that, in 1873, 33 per cent, of the total sheep in Alsace-Lorraine were destroyed by them ; and in 1882 not less than a million sheep are said to have perished in the southern province of Buenos Ayres from their attack. Distomum lanceolatum. — This is the only other liver fluke of common occurrence in domestic animals in this country. It is much smaller than the last parasite, being only 8 to 9 mm. in length. It has a thin, lancet-shaped body, with pointed ends, and differs considerably in its internal construction. It undergoes a metamorphosis similar to that of the common liver fluke, and is often found associated with it in the liver. 252 FLESH FOODS. Occasionally individuals of both kinds of fluke make their way into the lungs, where they form a hard cyst containing a dark- brovm, turbid liquid, within which the parasite can be dis- tinguished. They may also become encysted in other organs, such as the spleen, or even in the muscles. In the stage of development in which they occur in flesh they are not injurious to man. Other Liver Flukes. — A passing reference may be made here to D. Rathouisi, which resembles D. hepaticum, and has been found in the human subject in China ; to D. pulmonale, a thick, plump parasite found in the lungs of animals and men in China, Japan, and Corea; to D. crassum, the large human fluke; and to Fasciola gignntea of the giraffe. THE TRICHINA SPIRALIS.* — This parasite, which belongs to the Nematoda, or round worms, is the only member of the order which need be described at length in the present work. It was probably first discovered in 1822, when Tiedemann noticed certain capsules in muscles which he described as ‘concretions.’ In 1833 Hilton came to the conclusion that these ‘concretions’ were of a parasitic nature, a view which was confirmed in the following year by Paget, who found the worm in the cyst. In 1835 Owen named and described it, but it was not until 1860 that Zenker proved the connection between the trichina and the terrible disease now known as trichinosis. Finally, its life history has since then been fully investigated and described by Virchow and by Leuckart.f Life History of the Trichina. — "When an animal eats flesh conbiining living, encysted trichinje, the calcium carbonate of the capsule is dissolved by the gastric juice, and the young worms, set free, rapidly grow into adidt worms in the intestines, where in the course of a few days the females produce young, and then die. These young trichinm {embrijos) penetrate into the muscles of their host in enormous numbers, and, having chosen a suitable spot, each coils itself up and becomes surrounded with a cyst, which in the course of a few months becomes calcified. Here it remains quiescent until the flesh is eaten, when, like its parent, it develops into the sexually mature parasite. A distinction must thus be made between the intestinal trichina) and muscle trichium, the latter being the immature stage of the former. Intestinal Trichinm. — These minute worms have been found or induced to live in the intestines of man, the pig, wild-boar, dog, rat, mouse, calf, lamb, foal, rabbit, guinea-pig, birds, and other * From the Greek dpil ( = hair). t Cobbold, Human Parasites, p. 31. INTESTINAL TKICHINiE. 253 animals. The body is round and thread-like, pointed in front aiid blunt behind. The mouth opens into a canal leading to the oesophagus, which is surrounded by a series of connected bla^ei- like cells containing granular protoplasm. These extend mo than half the length of the body, and are known as the cell- structure.’ Kuchenmeister and Ziim* consider that this Fig. 45. — Immature Female Trichina, x 360. E. Mitchell.) characteristic structure probably fulfils the function of glands. The oesophagus is continued into a stomach cavity, which opens into an intestinal canal. The organs of generation are distinct in the two sexes. The full-grown male measures at most 1 J mm. in length, and is provided with two external hooked claws towards the posterior part of the body. The female is considerably larger, averaging from to 4 mm. in length. The muscle trichime develop into intestinal trichinas in from thirty to forty hours, and in six or seven days the females, which considerably exceed the males in number, * Lie thierischeni Parasiten im Mensehen, p. 453. 254 FLESH FOODS. begin to produce young, and continue to do so until the sixth or eighth week, when they die. The male trichinae die at a much earlier period. Embryo Trichinx. — The young trichinae or embryos are brought forth alive, each female producing some 1500 or more. They are only about O'Ol mm. in length at the time of their birth, but rapidly develop, and when about 0T2 to 0T6 mm. long, pierce the walls of the intestine, pass into the body cavity, and thence into the muscles. A later view * is that the female deposits the young not in the intestinal cavity, but in the walls of the intes- tine itself, whence they pass with the lymph secretion into the blood, and so are directly introduced into the muscles. The greatest number of wandering trichinae are met with in nine to twelve days after the infection of the host. Dp.velopment of Miiscle Trichinae. — After the young trichinae have penetrated into the selected muscular fibres they remain quiet for about fourteen or sixteen days, in order to complete their growth. When about 1 mm. in length they coil themselves into a spiral or 8-shaped figure. The space in which they lie becomes a wide, spindle-shaped opening, within which a cyst is gradually formed, commencing about the eighth or ninth week and being completed in the twelfth or thirteenth w^eek. Form of the Muscle Trichina. — The muscle trichina measures at the most 0"8 to 1 mm. in length, and 0'03 mm. in breadth. The front part of its body is much narrower than the back. The ‘ cell-structure ’ is plainly visible, and although the sexual organs are very rudimentary, it is possible to distinguish between the immature male and female. Hosts of Muscle Trichinae, — The muscle trichinfe can develop in the same animal as that in which the intestinal trichinae flourish, with the curious exception of birds, in whose intestines the adult worm will live, whereas the larvae have never been found in their muscles. They occur most commonly in the pig, into which they are probably introduced through rats, in which the intestinal trichinae are said to swarm. The whole of the striated muscles are liable to be attacked, with the exception of the heart muscles, in which only in rare instances have single individuals been found. The favourite muscles are those of the diaphragm, tongue, eyes, throat, paunch, and thigh. According to Leuckart the muscular fibres soon lose their structure, the fibrillee being broken down into granular matter, and the sar- colemma eventually thickening and withei'ing up. Encysted Trichinae. — The capsule in which the muscle trichina envelops itself is an oval or lemon-shaped cyst about 0'3 mm. * Fischoeder, Leitfaden der Fleischbeschau, p. 214. 