38 WILLIAM A. LOCY AND OLOF LARSELL 



The reconstruction method has the advantage of giving relatively 

 large models, but it is difficult and protracted. Injection with 

 air, described under 'technique,' is simpler, it can be repeated 

 indefinitely with the same specimen and gives clear pictures of the 

 minuter details. 



The researches of Sappey ('47) laid the foundation for those of 

 Campana ('75) which, in particular, mark the next advance in our 

 knowledge of the bronchial tree. These investigations were car- 

 ried out on the adult lung and resulted in accurate figures and ex- 

 tended descriptions. The quahty of Campana's work has been 

 spoken of before, but too great emphasis can not be laid on the 

 thoroughness of his anatomical analysis. It is now fifty years 

 in the past and on that account, coupled with the fact that his 

 memoir is not easily obtainable, it is hkely to be slighted. The 

 memoir is complete and critical for the adult stage embracing 

 the intra- and extrapulmonary features, the bronchial tree, the 

 air-sacs, their orifices and the bronchial circuits. Campana was 

 apparently the first to fully grasp the idea of bronchial circuits. 

 The earlier observers referred to, indicated the beginning of bron- 

 chial branches but their conception was apparently that of a true 

 bronchial tree comparable to that of mammals. Schulze ('71), 

 in giving a picture of the histology of the bird lung showing among 

 other features the air-capillaries evidently interprets them more 

 as alveoli than as a network of connecting passages. 



Fischer ('05) studied the bronchial tree by injections and pub- 

 lished many figures of wax casts. His descriptions are terse, 

 more general than critical and are somewhat burdened with a 

 new terminology. 



It is through the investigations of Schulze (11) and Juillet ('12) 

 that we arrive finally at our present conception of the architec- 

 ture of the avian lung. Their discovery of the recurrent bronchi 

 has been sufficiently commented upon in previous pages. Juil- 

 let's investigations introduced some innovations besides recurrent 

 bronchi, as sketches of the embryonic tree of six and eight day 

 stages. He was also the first to show the method of develop- 

 ment of the recurrent bronchi, and after Schulze, to recognize 

 their significance. 



