150 HUGH GLASGOW. 



having been kept wholly free from bacteria for a considerable 

 time, developed into perfectly normal adults. His conclusions, 

 which are quite different from those of Schottelius, are: "La vie 

 sans microbe est possible pour un vertebre le poulet pourvu 

 normalement d'une riche flore microbienne. Cette vie aceptique 

 n'entraine par elle-meme aucune decheance de 1'organisme." 



Insects and other invertebrates have been employed by a 

 number of investigators, as Bogdanow, Woolman, and Delcourt 

 and Guyenot, for working out this same problem. Of these the 

 work of Delcourt and Guyenot is especially notable, for while 

 no vertebrate has, so far, been carried successfully through its 

 normal life cycle in the total absence of intestinal bacteria, these 

 authors have succeeded in keeping flies of the genus Drosophila for 

 as many as twenty generations under aseptic conditions, finding 

 that growth in the sterile cages was perfectly normal and fully 

 as rapid as in similar but contaminated cages. It also developed 

 that the mortality was remarkably reduced, the eggs almost all 

 hatching from the sterile flies, while in the septic cages whole 

 broods would frequently die. 



Bogdanow and Woolman, who also worked with flies, chiefly 

 Lucilia ccesar and Calliphora vomitoria, both succeeded in rearing 

 these insects with the exclusion of bacteria, but their conclusions 

 as to the importance of intestinal bacteria in growth and develop- 

 ment are somewhat different. Bogdanow found that, while the 

 larvae would develop under these conditions, growth was greatly 

 retarded, and practically all died at or before pupation although 

 one would occasionally pupate and develop into an undersized 

 fly. He concludes that his experiments show that bacteria, 

 probably those species which decompose protein, are necessary 

 to the normal development of these flies. 



Woolman, however, was able to carry the larvae through from 

 sterile eggs to normal adults. During the first few days after 

 hatching the growth of the sterile maggots was noticeably slower 

 than in the septic cages, but later this difference tended to dis- 

 appear, and when mature the sterile larvae showed practically 

 the length and weight typical for the species, pupated, and 

 developed into perfectly normal adults. This slight check in 

 growth shown by the maggots at first was attributed by the 



