EOAEING. 385 



ROARING FROM MECHANICAL OBSTRUCTION IN THE AIR 

 PASSAGES. — As a result of laryngitis, bronchitis and other 

 diseases, the interior of the air passages may become rough, 

 diminished in size, or altered in structure. Thus there may be 

 thickening and even ossification of the arytenoid cartilages (which 

 form the front part of the roof of the larynx), and swelling of the 

 mucous membrane, with roaring as a result. This form of roar- 

 ing may also be caused by the presence of tumours which obstruct 

 the opening of the larynx. Such tumours sometimes cause inter- 

 mittent roaring. 



ROARING FROM MECHANICAL ALTERATION OF THE 

 SHAPE OF THE AIR PASSAGES.— I have seen this form of 

 roaring caused by an attack of osteoporosis (p. 259) which dis- 

 torted the shape of the nasal cavities. It may be due to irregular 

 or imperfect union of the edges of the wound made into the wind- 

 pipe by an operation for tracheotomy. The continued use of a 

 very tight bearing rein is said to have occasionally caused roaring, 

 by distortion of the larynx. 



ROARING FROM POISON.— Several Continental writers have 

 described cases of roaring (probably of the paralytic form), 

 caused by eating certain poisonous plants, and which were 

 complicated as a rule by other disorders. The chief plants in 

 question are : The ordinary lentil (ervum lens), bitter lentil (ervum 

 ervilia), com cookie (agrostemma githagd), and the vetchlings 

 (lathyrus cicera and lathyrus sativus) (p. 600). In lathyrus cicera, 

 these substances are chiefly oxalic acid and saponin. Oxalic acid 

 is a strong poison which acts on the nerve centres and on the heart, 

 and is foiind in sorrel and other plants. Saponin contains sapo- 

 toxin, which is a dangerous blood poison and breaks up the blood 

 corpuscles. Saponin occurs in soapwort (saponaria), Nottingham 

 catchfly (silene nutans), wild lynchis (lynchis diurna), and chiefly 

 in plants belonging to the order of Caryophyllese (pinks, chick- 

 weeds and carpet-weeds). The poisonous nature of many wild and 

 garden plants is due to the presence of saponin. 



TESTING A HORSE'S "WIND."— If the horse is a saddle 

 animal, he should be sent a strong gallop on soft ground, so as 

 to " open his pipes " and to allow the examiner, who, if possible, 

 ought to be in lie saddle, to observe the nature of his breathing. 

 If the examination be conducted on foot, the horse, after passing 

 near to the examiner, say, a oooiple of times, should be pulled up 

 sharply, and brought to him, to enable him to apply his ear close 

 to the animal's nostrils, so that he may detect any peculiarity in 



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