37 



SUCHOSAURUS. 



SUID.-E. 



939 



It includes those families which are remarkable for the succulent 

 character of their leaves, as Saxifragacecs, Crussulaccce, Ficoidacece, Ac. 



SUCHOSA'URUS, a genus of Fossil Saurians of the Wealden 

 Formation of Tilgate. 



SUCKING-FISH. [DISCOBOLI; ECHISEIS.] 



SUCTORIA. [PCLEX.] 



SUCTORIA. [ANNELIDA.] 



SUCTORIAL CRUSTACEANS. [SIPHOXOSTOMATA.] 



SUGAR is a sweet soluble crystallisable substance found very 

 generally in plants. It differs from the other assimilable secretions of 

 plants in its solubility, its sweet taste, and the readiness with which 

 it enters into fermentation. Chemists have detected different kinds 

 of this substance. Thus there is Cane-Sugar, Grape-Sugar, Eucalyptus- 

 Sugar, Milk-Sugar, &c. There are other sweet secretions of plants as 

 Mannite and Glycyrrhizin, which seem to be modifications of some 

 common form. 



The physiological action of Sugar deems to be indicated by its 

 ready solubility, a property which renders it easily conveyable from 

 one part of the plant to another. 



Sugar i* found under all circumstances in some plants, but in the 

 great m?s of the vegetable kingdom it presents itself at particular 

 seasons. It is found very generally in the seed during germination. 

 It appears that the starch of the albumen of the seed is converted 

 first into dextrine and then into sugar, whilst the embryo is growing. 

 Here it seems a provision for assisting the growth of the tender tissue 

 of the germ. In this stage it is obtained for the purposes of fermen- 

 tation, as in the brewing of beer, where germinating barley is con- 

 verted into malt for the sake of the sugar. 



Sugar is frequently found in considerable quantities in the sap of 

 trees previous to their budding. It is found in sufficient quantities 

 in the sap of Acer laccharinum, to be separated for dietetical purposes 

 in North America. The Common Birch (Betuln alba) contains so 

 large a quantity of sugar in its nap that it is employed in the north 

 of England and Scotland for making an effervescing wine in consider- 

 able repute. Many other trees yield sugar in their sap. 



The roots of many plants contain sugar. The Beet-Root is exten- 

 sively cultivated in Germany and France for the purpose of yielding 

 sugar. The Turnip, the Carrot, and the Parsnip, are familiar instances 

 of roots which contain sugar, and which owe their principal dietetical 

 value to this circumstance. The roots of many plants eaten by 

 animals contain sugar, and are probably sought after on this 

 account. Most of the plants belonging to the natural family of Grasses 

 contain sugar. The Saccharum officinarum is the principal source of the 

 sugar that is used dietetically in Great Britain. It is contained in its 

 tissues at almost all seasons of its growth, but it is present in espe- 

 cially large quantities previous to flowering ; it is at this stage that 

 the sap is employed for the manufacture of sugar. The Indian Corn 

 (Zea Mays) yields a sufficient quantity of sugar to render it a profitable 

 source of manufacture in the United States of America. Barley, oats, 

 wheat, rye, and rice, all contain sugar in their stems, and might be cul- 

 tivated for this purpose were they not more valuable as producers of 

 grain. The dietetical value of grasses on which cattle and horses are 

 fed depends in a great measure on the quantity of sugar they contain. 



Many of the Palm Tribe yield sugar in their sap. The Caryota ureni, 

 Cocoa nucifera, and species of Sayui, are used in tropical countries for 

 obtaining sugar. 



Another source of sugar in the vegetable kingdom is the Fruit. 

 Nearly all the fruits of plants eaten by man contain sugar. Such are 

 the grape, the orange, the pine-apple, pear, and numerous others. 

 The different species of sugar have .the following composition : 



1. Milk-Sugar .... C M H 18 19 + 5 H 



2. Cane-Sugar . . . . C xl H g 0, + 2 H 



3. Grape-Sugar . . . . C,, H,, 0,., -I- 2 H O 



4. Encalyptus-Sugar . . . C,, H la O la + 9 H 

 Milk-Sugar is an integral constituent of the milk of the Mammalia, 



and has very rarely been met with anywhere else. It has been said to 

 have been detected in eggs during the process of incubation ; but this 

 observation requires to be confirmed. Cane-Sugar ia the most closely 

 related to starch and dextrine, differing from them merely by one 

 equivalent of water. It is not by any means so widely distributed as 

 Orape-Sngar, being found in very few plants besides the sugar-cane, 

 beet, and maple. Grape-Sugar is identical with the sugar in honey 

 and in diabetic urine, and with the Glucose or fruit sugar of the French 

 chemists. The uncryatallisable sugar which is obtained during the 

 decomposition of many plants, and which is yielded by starch acted 

 on by diastole or sulphuric acid, has the same composition as Grape- 

 Sugar. Cane-Sugar is not fermentable. The only fermentable form 

 of sugar ia Grape-Sugar ; and in all cages where alcohol is formed, the 

 substances employed must pass into the form of Grape-Sugar. 



Eucalyptus-Sugar is a species of manna produced in Van Dicmeu's 

 Land by various species of Eucalyptvu. Whether it is the natural sap 

 spontaneously escaping, or whether it is the sap extracted by the 

 locust and afterwards excreted, is uncertain. Its properties have been 

 carefully examined by Professor Johnstone. 



There i* obviously an intimate connection between these different 

 kinds of sugar, as well as between cellulose, starch, dextrine, and gum. 