255 ENCYSTED AND CALCIFIED TRICHINAE. in lent^th by 0-25 mm. in breadth. It has a sharply outlined double® border, and contains a liquid in which are granules, and within which the coiled worm When the animal in which the trichina is encysted is in „ dition fat cells are sometimes deposited at the extremity ot the Fig. 46. — Encysted Trichinse in Human Flesh, x 33. (After Prideaux.) cyst. As a general rule only one individual is found within a cyst, but in cases of strong infection the cyst may contain as many as six trichinse. , j After about six months the cysts become calcined, at nrst towards the ends, and the whole cyst may be enveloped in a cal- Fig. 47.— Calcified Muscle Trichina with Parasite faintly visible. X about 60. (After Long and Preusse.) careous deposit in the course of sixteen or eighteen months. It then appears dark throughout, and the trichina is only faintly visible or is quite invisible until the calcium carbonate of the cyst is dissolved with acid (figs. 47 and 48). 256 FLESH FOODS. ]\Iiiscle trichinse can live encysted in flesh for many years. For example, they have been found alive and capable of development 11| years after their first invasion of the muscle, and Tungel* com- puted that some he discovered alive in human muscle must have been encysted for 13^ years. Fig. 48.— Calcified Muscle Trichina, with Parasite invisible. X about 60. (After io?igr and PrciMse.) At the same time it is probable that the trichina usually dies at an earlier stage, its body undergoing fatty or calcareous degenera- tion, and the calcification may be so complete that when the calcium carbonate is dissolved with dilute acid nothing remains of the original worm (figs. 49 and 50). Fig. 49. — Dead calcified Trichina. Fig. 60. — Dead calcified and (After ZeuctorL) disintegrated Trichina. (After Leuckart. ) Effect of the Trichinae on the Host. — In the pig, which is the animal most frequently attacked by the muscle trichinse, the symptoms of the disease are often not very severe, and the animal may show no signs of the infection. Only in exceptional cases do the worms develop so rapidly that death ensues. In human beings, * Kiichenmeister and Ziirn, loc, cit., p. 456. DETECTION OF TRICHINA. 257 however, the results are generally much more serious, the wandering trichinae causing sharp pains in the muscles, flaccidity of the limbs, fever, peritonitis, paralysis, etc., and, when many of them have been eaten, death may rapidly ensue. In some cases, however, the acute symptoms cease when the trichinae have become encys e , and the patient may then regain his normal health. Number of Trichinae in Infected Flesh. Cobbold states * that in an outbreak of trichinosis in Cumber- land in 1871, the pork which produced the epidemic contained upwards of 80,000 trichinae in one ounce, and from this he calculates that one pound of such flesh would be capable of producing some 400,000,000 flesh worms in the subsequent human bearer. Leuckart calculated that the flesh of an infected cat contained 325,000 trichinae, and in another case found 1500 individuals in one gramme of flesh. Cobbold also computed the number in the total muscles of a man who had died of trichinosis at from 90 to 100 millions. The Detection of Trichinge in Flesh. Method of Sampling. — In taking samples from isolated pieces of meat such as ham, pieces about the size of a hazel-nut are cut out in the longitudinal direction of the muscle flbres, and as near as possible to where the muscle is attached to sinews or bones. Where the whole animal is being examined, special attention must also be paid to the muscles in which the trichinge most fre- quently occur (p. 254). In examining sausages Fischoeder f recommends the cutting of four thin slices from each kilogramme and picking out with a needle, for microscopical examination, all particles which from their paler appearance and finer fibres appear to consist of pig’s flesh. In the case of American hams the test sections should be taken from the deep-lying muscles. Trichinge are not foimd in the fat. Microscopical Examination. — For the microscopical examination thin sections of the samples are made parallel with the fibres. These are placed on the object glass, with a cover glass pressed down on them, and examined under an amplification of twenty or thirty times. The Compressor. — In order to make them completely transpar- ent, and to examine a number of preparations rapidly, Fischoeder advocates the use of a compressor (fig. 51). This consists of two glass plates from 12 to 15 cm. in length and about 3 to 5 cm. broad, which fit accurately upon one another, and are connected by means of two delicate adjustable screws at the ends. The com- pressor is divided into twenty-four equal fields by means of twelve * Enlozoa, p. 156, t Loc. cit, p. 224. U 258 FLESH FOODS. transverse lines on the lower plate, and a broad opaque band on the upper plate. This apparatus is not applicable with the higher powers of the microscope, but serves its purpose very well with the low powers. The various thin sections are placed in the numbered divisions of the compressor and the screws gradually tightened until the flesh becomes quite transparent. Treatment of Opaque Sections. — In the examination of fresh juicy flesh, clear preparations are readily obtained without any other treatment than pressure. But in other cases a special treatment with a reagent is necessary. Thus, to dried or smoked flesh is added either a drop of an 0-75 per cent, solution of sodium chloride, or of 3 per cent, acetic acid, or of 30 per cent, potassium hydroxide mixed with three parts of water. Glycerin is also sometimes useful in rendering the preparation transparent. hen a substance resembling the trichina cyst in appearance is found, it should be carefully examined with higher Fio. 51. — Fischoeder’s Compressor. powers, after treatment with acetic acid to dissolve the lime, in order to determine whether a trichina or parts of a trichina are contiiined within it. Treatment of the Flesh with Pepsin, — Schimdt-Mulheim’s method of isolating cysticerci (page 2-50) by treating the flesh with an acid solution of pepsin is also applicable to the detection of cncapsuled trichinte, the cysts