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in diameter, subcompressed, rounded or polygonal in shape; which escape by rupture of the follicle. These cells slightly increase and become filled by opaque granules, fig. 385, resembling the granular contents of the free secretion, which granules appear to be liberated by the solution and disappearance of the cell-wall. The spaces containing both follicles and cells are circumscribed by productions of a basilemma defining the ultimate lobules or 'acini' of the pancreas: in one of these, fig. 386, may be seen a group of follicles containing two results of formifaction, called 'stages of selective or epithelial cells.'1

The following are among the later and more exact analyses of the pancreatic secretion from a carnivorous and a herbivorous species of mammal :

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Frerichs' water-extract' and Schmidt's 'organic matter' signify a substance resembling albumen and casein, but not identical with ptyalin. The pancreatic secretion differs from the salivary in containing more than double the amount of solid residuum, in which albumen and casein are abundant; while they exist in very small quantity in saliva. Saliva is neutral, or contains a little alkaline carbonate: the pancreatic secretion contains a little free acid. Saliva contains sulpho-cyanide of potassium; in the pancreatic fluid there is none.

This fluid completes the process of converting amylaceous

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In using the terms 'cell' and 'nucleate cell' I would not be understood as implying that such are progeny of previous cells, owing their origin to a genetic process inherited from one primordial form into which life was first breathed (ccxIII". p. 484).' The cell is one of the forms in which proteine matter in solution may be aggregated, with limitation of size and definition of shape; such forms differing from crystals in being rounded instead of angular, as shown in the instructive experiments of Rainey (CCIX". p. 9.) Accordingly, to express this act, I use, instead of 'crystallise,' the word 'formify,' for crystallisation formifaction,' for crystallising formifying' such terms imply, simply, the fact of the assumption of the forms called 'granule,' 'corpuscle,' monad,' 'globule,' 'disc,' 'cell,' 'nucleus,' 'nucleate cell,' &c. Formified particles' cling, like crystals, to the free surface of the cavity containing the solution, and are then termed epithelial cells' such surface seems favourable to the initiation of the formifying process: but a large proportion of the results of such process is manifested in the free state, like the fine crystals that follow concussion of water cooled gradually and quietly below the freezing point.

2 CLXII".

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3 CLXIII".

matters into sugar, which was commenced by the saliva. Bernard maintains that it also exercises the more important office of emulsifying or saponifying the neutral fatty matters contained in the food, by decomposing them into glycerine and their respective fatty acids, and so rendering them absorbable.' But the latest experimenters are agreed only in regard to the first result, and the chief office of the pancreatic secretion in digestion still awaits determination.

§ 340. Peritoneum and appendages in Mammalia.-The abdomen, as a definite and circumscribed visceral chamber, is peculiar to the present class: the heart and other thoracic viscera are shut out by the complete transverse septum or diaphragm' from the major part of the trunk-cavity, to which the term 'abdomen' is now restricted. The serous membrane called peritoneum,'

k

387

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h

k

first lumbar vertebra; Human. CCXXXV.

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which lines this cavity, is reflected from the walls upon the principal abdominal viscera to some of which it gives a complete, to others a partial, investment. In the human subject the peritoneum, as in the section shown in fig. 387, passes over the fore part of the abdominal aorta, i, the postcaval, h, and the kidneys, k, k; but is reflected so as to inclose the liver, stomach, spleen, and major Transverse section of abdomen through the part of the intestinal canal: it is continued from the transverse fissure of the liver upon the lesser curvature of the stomach to form the gastrohepatic omentum. At the level of the section figured, one part, f, is seen passing forward from the left kidney to enclose the spleen, b, and the stomach, a: the opposite border, e, is the part of the lesser omentum inclosing the hepatic duct and vessels, c. Another fold of peritoneum is reflected from the upper and fore part of the abdomen upon the umbilical vein of the foetus, which afterwards degenerates into the round ligament,' d; the supporting fold, g, being continued into the suspensory fissure of the liver, and forming its falciform' ligament: other folds continued from the diaphragm upon the opposed convexity of the liver are its 'coronary and triangular' ligaments. The lesser omentum, more properly the 'mesogaster,' or peritoneal fold which mainly suspends the stomach and conveys thereto its vessels, also covers and suspends the spleen; and this part of the mesogaster is termed the gastrosplenic omentum,' of which, in Man, only the left or outer layer forms

