I. 



INTRODUCTOR\^ REMARKS. 



II has been intended l)y this monograph to build uj) 

 a fairly complete history and criticism of the work which 

 has been done on tissue cultures, and in consideration of 

 the difficulties in writing a book like this on a field of in- 

 vestigation which is progressing so intensively, all possible 

 reservation has to be taken. In the introduction will be 

 given a short historical review — and the history of the 

 special themes will be dealt with in the various chapters. The 

 contributions and experiences made by myself are not kept 

 separately, but are added to the chapters to which they be- 

 long in order not to break up the continuity of the book. 



The history of the tissue cultures is strictly speaking 

 not more than 15 years old — and to-day there seems 

 to be only a relatively limited understanding of the im- 

 portance and significance of the tissue cultivation as a 

 method for making elementary and fundamental studies 

 of the physiology and pathology of higher organisms. 



The one-celled organism has been studied and submit- 

 ted to a thorough investigation in the belief, that a simple 

 organism is easier to understand, but Ihiugs seem to prove 

 that the one-celled organism is not so simple. In the 

 highly differentiated organism the circumstances are en- 

 tirely different and probably simpler because we perceive 

 some kinds of elements (cellgroujis or organs) and to a 

 certain extent understand their work. Xeverthelcss the 

 physiological and pathological processes are very profound 

 and complicated matters owing to the many unknown fac- 



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