falling to the bottom of the vessel. Examination with the Ront^2 (Gautier), C5H46N2 (Brieger). This base, which appears to be isomeric with the two preceding ptomaines, was isolated by Brieger from decomposing human flesh. Isolation and Separation from Cadaverine and Putrescine. — The hydrochlorides are dissolved in hot alcohol, in which that of putrescine is less soluble. The filtrate is slightly concentrated, and platinum chloride added. The cadaverine platinochloride crystallises out first in an almost pure state, and then, on con- tinued concentration, the sapriue platinochloride is gradually deposited. Differences from Cadaverine. Platinochloride, Hydrochloride, Aurochloride, Cadaverine. . Soluble with diflBiculty in water. Crystallises in rhombs. . Gradually deliquesces on ex- posure to air. . Crystallises in readily sol- uble needles. Saprine. ‘ Readily soluble in water. Crystallises in parallel needles. Crystallises in broad needles, which do not deliquesce in the air. Is not formed on adding gold chloride to the solu- tion. Properties and- Reactions. — Saprine can be distilled unchanged in a current of steam. It has a faint odour of pyridine. It resembles cadaverine in most of its reactions, but forms with potassium bismuth iodide an amorphous instead of, like cadaverine, a crystalline precipitate. The pure base gives an intense blue GUANIDINES — PYKIDINE. 307 coloration with ferric chloride and potassium ferricyanide. It is physiologically inactive. The base Gerontine has the same composition as saprine. It is a leucomaine found in the hepatic glands of a dog. III. — Triamines and Tetramines of the Fatty Acid Series. No ptomaines which can be classified under this head have, as yet, been described (Gautier). GUANIDINES. Various ptomaines with the constitution of guanidines have been described, such as methylguanidine, glycocyamidine and propyl- glycocyamine, but with the exception of methylguanidine they have only been found among the products of pathogenic bacteria, and not as putrefactive bases. METHYLGUANIDINE [CgH^Ng or NH : J was isolated by Brieger from putrefied horseflesh, and by Bocklisch from decomposed beef extract. It has also been found in pure cultivations of various bacteria, such as those of mouse septicsemia. Properties. — The free base is crystalline, deliquescent and very alkaline. Treated with potassium hydroxide, it gives off" ammonia and methylamine. The hydrochloride [CgH^Ng.HCl] is insoluble in alcohol. The platinochloride [(C2H.^NgHCl)2.PtClJ forms rhombic crystals, which only dissolve with difficulty in water and alcohol, but are readily soluble in ether. The picrate is a resin-like substance, which is only sparingly soluble. Methylguanidine is very poisonous, and, on injection, produces muscular trembling, convulsions, dilation of the pupil of the eye, paralysis and death. AROMATIC PTOMAINES NOT CONTAINING OXYGEN. I. — Aromatic Monamines. PYRIDINE [CgHgN, or N This has been found among the decomposition products of proteids. It is a colourless liquid with a characteristic odour. 308 FLESH FOODS. It boils at about 116° C., and is miscible with water. It forms a pale blue precipitate with copper sulphate, which dissolves in an excess of the base. COLLIDINE or TRIMETHYLPYRIDINE (1) [CgHjiN or (1)] w’as separated by CEchsner and Coninck from putrid cuttle-fish. It is a yellow liquid with an acrid odour. It is slightly soluble iu water, and readily soluble in alcohol, ether and acetone. Its density is 0'986, and its boiling-point 168° C. The hydrochloride is crystalline, deliquescent, and very soluble. The platinochloride [(CgIIijN.HCl)2.PtCl4] forms red crystals, which are readily soluble in hot water. It is very poisonous. Nencki extracted from putrefied gelatin, a base with the same composition. PARVOLINE [CgHigN]. This poisonous pyridine base was discovered by Gautier and ^Itard in horseflesh which had been exposed for several months in hot weather. It is an oily amber-coloured substance, boiling above 200° C. It is slightly soluble in water, and very soluble in alcohol, ether and chloroform. On exposure to the air it turns brown. The platinochloride is precipitated as a crystalline mass, which turns brown on exposure to light and air. It does not dissolve readily. CORINDINE [C40H15N]. A base with this chemical composition was isolated by CEchsner, together with collidine from putrefied cuttlefish. It is a yellow^ somewhat viscous liquid, which boils at about 230° C., and has a disagreeable odour. It is soluble in alcohol, ether, and acetone, but only slightly soluble in water. On exposure to the air it becomes a resinous mass. The hydrochloride forms deliquescent needle-shaped crystals, which are very soluble. The platinochloride is a reddish powder, insoluble in water. Corindine is poisonous, causing paralysis on injection. DIHYDROCOLLIDINE [CgHigN]. This base was discovered by Gautier and Etard in 1881 in putrefied meat and fish, where it was accompanied by some of the AROMATIC PTOMAINES — DIAMINES. 309 pyridine bases mentioned above. It is a nearly colourless, slightly oily liquid with a penetrating odour. It attracts carbon dioxide from the air, forming a crystalline carbonate. It boils at about 208° C., and has a density of 1'0296 at 0° C. The hydrochloride crystallises in fine needles, which are very soluble in alcohol and ether. The platinochloride forms pale yellow, curved crystals, which are not easily soluble. On injection this ptomaine produces stupor, muscular paralysis, convulsions and death. DIHYDEOLUTIDINE [C^HnF]. This was found by Gautier and Margues in cod-liver oil. It is a colourless, oily liquid, strongly alkaline, and with a strong but not unpleasant odour. It absorbs carbon dioxide from the air. It boils at 199° C., and is slightly soluble in water. The hydrochloride is crystalline, and very soluble, but not deli- quescent. It is partially dissociated at 100° C. The platinochloride crystallises in yellow plates, and occasionally in fine needles. This ptomaine is very poisonous, producing, on injection, mus- cular trembling, partial paralysis, and asphyxia. BASE [C32H31N]. A ptomaine corresponding in composition with this formula was extracted by Delezinier from putrefied flesh. It is an oily, nearly colourless liquid, readily oxidised on exposure to the atmosphere. It resembles the alkaloid veratrine in its physiological effects. II. — Aromatic Diamines. MERLUSmE [CgHiaNa]. Found by Gautier in cod’s liver and in the water in which it had been kept. It is an oily, alkaline liquid, somewhat-soluble in water and very soluble in ether. It forms a crystalline acetate and platinochloride. III. — Aromatic Triamines. MORRHUINE rC,9H,-No] and HOMO-MORRHUINE These bases were found by Gautier in the part of the bases of cod-liver oil which were soluble in ether. 