Bronchiectasis is reasonably common with pulmonary diseases of man, particularly of chronic character, but is certainly not frequent among animals. Under the first group (a) we can record one case, a Siberian tiger which died of enteritis and its complications to which were added a mild inactive bronchitis and a bronchiectasis of diffuse distribution. The lungs were irregular in shape, dull, gray-red in color and gave a variable boggy and vesicular sensation to the fingers. On opening the lung, dilatations of the bronchi were found, affecting chiefly the larger secondaries but apparently not the bronchioles. Parasites were not found nor were inflammatory reactions apparently adequate to explain the distentions, so that we looked upon this case as congenital. Cases coming under the headings b and c are not recorded. Inflammation almost certainly represents the most important single factor in the pathogenesis of this lesion and could be demonstrated in two cases, a Clouded Leopard (_Felis nebulosa_) and a Red River Hog (_Potamochærus porcus_). While I feel that parasites probably laid the foundation for the dilatations in these cases, none were found after, in one case at least, a very thorough search, although in the second animal a single cyst of _Cysticercus tenuicollis_ was found in the peritoneum. In both animals there was a low grade interstitial pneumonitis and peribronchitis with dilatations of the middle sized and end bronchi, these being supplied with thick walls but containing very scanty secretion. We have on record chronic ulcerative pulmonary tuberculosis in six primates, two carnivores and nine ungulates. It is highly probable that among this number some cases of ulcerative bronchiectasis occurred but if so they were not conspicuous enough to mention in the diagnosis and in only two protocols do I find a discussion thereof, once in a monkey and once in a carnivore. All the cases of our records were diffuse ectasias, fusiform, or irregular and none of the distinct saccular variety. From the foregoing facts it would seem that in human cases more weight should be laid to the effect of the dilating power of coughing and its preparatory exertions. While I am aware that the comparative incidence of human and lower animal bronchiectasis cannot be based upon the meager figures at our command, these dilatations certainly can be expected in a general autopsy service more in man than in lower animals. Chronic bronchitis is relatively rare, aside from the verminous varieties. I have seen little retained exudate in the bronchi, probably because quadrupeds seem with ease to raise and swallow the secretions. Nor do animals give vent to paroxysms of coughing such as the human being feels forced to do. Suggestive deductions from these points are that inflammation is the principal factor in acquired bronchiectasis and that the retention of secretion with violent inspiratory efforts are potent in man for the dilatation of the tubes. THE LUNGS.