1915] Wheeler and Williams — Nnc Zealand Glou-Worm 41 



logically because a single, definite organ is formed by the union 

 or "allelotaxis" of parts of four discrete structures in a manner 

 somewhat analogous to that of the formation of the pituitary 

 body of the Mammalian embryo, and physiologically, because in 

 no other insect are the Malpighian tubules known to have a photo- 

 genetic function. Still the assumption of this unusual function 

 does not at present come as a very great surprise, because, though 

 the Malpighian tubules seem to be purely excretory in the great 

 majority of insects, several cases have recently come to light of 

 their acquisition of another function. Thus it has been shown that 

 in larvae belonging to widely different orders, such as Chrysopa, 

 Myrmeleon and Sisyra among the Neuroptera, and Lebia and 

 probably also Phytonomiis and other Rhynchophora among the 

 Coleoptera, portions of the Malpighian tubules have taken on a 

 secretory function and produce the silk from which the cocoon is 

 spun. The Malpighian tubules of insects are, therefore, func- 

 tionally more plastic organs than we had supposed and present 

 in this respect a certain analogy to the fat-body, which commonly 

 combines the functions of heematopoesis, and the storing of fatty 

 and albuminoid substances and urates. Less frequently, however, 

 the fat-body shows a development of certain of its parts into photo- 

 genetic organs (Lampyridse) and into isolated cells (mycetocytes 

 of Blattidse) or organ-like cell-aggregates (mycetomata of many 

 Homoptera), which serve as the habitacula of symbiotic Bacteria 

 and Saccharomycetes. f"* , ► 



The only other luminous Mycetophilid to which we have been 

 able to find a reference in the literature is Ceroplatus sesioides, 

 described many years ago by Wahlberg (1849) from Sweden.' ;,The 

 larvae of this insect live gregariously beneath a glutinous web on 

 the under surfaces of mushrooms {Polyporvs fomentarius). Wahl- 

 berg found the whole body to be luminous in the larval and pupal 

 but not in the imaginal stage. His brief account would seem to 

 indicate that photogenesis in this species, as in certain Chirono- 

 midse, may be due to the presence of phosphorescent Bacteria. 



We have endeavored to discover the nature of the food of the 

 larval Bolito'phila liiminosa from examination of the contents of 

 the alimentary tract both in dissections and sections and have 

 found that the creature undoubtedly subsists on insects. The 

 intestine in all the specimens examined was loosely filled with 