310 FLESH FOODS. Morrhuine is a viscous yellow oil, with a sweet odour and alkaline reaction. It precipitates copper from the solutions of its salts, but tlie precipitate does not dissolve on adding an excess of the base. The hydrochloride, which is very deliquescent, crystallises in stellate groups. ^ The platino-chloride forms microscopic needles. Homo-morrhuine closely resembles morrhuine in its properties. It is a viscous base of a yelloAv colour, and forms well-defined crystalline salts. The platinochloride [(C2oHo9N3HCl)2.PtCU is a yellow salt readily soluble in hot water. According to Gautier these two bases constitute more than a third of the total bases of cod-liver oil. They are but little, if at all, poisonous, but have marked diuretic and stimulating properties, and Gautier considers that part of the physiological action of cod-liver oil is to be attributed to their presence. IV. — Aromatic Tetramines. KICOMORRHUINE [CgoHsgNJ, Gautier found this base accompanying morrhuine and homo-mor- rhuine in cod liver which had been exposed to ‘ fermentation ’ before the extraction of the oil. It has the same percentage composition as nicotine Cj9Hj^N2, but from the composition of its platino- chloride Gaiitier doubled the formula. Properties. — It is a viscous oil with a faint odour of tobacco. It is slightly soluble in water, and has a density of about 1. Its hydrochloride crystallises in nacreous plates, which are very soluble in water, but not very deliquescent. The platinochloride [C2oH28N4.2HCl.PtClJ forms a flocculent brick-red precipitate insoluble in water. This ptomaine is somewhat poisonous. ASELLINE This is another base isolated by Gautier from cod-liver oil. On separating the basic substances of this oil by distillation, a brown residue is obtained, from which the morrhuines and nico- morrhuine can be extracted with ether. The insoluble portion contains a large proportion of a base with the above formula. Properties and Beactions. — The free base is an amorphous, greyish mass emitting an aromatic odour on warming. Its density is about 1 ’05. It is slightly soluble in water and ether, very soluble in alcohol. It combines with acids to form crystalline salts. ASELLINE— SCOMBRINE— NEURINE. 311 Its reactions may Sulphuric acid, . • Hydrochloric acid, Gold chloride, . . • Mercuric chloride, Flalimim chloride. be summarised thus : — Rose coloration, changing to brown. Small crystals arranged m an X-form. Gives a salt which is decomposed on treatment with boiling water. . , , .. White precipitate, soluble on heating, and deposit- ing as a crystalline mass on cooling. _ Yellow or orange precipitate, dissolving without flltftration on boiling. Gautier states that aselline composes about one-fifteenth of the total bases of cod-liver oil. Physiologically, it produces stupor and respiratory troubles in small doses, and convulsions and death when injected in larger quantity. SCOMBRINE was found by Gautier and Etard in the mother-liquid left on filter- ino- off hydrocollidine platinochloride, obtained during the putre- faction of fish, especially the mackerel. The platinochloride (Ci7H38N4.2HCl).PtCl4 crystalhses in yeUow needles. PTOMAINES CONTAINING OXYGEN OR SULPHUR. Gautier subdivides these into three groups— (i.) Neurinic bases ; (ii.) Aromatic bases containing oxygen ; (iii.) Amides or acid amides ; and (iv.) Carbopyridic acids. I. — Neurinic Bases. The ptomaines allied to neurine which have been found in the products of putrefaction are choline, muscarine, mytilotoxme (in poisonous mussels), a base with the composition C^Hj-lSOg, betaine, gadiuene, and mydatoxine. NEURINE [C5H13NO]. This base was discovered as a ptomaine by Brieger, who found it in the putrefaction products of flesh towards the fifth or sixth day, together with other bases, including neuridine and muscarine. It appears to be formed in putrefaction from choline [CgH^j^NOgJ by the loss of a molecule of water. Choline, itself, is a decomposi- tion product of lecithins, and is very unstable, being converted into neurine by heat or by the action of acids or alkalies. When the lecithins of the brain are acted upon by acids or bases, both choline and neurine are formed. Liebreich (1869) found that impure cerebral lecithin yielded neurine when heated for twenty- four hours with barium hydroxide. In composition it appears to be a hydroxide of trimethyl-vinyl- • /r^-crx at/CH = CH2 ammonium (CHglg ^ 312 FLESH FOODS. Properties and Reactions. — The free base is a syrupy liquid, with a very alkaline reaction, and giving off fumes on contact’ with hydrochloric acid. It is soluble in water, and is only removed in small proportion from the solution by ether, petroleum spirit, chloroform, and amyl alcohol. When concentrated solutions are boiled a small quantity of trimethylamine is evolved. Neurine chloride [C5H12NCI or C.HigNO + HCl-HoO] crystal- lises in fine needles, which are very hygroscopic. Brieger gives the following table of its reactions with different reagents : — l^sphoTmlyhdw acid, . . White crystalline precipitate, soluble in excess. Fhosphotungshc acid, . . Ml. Phosphoarditnonic acid, . Voluminous white precipitate. Potassium m^cury i^ide, . Voluminous yellowish- white precipitate. J otassium bis7niUh iodide, . Amorphous red precipitate. Potassium cadmium iodide. White precipitate. Iodine in potassium iodide. Amorphous brown precipitate. Tannin, ...... Voluminous dirty-white precipitate. Mercuric chloride, . . , White granular precipitate. Neurine is extremely poisonous, the symptoms varying somewhat with different animals. Speaking generally, it produces salivation, and ejaculation of other secretions. The pupils of the eyes are often contracted. In fatal doses there are sudden convulsions, and death rapidly ensues. Atropine has been found to be an active antidote, but neurine does not appear to be antidote for atropine. CHOLINE [C5H15NO2]. This base was first found by Strecker in bile, and also occurs as a normal constituent in the blood, muscles and glands of animals, and in extracts of various vegetable substances (e.f/., certain fungi). It is formed, together with neurine, in the ])roducts of the decomposition of lecithins, by acids or alkalies. Wurtz prepared it synthetically from trimethylamine and the mouochlorhydriu of glycol. According to Baeyer it is the hydroxide of trimethyl-oxyethyl-ammoniuni. Separation of Choline from Neurine. — Choline chloride is not precipitated by tannic acid, whilst neurine chloride is precipitated. On the other hand, phosphotungstic acid gives a precipitate with choline chloride, but not with neurine chloride. Separation of Choline from Neuridine. — On the addition of picric acid to the solution of the mixed chlorides, neuridine picrate is immediately precipitated, while choline picrate remains in solu- tion, and is only precipitated on concentrating the filtrate. CHOLINE — MUSCAEINE. 