THE EAIBRYOLOCiY OF THE BIRD's LUXG 451 



As to methods of growth: Aol)y, 'SO, inonopocUal; Miller, '93, 

 comparative, biuldiiig predominates in birds, septmn formation 

 secondary; Moser, '02, budding tlie uniform principle of growth 

 in birds and other vertebrates; Flint, '06, paper on mammals but 

 reviews the literature on other vertebrates and comments on the 

 method of growth in birds. 



C'ampana's thorough and (>xtensive paper of 1875 requires sepa- 

 rate mention. It is part of a general plan designed to illustrate 

 the laws of genesis and evolution, and the prinuuy title of his 

 memoir is Physiology and Respiration of Birds. Nevertheless, 

 the anatomical part is of chief importance, and it is the most 

 critical and comprehensive treatise on the structure of the adult 

 bird's lung to which we have had access. This memoir is not 

 easily accessible, and although it is commonly mentioned in the 

 literature lists, it has, unfortunateh", been little read. C'ampana 

 makes an illuminating analysis of the bronchial passages, tracing 

 their ramifications in detail and making an especial point of the 

 bronchial circuits which unite the various divisions of the bronchi 

 into a plexus of intercommunicating passages. He also noticed 

 the recurrent bronchi but without understanding their signifi- 

 cance. Further mention of this point will be made later, and, 

 also, his classification of bronchi will be explained in our section 

 on the bronchial tree. 



F. E. Schulze in 1911 published an important paper on the com- 

 parative anatomy of the air-sacs in the adult and for the first 

 time ('09) described the recurrent bronchi and pointed out their 

 physiological office. His excellent methods of injection with 

 metal and celloidin are described in detail. 



The most recent important contribution to the morphology of 

 the bird's lung is the paper of Juillet published in 1912. This is 

 a comprehensive treatise embracing an anatomical, embryologi- 

 cal, histological and comparative study of the avian lung. It 

 contains a re\iew of previous work and a list of the literature. 

 Its most significant feature is the description of recurrent bron- 

 chi (discovered by Schulze, '09 and '11) growing from the air- 

 sacs into the lungs and anastomosing with the parabronchi of 

 ecto, ento and laterobronchi. He used metallic injections of 