 They all contain carbon, in combination with the elements of water. 



As they all contain C I2 or a multiple of it, they are produced from 

 each other by a simple change depending on catalytic force. 



If sulphuric acid is allowed to act on gelatin, a species of sugar 

 containing nitrogen, and termed Glycicoll or gelatiu sugar, is formed. 

 Its formula is C, H 9 N 2 0, ; and it is worthy of remark, that if 

 from two of its equivalents we deduct one equivalent of cane-sugar, 

 we obtain the elements of two equivalents of urea, or 



2 (C. H 9 N s 0,) - C ia H 10 10 = 3 (C, H 4 N s 2 ). 

 This relation leads to the belief that sugar is a component part of 

 the gelatinous tissues, and when separated from them it may be 

 presumed to discharge the same functions as when either cane- or 

 grape-sugar is supplied with the food. In other words, there exists 

 in the substances yielding gelatin a primary matter which exists 

 also in cane-sugar. If then substances or tissues containing gelatin 

 are employed in effecting the metamorphosis continually occurring 

 in the animal body, this primary matter may serve the same purpose 

 as cane-sugar when supplied to feed the body. On these grounds 

 Mulder considers that gelatin-sugar should be classed amongst the 

 nourishing substances. If gelatin be formed in the animal body, 

 then sugar, either derived directly from the food or produced from 

 starch iu the alimentary canal, may be used for this purpose. 



It is not known in what part of the plant sugar is formed. Mr. 

 Knight states that birch sap contains more sugar the farther from the 

 root it is collected ; this seems to prove that the sap, which probably 

 contains much dextrine, is changed into sugar as it passes through the 

 cell-walls. When sugar accumulates in certain parts of a plant, it 

 almost always remains in solution ; it is however found crystallised iu 

 some few instances, as iu the nectary of Fritillaria imperialis. 



Closely allied in its chemical composition to sugar is a peculiar 

 substance to which the term Mucilage is given. Although iusoluble 

 iu water, it assumes the appearace of a mucilaginous mass when im- 

 mersed in that fluid. It sometimes accumulates largely in certain 

 parts of plants, as in the perisperm of quince-seed, lint-seed, &c. ; it is 

 the chief constituent of the gums tragacanth and Bassora, and is 

 abundant in various roots, as for instance the mallows. According to 

 Mulder's analysis it must be represented by the formula C 24 H 19 19 . 

 It has been shown by Schmidt that mucilage when digested with 

 dilute sulphuric acid is converted into sugar. Hence it supplies a link 

 to the following series of analogous substances : 



Grape-Sugar and Fruit-Sugar C M H 2t 0.,, 



Cellulose and Soluble Inuliu C 24 H. 21 21 



Starch, Dextrin, Gum, Insoluble Inulin, and Lichen- 

 Starch C a4 H_ M 



Mucilage, Milk-Sugar, and Eucalyptus-Sugar . . C.,, H 19 O 19 



Cane-Sugar . , C^ H 18 19 



In its physical characters, the product of the mucous membrane of 

 the animal body resembles vegetable mucilage. Owing to their insolu- 

 bility in water, both these substances serve to cover denuded parts of 

 animals, and thus they are both suited to lessen or prevent the 

 influence of acrid matters on the tender parts of the animal frame. 

 It is for this reason that the mucilage of salep, tragacanth, &c., may 

 be made, in certain diseased conditions, to supply temporarily the 

 want of animal mucus. In chemical composition they are perfectly 

 distinct, as animal mucus contains nitrogen. The mucus of tha 

 animal body seems however to differ according to the organs by which 

 it is produced. (Day's edition of Simon's 'Animal Chemistry,' vol. ii. 

 p. 78, note.) 



SUGAR-CANE. [SACCHARUM.] 

 SUGAH-SQUIRREL. [MABSOPIATA.] 



SU'ID^E, a family of Pachydermatous Animals, including the various 

 forms of Swine. 



The Swine have on each foot two large principal toes shod with 

 stout hoofs, and two lateral toes which are much shorter and hardly 

 touch the earth. The incisor teeth are variable in number, but the 

 lower incisors are all levelled forwards. The canines are projected 

 from the mouth and recurved upwards. The muzzle is terminated by 

 a truncated snout fitted for turning up the ground, and the stomach is 

 but little divided. 



Cuvier remarks that the skull of a hog is nearly a quadrangular 

 pyramid, the palatiuc surface of which is almost perpendicular to the 

 base, represented by the occiput. The nasal bones occupy the upper 

 part of the muzzle ; their base is slightly widened ; the other extremity 

 advances a little pointedly above the nasal aperture. The intermaxil- 

 larieg ascend rather obliquely to one-third of the length of the nasal 

 bones, and carry at their extremity the peculiar bone which supports 

 the snout. The orbit is round, and well defined (cemd) by an advance 

 of the frontal and the two post-orbital apophyses ; the portion formed 

 by the frontal especially is well marked. Between the two it is nearly 

 the sixth of a circle, not closed. The frontals descend in front of the 

 orbit more than a fourth of the length of the muzzle before they 

 encounter the nasal bones. The lachrymal bone occupies a rather 

 large rhomboidal space upon the cheek. The two lachrymal holes are 

 pierced, the upper one on the border itself, the other a little in front 

 of the border of the orbit In the orbit, the lachrymal descends to 

 the upper border of the vault of the sub-orbital canal. The jugal bone 

 is articulated to the whole width of the lachrymal bone. It is elevated, 

 and the suture with the temporal bone behind the post-orbital 