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388

the splenic covering. Both layers recede to include the stomach, fig. 388, b, whence they are continued from the line of the greater curvature over the fore part of the abdomen, and are folded back to the colon, in the form of a large flap or apron, including vessels and more or less fat, forming the great omentum,' ib. o, o: it is peculiar to the Mammalia, coexists with the diaphragm, and may have useful relations as insulating the peristaltically winding intestines from the constant respiratory movements of the abdominal walls. The posterior returning folds of the omentum meet the transverse arch of the colon, recede and embrace that intestine, as the anterior or descending folds had embraced the stomach; the colonic folds are continued back as a suspensory mesocolon;' the upper layer of the fold passes over the fore part of the duodenum and pancreas to the posterior abdominal walls, the lower layer is continued a short way down those walls, and is again reflected forward to the small intestines as the anterior or upper layer of their suspending fold called 'mesentery.' The relations of the peritoneum to the pelvic viscera show no class-specialities. Large omental processes with accumulated fat are never continued from the urinary bladder, and rarely from the pelvic or other regions of the abdominal walls, as they are in most Reptilia: small ones from the serous coat of the large intestine are developed in many Ungulates, dices epiploica' in the human subject. abdomen communicates with the mucous canal of the oviducts or 'fallopian tubes,' but is elsewhere closed in the female, and is a shut sac in the male mammal. Productions of this sac, however, accompany the testes into the scrotum; but are insulated by obliteration of the canal of the spermatic cord in Man.

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6

and are called appenThe serous sac of the

The above leading features in the disposition of the peritoneum offer modifications in the present class. In the insectivorous

1 xx. vol. iii. pt. ii. p. 221.

matters into sugar, which was commenced by the saliva. Bernard maintains that it also exercises the more important office of emulsifying or saponifying the neutral fatty matters contained in the food, by decomposing them into glycerine and their respective fatty acids, and so rendering them absorbable.' But the latest experimenters are agreed only in regard to the first result, and the chief office of the pancreatic secretion in digestion still awaits determination.

§ 340. Peritoneum and appendages in Mammalia.-The abdomen, as a definite and circumscribed visceral chamber, is peculiar to the present class: the heart and other thoracic viscera are shut out by the complete transverse septum or diaphragm' from the major part of the trunk-cavity, to which the term abdomen' is now restricted. The serous membrane called peritoneum,"

a

387

9

k

first lumbar vertebra; Human. CCXXXV.

which lines this cavity, is reflected from the walls upon the principal abdominal viscera to some of which it gives a complete, to others a partial, investment. In the human subject the peritoneum, as in the section shown in fig. 387, passes over the fore part of the abdominal aorta, i, the postcaval, h, and the kidneys, k, k; but is reflected so as to inclose the liver, stomach, spleen, and major Transverse section of abdomen through the part of the intestinal canal: it is continued from the transverse fissure of the liver upon the lesser curvature of the stomach to form the gastrohepatic omentum. At the level of the section figured, one part, f, is seen passing forward from the left kidney to enclose the spleen, b, and the stomach, a: the opposite border, e, is the part of the lesser omentum inclosing the hepatic duct and vessels, c. Another fold of peritoneum is reflected from the upper and fore part of the abdomen upon the umbilical vein of the foetus, which afterwards degenerates into the 'round ligament,' d; the supporting fold, g, being continued into the suspensory fissure of the liver, and forming its falciform' ligament: other folds continued from the diaphragm upon the opposed convexity of the liver are its 'coronary' and triangular' ligaments. The lesser omentum, more properly the 'mesogaster,' or peritoneal fold which mainly suspends the stomach and conveys thereto its vessels, also covers and suspends the spleen; and this part of the mesogaster is termed the 'gastrosplenic omentum,' of which, in Man, only the left or outer layer forms

' CLXIV".

388

the splenic covering. Both layers recede to include the stomach, fig. 388, b, whence they are continued from the line of the greater curvature over the fore part of the abdomen, and are folded back to the colon, in the form of a large flap or apron, including vessels and more or less fat, forming the great omentum,' ib. o, o: it is peculiar to the Mammalia, coexists with the diaphragm, and may have useful relations as insulating the peristaltically winding intestines from the constant respiratory movements of the abdominal walls. The posterior returning folds of the omentum meet the transverse arch of the colon, recede and embrace that intestine, as the anterior or descending folds had embraced the stomach; the colonic folds are continued back as a suspensory mesocolon;' the upper layer of the fold passes over the fore part of the duodenum and pancreas to the posterior abdominal walls, the lower layer is continued a short way down those walls, and is again reflected forward to the small intestines as the anterior or upper layer of their suspending fold called 'mesentery.' The relations of the peritoneum to the pelvic viscera show no class-specialities. Large omental processes with accumulated fat are never continued from the urinary bladder, and rarely from the pelvic or other regions of the abdominal walls, as they are in most Reptilia: small ones from the serous coat of the large intestine are developed in many Ungulates, and are called appendices epiploica' in the human subject. The serous sac of the abdomen communicates with the mucous canal of the oviducts or fallopian tubes,' but is elsewhere closed in the female, and is a shut sac in the male mammal. Productions of this sac, however, accompany the testes into the scrotum; but are insulated by obliteration of the canal of the spermatic cord in Man.

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Liver raised to show the stomach and great omentum, Human. CXLVIII".

The above leading features in the disposition of the peritoneum offer modifications in the present class. In the insectivorous

1 xx. vol. iii. pt. ii. p. 221.

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