313 The aurochloride of neuridine is also much less soluble in water than that of choline. Properties and Reactions. — The chloride of choline forms very deliquescent needles, which are soluble in absolute alcohol. It gives the following reactions (Brieger) : — Fhosphotungstic acid, . . White precipitate, insoluble in water. Becomes crystalline on standing. Pliosphomohjldic acid, . Voluminous precipitate. Phosphoantimonic add, . White caseous precipitate. Potassium mercury iodide. Yellow crystalline precipitate. Potassium bismuth iodide, Ked amorphous precipitate. Iodine in potassium iodide. Brown granular precipitate. Mercuric chloride, . . . White granular precipitate. Tannin, Nil. Free choline is a syrupy liquid, very soluble in water. In a 2 per cent, solution it dissolves fibrin and coagulates albumin. When mixed with a large amount of water it is gradually trans- formed iuto neurine. Oxidising agents, such as dilute nitric acid, convert it into oxycholine or muscarine [CjH^^gNOg], betaine [CgHjjNOg], and oxyneurine [CgH^gNOg]. The platinochloride [((CHg)g)C2H^.OH(NCl2)2.PtCl4]is trimorphio in form, crystallising in plates, octahedra, or prisma. It invari- ably contains more or less water, which it does not lose at 110° C. It melts at 232° to 240° C. The aurochloride forms yellow needles, which dissolve with difficulty in water. The mercurochloride [CgHj^NOCl.OHgClg] is much less soluble thau the corresponding salts of putrescine and cadaverine, a pro- perty which can be used to separate choline from these and certain other ptomaines. The alkaline extract of the bases is slightly acidified with hydrochloric acid, the liquid filtered, and, after neutralisation of the excess of acid, evaporated in vacuo. The dry residue is taken up with alcohol, and an alcoholic solution of mercuric chloride added to the liquid. The precipitate, when recrystallised once or twice, is obtained in crystalline needles, which, when decomposed by hydrogen sulphide, give choline chloride. Choline resembles neurine in its physiological efiFects, but is much weaker in its action. Atropine is an antidote. MUSCARINE [CgH^gNOg] was found by Brieger associated with ethylidenediamine (?), neuridine, gadinene, and trimethylamine in putrid fish. It has been. 314 FLESH FOODS. isolated from poisonous mushrooms, and is formed artificially by the oxidation of choline. In composition it agrees with the formula (OH.)3rf<^OH(OH).CH,OH Drieger's Method of Separating Muscarine. — The alcoholic ex- tract of the putrefaction products is precipitated with mercuric chloride, in order to separate the choline and neurine. The filtrate is treated with hydrogen sulphide to remove the mercury, and filtered. The filtrate is concentrated, after neutralisation with sodium hydroxide, and the syrupy residue taken up in alcohol and mixed with an excess of platinum chloride. The platinochloride of neuridine crystallises out first, and is filtered off. On concentrating the filtrate, the platinochloride of ethyli- dene diamine (?) crystallises out, and on further evaporation, that of muscarine. This third precipitate, on treatment with hydrogen sulphide, gives the hydrochloride, which is converted into the sulphate by treatment with silver sulphate, and the latter, when decomposed with barium hydroxide, gives the free base. Properties and Reactions. — Muscarine forms colourless, deliques- cent crystals. It is extremely alkaline, and absorbs carbon dioxide from the air. The platinochloride [(C5Hi^N02Cl)2.PtCl4.2H20] crystallises in well-defined octahedra, which are sparingly soluble in water. The aurochloride forms needle-shaped crystals, which are nearly insoluble. Muscarine is very poisonous, producing, even in small doses, salivation, contraction of the pupils of the eyes, diarrhoea, convul- sions, and death. The action of atropine is antagonistic. BETAINE [C5H11NO2]. ’ This base is formed, together with muscarine, in the artificial oxidation of choline. It was found by Brieger in large quantity in both wholesome and poisonous mussels. It can be prepared synthetically by treating glycocoll with methyl iodide, dissolved in methyl alcohol, in the presence of potassium hydroxide ; also by the action of trimethylamine on chloracetic acid (CHg)3 i N -F CHgChCOOH = CHg : -F HCl. Properties and Reactions. — The free base [CgH^iNOg] forms brilliant crystals, which are deliquescent and dehydrated at 100° C. The hydrochloride crystallises in monoclinic plates, insoluble in absolute alcohol. The platinochloride [(C5HjjN02.HCl)2.PtCl^. -F 4II2O] is soluble in water. BETAINE — MYTILOTOXINE . 315 The mercurochloride is very soluble. The aurochloride dis- solves with diflBculty in cold water, but can be crystallised in plates from its solution in boiling water. Betaine causes a slow reduction in a solution of potassium ferri- cyanide with ferric chloride. Physiologically it appears to have no definite action on the system. HOMO-PIPERIMNIC ACID, OR S-AMIDO-VALERIC ACID [C.H„NOJ. This base, isomeric with betaine, was isolated by E. and H. Salkowski from the products of the putrefaction of meat fibrin. It crystallises in needles, which melt at 156° C., and dissolve readily in water, but only with difficulty in alcohol. It is not precipitated by copper acetate or by ammoniacal silver nitrate. According to Gabriel and Aschau it is identical with S-amido valeric acid synthetically prepared. The hydrochloride is crystal- line, and very soluble in water and concentrated alcohol. It is non-poisonous. {Cf. p. 321.) MYTILOTOXINE [CgHigNOs]. This base was isolated by Brieger from poisonous mussels in the following manner : — The flesh was extracted with boiling water containing a trace of hydrochloric acid. The extract was evaporated to a syrup, exhausted with alcohol, and the filtered solution treated with lead acetate to remove mucilaginous substances. The filtrate from this precipitate was evaporated to dryness, the residue taken up with alcohol, the lead re- moved by treatment with hydrogen sulphide, the alcohol evaporated, and the residue dissolved in water and decolorised with animal charcoal. The filtered solution was neutralised with sodium carbonate, then acidified with nitric acid and precipitated with phosphomolybdic acid. The precipitate was decomposed by heating it with neutral (normal) lead acetate, the liquid filtered, and after removal of the lead, and addition of hydrochloric acid, evapor- ated to dryness. The residue was taken up with absolute alcohol, which left a little betaine undissolved, and precipitated with alcoholic mercuric chloride. The mercurochloride was purified by recrystallisation from boiling water, and finally converted into mytilotoxine hydrochloride by treatment with hydrogen sulphide. Its composition is doubtful, but it is possibly a methyl deriva- tive of betaine. The hydrochloride crystallises in tetrahedra. The aurochloride melts at 182° C. With regard to the physiological properties of mytilotoxine, see under ‘Mussel Poisoning,’ p. 221. 