PERISTALSIS 



6060 



Periscope. Instrument invented by H. A. Silver, of Cincinnati, U.S.A., 

 constructed on the principles of a periscope, for showing on a screen to 

 students of surgery an operation being performed in an adjoining room. 

 Rigbt, diagrams illustrating submarine. Fig. 1, and field, Fig. 2, periscopes. 

 In each the picture enters at A, is reflected down by prism B to prism C, thence 

 to eye-piece D. In submarine instruments : E is valve to shut out water if 

 periscope is shot away; F, wheel to rotate instrument 



position or enabling an observer to 

 see over obstructions. It consists 

 usually of reflecting mirrors or 

 prisms fixed in a tube, one set of 

 mirrors reflecting the object down 

 the tube and the other to the eye 

 of the observer. The submarine 

 periscope has additional lenses in 

 the tube itself and a special eye- 

 piece. The trench or field peri- 

 scope, extensively used in the Great 

 War, consisted of two mirrors fixed 

 at the ends of a collapsible frame- 

 work. See Camera Obscura ; 

 Submarine. 



Peristalsis (Gr. peri, around; 

 slalsis, compression). Rhythmic 

 contractions which travel like 

 waves along muscular fibres, ex- 

 hibited only by involuntary mus- 

 cles. Peristalsis of the intestine 

 plays an important part in mixing 



FIG. 1 



Liver 



Omenial Oursa 

 Siomach 

 'J'ancreas 

 Duodenum 



-;-Jra.nsverse (Colon 



.' I'.'-eater 



owentum 



^Vs/wa// intestine 

 \-Peritoneum 

 tm-Rectum 



Peritoneum. Diagram showing the 



general relation of the peritoneum 



to the adjacent organs 



the contents with the 

 digestive juices and 

 forcing the material 

 along the canal. The 

 movements of the heart are a more 

 complicated form of peristalsis. 



Peritoneum (Gr. periteinein, 

 to stretch around). Serous mem- 

 brane which Iine3 the walls of the 

 abdominal cavity ind is reflected 

 over the internal ., gans, so as to 

 cover them more or less com- 

 pletely. The part lining the cavity 

 is known as the parietal layer, and 

 that covering the organs as the 

 visceral layer. Folds of the 

 peritoneum which are connected 

 with the stomach are known as 

 omenta. The largest of these con- 

 nects the stomach with the trans- 

 verse colon, and is known as the 

 greater omentum. The term mesen- 

 tery is applied to any fold of the 

 peritoneum which attaches the 

 intestine to the posterior wall of 

 the abdomen. Reflections of the 

 peritoneum from the abdominal 

 walls on to viscera other than the 

 intestine are called ligaments. The 



function of the peri- _ 



toneum is to facili- j 

 tate the peristaltic j 

 movements of the i 

 intestine. 



Peritonitis. In- 

 flammation of the 

 peritoneum. It re- 

 sults from injury of 

 the membrane or 

 extension of disease 

 from one of the 

 abdominal organs. 

 Hence it may arise 

 from appendicitis, 

 obstruction orulcer- 

 ation of the bowel, 



PERIVALE 



strangulated hernia, cancer, etc. 

 Most often the infecting organism 

 is the Bacillus coli, which is nor- 

 mally present in the intestine, and, 

 when the walls of that 

 canal are injured or 

 diseased, is able to 

 make its way through 

 to the peritoneum. Tu- 

 bercular peritonitis is an- 

 other form which is not 

 uncommon in children. 

 Peritonitis may be general, 

 affecting a large extent of 

 the membrane, or local, i.e. 

 limited to the neighbour- 

 hood of an inflamed organ, 

 and it may be either acute 

 or chronic. 



The symptoms of acute 

 peritonitis are severe and 

 continuous pain in the 

 abdomen, often with a 

 rise of temperature. 

 Vomiting is a 

 marked symptom. 

 In acute cases a 

 fatal termina- 

 tion may oc- 

 cur within a 

 few hours. Where 

 perforation of the 

 bowel is suspected, 

 operative treat- 

 ment is the only 

 hope, and similar 

 treatment is nearly 

 always advisable 

 where appendicitis 

 is believed to be the cause of the 

 symptoms. Chronic localised peri- 

 tonitis may be treated with plasters 

 and iodine, and if adhesions have 

 formed between two contiguous 

 surfaces of the peritoneum, opera- 

 tive treatment may be indicated. 



Perivale OR GREENFORD PARVA. 

 Hamlet of Middlesex, England. It 

 is on the N. bank of the Brent, 

 between Castlebar Hill, W. Baling, 

 and Greenford Green, covers 626 

 acres, mostly farm land, and in 

 early times was famous for its 

 wheat. The first lord of the manor 

 was Geoffrey de Mandeville. The 

 tiny church, partly Early English in 

 style, is said to have been founded 



Perivale, Middlesex. The wooden bridge over the Brent 



with the tiny, tree-enshrouded parish church on the 



river bank 



