300 DIETKTK. DKKI ( [KNCV. 



tion. Death almost invariably su]K'rveiies within a few weeks, 

 sometimes within a few day> or even honrs — with fre()uent pulse, 

 cyanosis, and (edema of the lung^s. 



Posl-niorlciii . Ippcaraiiccs. — Those described natm-all\- deal 

 with the most acute cases, and may include, singly or combined, 

 oedema of the skin and nuisculatiu-e. cyanosis of the extremities. 

 lips, and ears, subcut;uieous hcemorrhas^e, hydropericard. hydro- 

 thorax, ascites, ecchvmosis of the stomach and duodenum, dila- 

 tion and hy]iertro]:)hy of the heart with fatty degeneration of 

 cardiac muscle, (vdema of the lungs, and minor changes in the 

 ki<lne\s and other organs. The mtjst im])ortant changes are said 

 to be those of the muscles and peripheral nerves. 



Microscopically all stages of nervous degeneration may be 

 evidenced. In fresh cases the nutuber of degenerated fibres is 

 small, and at the nerve endings those hl)res adjacent to de- 

 generated muscle fibres seem to >ho\\ the most alteration. The 

 degenerative neuritis is said to concern chiefly the peroneal, tibial, 

 and saphenous nerves of the legs, ulnar, radial, and median of the 

 arms ; also the jihrenics and the \agi. The whole nervous sy.stem, 

 "however, is i)robablv affected. 



Affected muscles show all stages of degeneration and 

 atroph}-, the first indications boing a grow ing indistinctness of the 

 cross striation. 



Polyneuritis (/alliitariini, or experimental beriberi in birds, i:> 

 regarded as closely related to human beriberi. .Since the study 

 of this disease, artificially ])ro(luced by l-'.ykman in 1897, and sub- 

 se(|uently studied by innumerable other investigator.s. has done 

 .so much to clear up the question of beriberi ])roper, brief refer- 

 ence to it ma\' be made. 



rw(^ main types occur in pigeons. 



( 1 I Acute Fonii. — To begin with, a general lowering of acti- 

 vity is evident in which the bird shows disinclination to move, and 

 if disturbed runs a short distance and evidences exhaustion by 

 making use of its wings without definitely attempting to fly. This 

 latent manifestation is not always recognisable, unless, or until, 

 it passes over into the acute form projier. in which there is general 

 incoherence of movement, more es])eciall\ of the head, or con- 

 traction of the neck muscles resulting in a characteristic twist- 

 ing back of the head. Mere handling, as in cramming, is often 

 sufiicient to bring about a sudden transforniation from latent to 

 acute form, and wdien this hap])ens the neck is tisua]l\ twisted 

 back, the legs are drawn up. and the bird rolls head over heels 

 backward — a rolling which may go on continually or intermit- 

 tently for hours on end. unless restricted. The course of the 

 acute form is rapid, and the bird usually dies within 24 hours, 

 although, as we ourselves ha\e observed, s))ontaneous recovery 

 may occur if the bird is starved. A second attack, however. 

 almost inunediatel}' ensues if the bird is again fed on the causal 

 diet. Minor variations of this most distinct form mav occur, and 

 for pigeons hand-fed on about one-twentieth of their own weight 