316 FLESH FOODS. MYDATOXINE [CgHigNOa]. This base was isolated by Brieger from horseflesh which had been left to putrefy for nine to fifteen months. It was accom- panied by cadaverine and putrescine, and by a base with the fomiula C^Hj^NOg. Brieger' 8 Method of Isolating Mydatoxine. — The bases were pre- cipitated as mercurochlorides, and the precipitate crystallised from boiling water. The mercurochloride of cadaverine separated first, and was filtered off. The filtrate was treated with hydrogen sulphide to remove mercury, filtered and evaporated, and the residue taken up with absolute alcohol, which left undissolved the hydrochloride of putrescine. The alcohol was evaporated and the mydatoxine precipitated as aurochloride, which was converted into hydrochloride by means of hydrogen sulphide, and this, when left in contact with silver oxide, gave the free base. Properties and Reactions. — As thus obtained, mydatoxine is an alkaline, viscous liquid, which solidifies in plates on evaporation m vacuo. It is insoluble in alcohol and ether, and non-volatile. Its reactions are : — Hydrochloric acid, . . . Deliquescent salt. Platinum chloride, . . , Small lamellse, soluble in water. Melts about 193° C. Vettr^U^ide', \ '. \ } precipitates soluble in boiling water. Potassium ferrkyanide and ferric salts, Kapid reduction takes place. The relation between mydatoxine and mytilotoxine may be expressed as in the formulae : — (CH,).K oint of fats, 91. Jlerck’s peptone, 175, 199, 203. Mercuric chloride, precipitation of pro- teids by, 167, 171, 173, 205. iodide, i)recipitatiou of proteids by, 174. Merlusine, 309. Metals in canned meats, 116. precipitation of proteids by salts of, 1 65. Methtemoglobin, 38, 39. Methylamines, 300. 1 Methyl-gadinine, 317. Methj'l-glycocoll, 17. Methyl-guanidines, 9, 224, 307. Mettwm-st, 127. Micro-organisms, determination of the number of, in flesh, 267. Microscopical examination of flesh, 117, 142, 250, 257. Microtomes, 267. Miescher’s tubes, 228, 259. action of heat on, 229. i Millou’s proteid reaction, 161, 162. Mineral matter in blood, 42. I in bone, 31. in muscle, 21. iu muscle, determination of, 79. I Moisture iu muscle, abnormal, 79. I determination of, 79. Monamines, 223, 300. Morrhuamine, 319. Morrhuic acid, 322. Morrhuine, 309. ; Mucin, 24, 149, 153. j Mucoids, 153. I ilule’s flesh, 66, 135. I Murexide test for xanthine, 15. Muscarine, 223, 225, 313. Muscle, chemical composition of, 22. colouring matters of, 6, 7, 70. free acids of dead, 19. mineral constituents of, 21. non-uitrogenous organic con- stituents of, 7. ; proteid constituents of, 4. I reaction of, 19, 75, 76. structure of, 1. Muscle distomum, 261. Muscle plasma, 5. Muscle ray-fungus, 259, 296. Muscle trichina, 254 Muscular fibre, determination of, 82. Mussel, flesh of, 67, 68. poisoning by, 221, 315. Mutton, ‘ braxy,’ 63. characteristics of, 61. chops, 209. cooked, 208. digestibility of, 87. food value of, 88. Mutton fat, constants of, 54. stearic acid iu, 54. Mydaleine, 317. Mydatoxine, 224, 225, 316. Mydiue, 224, 318. Myogen, 5. fibrin, 5. INDEX. 331 Myohiematin, 7. Myoproteid, 6. Myosin, 5, 149. action of certain dyes on, 143. productsofthe proteolysis of, 181. Myosin-librin, 6. Mytilotoxine, 222, 315. Nematoda, 252. Neuridiiie, 17, 218, 222, 224, 305. Neurine, 218, 223, 225, 311. Neurinic bases, 311. leucomaines, 8. Nicomorrhuine, 310. Niebel’s method of estimating glycogen, 137. Nitre, action of, on hsemoglobin, 144, 145. as a flesh-colour preservative, 107, 145. Nitrogen, amide, estimation of, 82. methods of determining, 80. Nitrogenous constituents of meat extracts, 192, 193. Non-striated muscle, 1. Nucleins, 6, 80. composition of, 6, 149. Nucleo-albumin, 4. action of certain dyes on, 143. Nutrient units of flesh, 88. Nutritive value of commercial pep- tones, 189, 191. of meat extracts, 187. Odour of blood, 33. of flesh, influence of sex on, 63, 78. Oleic acid, characteristics of, 27. Farnsteiner’s method of separat- ing, 100. in pig’s fat, 56. Olein, 25, 27. Optical rotation of proteids, 163. Ossein, 31. Osseous tissue, composition of, 31. structure of, 29. Ostracion or trank-fish, 220. Ox, blood of the, 43. bones of the, 21, 32. composition of an, 49. Ox, cysticercus of the, 231, 233, 248. Ox-flesh, action of potassium hydrox- ide on, 134. characteristics of, 49. composition of, 47, 49, 50, 105. digestibility of, 50, 86. extractives from, 48. See ‘ Beef.’ Ox tallow, 50, Ox tongue, smoked. 111. Oxygen in blood, 42. Oxyhsemocyanin, 45, Oxyhffimoglobin, characteristicsof,34. composition of, 35, 149, crystals, 34. estimation of, 36. identification of, 35. separation of, 34. spectrum of, 36, 39. Oysters, composition of, 68, 210, 211. copper in, 68, 117. green, 68. hsemolymph of, 45, 68. liquid in, 67. pathogenic bacteria in, 296. phosphorus in, 68. Palmitic acid in pigs’ fat, 56, characteristics of, 27. Palmitin, 27. Pancreatic digestion, 86. action of, on proteids, 182. experiments with, 86. Pancreatic peptone-s, composition of, 199, 203. manufacture of, 190. Papayotin, proteid digestion by, 185. manufacture of commercial pep- tones by, 185, 198. Papayotin peptones, analyses of, 203. Paraglobulin (serum globulin j , 4 1 , 1 49 . Parasites, animal, action of cold upon, 249, 261. action of cooking upon, 211, 248. actionof putrefaction on, 249,263. detection of, in flesh, 250, 257. in flesh, 211, 227. influence of salting on, 263. influence of smoking on, 250, 263. thermal death points of, 211, 248, 261, 262. Paraxanthine, 16. Parvoline, 224, 308. Pate de foie gras, 118. Pathogenic bacteria in flesh, 279. Pathological ptomaines, 322. Pemmican, 104. Peptic digestion of proteids, 179. experiments, 86. peptones prepared by, 190. Peptones, action of dyes on, 143. action of formaldehyde on, 176, 199. characteristics of, 158. 