Vlll PREFACE. 



misapplied the word rudimentary, should we necessarily regard 

 this misuse as hallowed, and ever after refuse to use the word 

 in its common sense ? To such an extent has this misuse of 

 the word been carried, that even encyclopaedic dictionaries, 

 after defining the word rudiment in such a manner as to prove 

 that it is the very word we are seeking, as a rendering of the 

 idea expressed by "Anlage," give us, under the technical use 

 of the word, " In Zoology, a part or organ, the development 

 of which has been arrested (see Vestige)." It would require 

 but little trouble on the part of teachers of Biology to reinvest 

 the word ludiment with its proper meaning. By carefully 

 insisting on the use of tlie words vestigium and vestioial, or 

 their equivalents, for all abortive or reduced structures met 

 with in the. adult animal, and restricting the terms rudiment 

 and rudimentary to all growing and developing tissues and 

 organs, tliey could insure this result in a few years. We 

 have by no means always rendered "Anlage" as rudiment, for 

 we find tliat the German use of the term is not at all precise, 

 and it was often possible to express the meaning better by 

 another English word. 



The extreme looseness with which some other terms, sucli 

 as Vorderdarm, Mitteldarm, and Hinterdarm, are used in 

 German Avas unfortunately not recognised until too late. These 

 words are for the most part translated by the equally vague 

 expressions fore-, mid-, and hind-gut. Throughout the Crustacea 

 the fore-gut is co-extensive with the anterior ectodermal in- 

 vagination, the stomodaeum, and the liind-gut is similarly 

 related to the corresponding posterior invagination, the procto- 

 daeum ; the term mid-gut, however, is used in a more varied 

 sense. AVhile for the most part it is applied to the entire 

 entodermal rudiment, it is at times used for the entodermal 

 tube after the separation of the hepatic rudiment. As more 

 precise terms, Professor E. Eay Lankester proposed the words 

 enteron for the entodermal rudiment before the separation of 

 the various entodermal derivatives, and metenteron for what 

 is left of the enteric sac as the central element of the 

 alimentary canal after the separation of the outgrowths,* and 



* See Preface to English translation of Gegcnbaur's Elements of Comparative 

 Anatomy, 1878. 



