author's abstract of this paper issued by 

 the bibliographic service november 10. 



EXPERIMENTAL STUDIES ON THE ORIGIN OF 

 MONSTERS 1 



II. REGARDING THE MORPHOGENESIS OF DUPLICITIES 2 

 E. I. WERBER 



From the Osborn Zoological Laboratory, Yale University 



TWENTY-SEVEN FIGURES 



INTRODUCTION 



In a recent publication (Werber, '16 b) I have attempted 

 an etiology of monstrous development and an analysis of the 

 morphogenetic factors underlying it. The observations there 

 recorded and the theoretical conclusions based on them per- 

 tained largely to terata of the head, but some other experimen- 

 tally produced forms of pathological development have also 

 been sufficiently considered.* 



The .present paper is a continuation of this work. Its pri- 

 mary purpose is to put on record some duplicities which have 

 resulted from the employment of a chemical method. The 

 attempt is also made to account for their morphogenesis al- 

 though I am fully aware of certain possible inadequacies of our 



1 This contribution is a part of the work carried on with the aid of a grant from 

 the Bache Fund of the National Academy of Sciences in 1915. 



2 The term 'duplicity' has, unfortunately, lost its original meaning and come 

 to be employed almost exclusively in its metaphoric sense. In view of the lack 

 of an other suitable English term I propose henceforth in dealing with monozy- 

 gotic double embryos to employ it in its original meaning which I believe to be 

 proper and precise, being the equivalent of the Latin 'duplicitas' and the Ger- 

 man 'Doppelbildung.' The commonly employed term 'double monsters' ('Dop- 

 pelmissbildung') can be employed only for deformed conjoined double embryos. 



3 In a very recent paper Newman (Biological Bulletin, vol 32, No. 5, 1917) 

 makes the statement that I failed to account for such teratomata as the 'isolated 

 eye' (or the 'solitary eye'). In reply I refer the reader to pp. 541-552 of my 1916 b 

 paper where these teratomata, for the first time experimentally produced by 

 myself, are described and their morphogenesis fully accounted for. 



409 