332 INDEX. Peptones, composition of, 159, 181. compounds of, with hydrochloric acid, 160, estimation of, 173, 192, 195. flesh, analyses of, 199, 203, 205. flesh, prepared by papayotin, 190. flesh, prepared by pepsin, 190. flesh, prepared by superheated steam, 189. flesh, prepared by trypsin, 190, from gelatin, 159, 162. injection of, into the blood, 191. in meat extracts, 196, 201, 206. Kemmerich’s, 189, 198, 203. Koch’s, 189, 203. physiological value of, 190. precipitation of, by bromine, 168. precipitation of, by phospho- tuugstic acid, 167. precipitation of, by uranium acetate, 173. Witte’s, 205. See ‘ Anti-’ and ‘ Hemi-pep- tones.’ Perch, flesh of the, 65. Periodic law, precipitation of proteids in relation to, 165. Pheuyl-amido-propionic acid, 321. Phospho-carnic acid, 6, 82. Phosphomolybdic acid as a proteid precipitant, 174. Phosphorescent flesh, bacilli of, 273. occurrence of, 272. Phosphoric acid, determination of, 80. Phosphorus, in blood, 43. in fish, 21. • in flesh, 22, 80. in oysters, 68. in lecithins, 21, 80. in nucleins, 21, 80. poisoning, effect on flesh, 217. Phosphotungstic acid as a proteid precipitant, 167. method of preparing, 168. Physiological experiments in diges- tion, 87. Pickling fluid, composition of, 109. of flesh, 108. Picric acid, precipitation of proteids by, 174. Piestocystis in the crow, 244. Pig, composition of a, 49. Pigeon, fat of the, 63. flesh of the, 60, 61. Pigments in flesh, 6, 7, 70, 71. Pig’s blood, haemoglobin of, 144. Pig’s fat, characteristics of, 55. constants of, 57. Pig’s flesh, 21, 47, 55. See ' Pork. ’ Pike, flesh of the, 21, 65. Plasma, blood-, 40, 42. muscle-, 4, 5. Pleuro-pneumonia, flesh of animals infected with, 294. of cattle, micro-organisms of, 294. Poisonous canned meat, 116. fish, 219. flesh, 216. mussels, 221. sausages, 225. See ‘ Ptomaines.’ Poisons, effect of, on flesh, 216. Polony sausages, 128. Pork, characteristics of, 54. composition of, 55. digestibility of, 55. food value of, 89. glycogen in, 138, 139. influence of pig’s food on, 55. mineral constituents of, 21. sausages, 128. Potassium hydroxide, action of, on muscle, 134. Potted meats, composition of, 118. Pouchet’s bases, 319. ptomaine extraction method, 298. Preservation of flesh, by antiseptics, 118. by cold, 102. by drying, 104. by heat sterilisation, 112. by salting, 107. by smoking, 110. Primary proteo.ses, 155, 179. Pro-peptones, 155, 203. Propjrlamines, 109, 223, 301. Proteids, action of formaldehyde on, 175, 199. classification of, 150. coagulation of, 162, 163. colour reactions of, 160. compounds of, with hydrochloric acid, 160. decomposition by bacteria, 185. decomposition by papayotin, 185, 190. decomposition by pepsin, 179,190. decomposition by sulphuric acid, 176. decomposition by superheated steam, 177, 189. INDEX. 333 Proteids, decomposition by trypsin, 182, 190. optical rotation of, 163. precipitation of, by alcohol, 164, 199. precipitation by copper hydrox- ide, 170. precipitation by halogens, 168. precipitation by metallic salts, 166. precipitation by phosphotung- stic acid, 167. precipitation by ‘ salting out, '164. precipitation by tannin, 174. Protein-chromogen, 184. Proteolysis, products of, 181. Proteoses, characteristics of, 164. composition of, 149, 181. deutero-, 165, 156, 181. primary, 155, 181. Proto-albumoses, 156, 181. Protozoa, 227. Pseudo-xanthine, 14. Psorosperm saccules, 228. Ptomaines, classification of, 223. composition of, 223. . extraction of, 298. flesh of animals poisoned by, 278. known also as leucomaines, 218. pathological, 322. separation of, 298. symptoms of poisoning by, 224. Purple flesh, 71. Putrefaction, bacteria of, 27 4. bacterial products of, 277. Eber’s test for, 75. influence of, on animal parasites, 249, 263. ptomainesformedduringthe, 223. reaction of flesh during, 19, 74, 75. Putrescine, characteristics of, 303. physiological effects of, 224. separation of, 303. ‘ Putrid intoxication,’ 278. Pyaemia, 279. Pyogenic bacteria in flesh, 279. Pyridine, 307. Quarter-evil, bacillus of, 288. flesh of infected animals, 289. Quick-salting process, Eckart’s, 107. Rabbit, bones of the, 31. coccideal disease of the, 229. fat of, 63. flesh of, 60. Rabbit, food value of. 89. mineral matter in flesh of, 21. Rabbit septicaemia, 281. Rabies, destruction of virus of, by heat, 213, 285. flesh ofanimalsinfectedwith,285. virus of, 285. Ram, flesh of the, 33. Ray-fungus, muscle, 259, 296. Reaction to litmus, of blood, 33. of canned meat, 116. of caviar, 110. of muscle, 19, 75, 76. Red corpuscles of blood, 33. sausage, 125. Redness of flesh, abnormal, 71. Reichert value, determination of, 94. Rigor mortis, 4, 19, 209. Rinderpest, 294. flesh of infected animals, 295. ‘ Ripening ’ of game, 62. Roasting of flesh, 208. Roe of fish, 18, 109. poisonous, 218, 220. Rbntgen rays, trichinae detection by, 258. ‘ Roseline,’ 72. Rose’s method of separating fatty acids, 96. Rust, detection of blood in presence of, 44. Saffron, coloration of flesh by, 71. Safranin, detection of, in sausages, 143. action of, on flesh proteids, 143. Salamiwurst, 126. Salicylic acid, detection of, 122. flesh preserved with, 76, 122. Salmon, canned, 113. colouring matter in flesh of, 7, 64, 117. cooked, 210, 211. digestibility of, 87. flesh of, 65. ova of, 117. Salmon, potted, 118. smoked. 111. Salt in meat extracts, 188. Salt fish, 108. Salt meat, 108. Salting, action of, on animal parasites, 263. action of, on bacteria, 108. influence of, on the flesh, 108. methods of, 107. 334 INDEX. Saponification value, determination of, 93. Saprasmia, 265, 278. Saprine, 223, 224, 306. Saprophytic bacteria, 274, 279. Sarcine, 14. Sarcolactic acid, 20, 103. Sarcolemma, 2, 3, 5. Sarcoplasm, 4, 5. Sarcosine, 17. Sarcous elements, 4. Sardines, canned, 114. cooked, 210, 211. oil of, 66. red coloration of, 115. Saucisses, 128. Saucissons, 128. Sausages, acidity of, 133. American, trichinse in, 264. analyses of, 127, 128. animal parasites in, 249, 263, 264. artificial coloration of, 142. bacteria in, 269, 272, 278. blood, 125, 127. composition of, 125, 128. cooking of, 262. English, 126, 128. examination of, 129-146. French, 128. German, 125, 127. pistle in, 133. horse flesh in, 133. liver, 125, 127. phosphorescent, 272. poisoning, 225, 278, preservatives in, 118, 122. specific giavity of, 130. starch in, 130. temperatures in cooking, 214. water in, 129. Sre ' Beef,’ ‘Pork.’ Saveloy.s, 128. Scarlet flesh, 71. Scherer’s test for inosite, 20. Schjeniing’s analyses ofmeat extracts, 174, 205. proteids, separation method, 171. Schjerning’s ob.servations on the precipitation of proteids, 165. Schrbtter’s albumose, 157. Scombrine, 311, Scyllite, 21. Section cutting, 267. Septicaemia, flesh of animals infected with, 214, 220. Septicaemia, micro-organisms of, 280. See ‘ Rabbit.’ Seram-albumin, 41, 149. Serum-globulin, 41. Serum of cal Ps blood , proteid s in 174 ‘Blood. ■ Sex, influence of, on the flesh of animals, 49, 51, 54, 77, 78. Shark oil, constants of, 66. Sheep, bones of, 31, composition of a, 49. cysticercus of, 242. fat of, 53. flesh of, 47, 51, 53. See ‘ Jlutton.’ Sheep-pox, 289. Shell-fish, bacteria in, 296. blood of, 45. digestibility of, 87. flesh of, 63. mineral matter in flesh of, 21. Skate oil, constants of, 66. Smoked flesh, bacteria in, 270. composition of. 111. Smoking, action of, on animal parasites, 250, 263. action of, on bacteria, 110. influence of, on flesh. 111. methods of, 110. Snails, flesh of, 68. poisonous, 216. Sodium chloride, precipitation of proteids by, 165. Sodium salicylate, extraction of colour with, 145. Sole, flesh of, cooked, 210, 211. Somatose, 171, 189. Soup, 209. Specific gravity of connective tissue, 24. of blood, 33. of fat, 27. of sausages, 130. Spectra of haemoglobin and its ! derivatives, 39. I Spirilla, 266, 276. I Squirrel, haemoglobin crystals from the blood of, 35. Stag, fat of, 63. ‘ Staggers ’ in sheep, 241. Staining tissues, methods of, 267. Stannous chloride, precipitation of proteids by, 170, 172, 205. Staphylococci, 212, 213,266,270,279. Starch, determination of, in sausages, 130. INDEX. 335 steam, action of superheated, on flesh, 177. action of, on proteids, 178, manufacture of peptones by, 189. j Stearic acid, characteristics of, 27. determination of, 99. in animal fats, 26, 54, 56, 58. Stearin, 25, 27. Sterilisation of flesh, 112. public, 214. Stock-fish, dried, 107. Streptococci, 212, 266, 279. Striated muscular fibre, 1, 4. Stroma substance, 7. Sturgeon, roe of, N«« ‘Caviar.’ Sulphites, action of, on flesh, 76, 121. detection of, 121. Sulphur-compounds, Eber’s test, 73. formed in ‘ heating ’ of game, 62. formed in ripening of game, 62. Sulphur in flesh, 21. determination of, 80. Sulphuric acid, action of, on proteids, 176. Twitchell’s method of separating liquid fatty acids with, 99. Sulphurous acid as a flesh preserva- tive, 76, 120. Susotoxine, 282. Swine, cysticercus of, 235. Swine erysipelas, 73, 283. Swine fever, 281. See ‘ Pig ’ and ‘ Pork.’ Syntonin, 6, 160, 156, 168, absorption of, in the .system, 191. action of certain dyes on, 143. characteristics of, 152, 164. determination of, 169, 192. in meat extracts, 191, 192. T.hkia acanthotrias, 231, 238. coenurus, 231, 240, crassiceps, 244. crassicollis, 241, cucumerina, 231, 244. echinococcus, 231, 242. flavo-punctata, 244. londcollis, 244. madagascariensis, 244. marginata, 231, 238. mediocanellata, 231, 232. nana, 244. perfoliata, 244. saginata, 231, 232. serrata, 231, 1239. solium, 231, 234. Tfenia tenella, 231, 241. TseniadfE, 230, 244. and their related cysticerci, 231. thermal death points of, 248. Tallow. See ‘ Ox.’ Tannin, Almen’s reagent, 174. precipitation of proteids by, 83, 167, 174. Tapeworms, cystic, 232. hosts of, 231. ordinary, 244, See ‘Tfenia’ and ‘Toeniadae,’ Tassajo, Came, 104. Taurine, 18. Tetanus, bacillus of, 284. bacillus of, thermal death point, 212, flesh of infected animals, 285. virus of, influence of heat on, 213, 285. Thrombin or fibrin ferment, 41. Tin in canned meats, 116. Tin chloride, precipitation of pro- teids by, 170, 172, 205. Tongue, canned, 113. potted, 118. smoked, 111, toughness of, 78. Toughness of flesh, determination of, 77. Toxalbumoses, 191, 218. Toxigenes, 225. Toxines, bacterial, 213, 278. bacterial, action of heat on, 213, 226. in fish, 64, 221, 222. in flesh, 217, 218, 278. Trematoda, 251. Trichina spiralis, intestinal, 252. muscle, 254. Trichinae, bodies liable to be mistaken for, 258. detection of, in flesh, 258. influence of cold on, 261, Trichinae, influence of cooking on, 211, 262. influence of heat on, 262. influence of putrefaction on, 263, influence of salting on, 263. influence of smoking on, ,263. inspection of meat for, 257. number of, in infected flesh, 257. position of, in flesh, 260. Trichinosis, occurrence of, 263. prevention of, 262. symptoms of, 256, 336 INDEX, Trichloracetic acid as a proteid pre- cipitant, 155. Triethylamine, 223, 301. Trimethylamine, 109, 223, 300. Trimethylenediamine, 302. 'I’rout, digestibility of, 87. Trypsin, action of, on proteids, 182. digestion of gelatin by, 1 85. manufacture of peptones by, 190. Tryptic digestion, artificial, 86. Tryptone, 175. Tryptophan (protein-chromogen), 184. Tuberculin test, 292. Tuberculosis, Eber’s test for, 74. fle.sh of infected animals, 21 3, 291. in cold-blooded animals, 294. occurrence of, 289, 293. symptoms of, 289. toxine of, action of heat on, 213. Tuberculosis, bacillus of, 289. action of gastric juice on, 290. influence of cooking on, 290. influence of putrefaction on, 291. influence of salting on, 290. influence of smoking on, 290. thermal death point of, 212, 290. Turbot, composition of, 210, 211. Turkey, bones of the, 31, 32. fat of the, 63. Tyrosamines, 224, 318. Tyrosine as. a digestion product, 183. as a ptomaine, 321. characteristics of, 18. deposits in ham, 260. in flesh, 18. separation of, 184. Tyrotoxine or tyrotoxicon, 320. Uranium acetate, precipitation of proteids by, 159, 170, 171, 173. Urase, 161. Urine, extravasation of, into muscnlar tissue, 79. kreatinine in, 9. ptomaines in, 322. removal of peptones by, 191. Valentine’s meat juice, 197. V an Ermengem’s bacillus of sausage poisoning, 226, 278. Veal, characteristics of, 61. composition of, 47, 51. extractives from, 48. immature, 51. Nee ‘Calf.’ : Venison, composition of, 60, 61. fat, constants of, 63. See ' Game.’ I Violet coloration of flesh, 71, 272. I ‘ Vitalia ’ meat juice, 197. ' Vitellins, 150, 152, 167. : Water in flesh, 21. abnormal proportion of, 79. I absorption of, by flesh, 142. j determination of, 79. I in meat extracts, 187, 193, 197. in sausages, 120. i Weigert’s method of staining, 267. White flesh, 70. ; White of egg, 148, 149, 152, 153, 169. I Wild animals, fat of, 60, 63. flesh of, 60. Wild cat, fat of, 61. duck, fat of, 63. goose, fat of, 63. rabbit, fat of, 63. See ‘ Game.’ Wildseuche, 281. Witte’s peptone, 171, 174, 205. Wyeth’s meat juice, 197. Wtirste, 125, 127. Xanthio bases, 8, 11. testa for, 11. Xanthine, 15. See ‘ Hetero-,’ ‘ Para-,’ and ; ‘ Pseudo-xanthine.’ Xantho-kreatinine, 10. : Xantho-proteic reaction, 161. I Xantosis, 71. ! Yellow flesh, 70. j Yolk of egg, 18, 162. Zein, 160. . Zinc sulphate as a proteid precipitant, 164, 192, 198. PRIKTED BY NEILL AND COMPANY, LIMITED, EDINBURGH.