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said that the ventral fork serves as the stem. In consequence of this 

 method of growth the adult lung consists of main stems with lateral 

 branches . . . But it is erroneous to suppose, as did Aeby, that the 

 system of growth is stictly monopodial, it being in reality a modified 

 dichotomous system. The branches all arise by terminal forking, 

 never as outgrowths from the side of a stem." 



d'Hardiviller, from his studies on the rabbit and sheep, an- 

 nounces the following law of development: "Toutes les bronches 

 primaires, principales ou accessoires, naissent en divers points des 

 bronches souches par ramification collaterale, le bourgeon terminal des 

 bronches souches ne prenant aucune part a leur formation." These 

 principal branches then, according to d'Hardiviller, give rise to 

 secondary branches by the production of lateral buds as well as by 

 equal and unequal dichotomy. d'Hardiviller does not believe that 

 all branches of the stem are successive in their formation. 



Nicholas and Dimitrova 1897, in the sheep, describe the growth 

 of the main bronchi by lateral buds which appear successively on the 

 terminal portion of the stem bronchus. 



The results of Justesen 1900 contained in an extensive paper 

 devoted entirely to the method of growth of the bronchial tree, may 

 be given in one sentence: "die Bronchialverzweigung ist also eine 

 dichotomische", in which process he would include all branches of the 

 tree from first to last. 



The process of growth of the bronchial tree according to Narath 

 1892, 1896, 1901 is a rather complicated process. He looks upon the 

 primitive lung sac as the first production of a stem bud. When a 

 side branch is produced from the end bud a slight swelling is observed 

 on its lateral side, emphasized by the occurrence of mitosis in this 

 region. In consequence of the greater pressure at this point, the end 

 bud bends slightly in the opposite direction, that is to say, medial- 

 wards. As the new bud grows, this process increases until there is a 

 distinct kink in the axis of the stem opposite the new element. As 

 it increases in size, the side bud takes first the form of a conelike 

 projection with a rounded summit, as the stem bud grows on, then 

 the epithelial wall about its base sinks somewhat towards the axis 

 of the stem, until the daughter bud is isolated from the stem. It 

 is important to note, furthermore, that Narath considers the end 

 bud the entire terminal part of the stem up to the last wellforraed 

 lateral branch. 



In reference to the origin of the dorsal bronchi, Narath states 

 from his observations on the rabbit, that they are produced without 



