INTRODUCTION 



The review of auaerobiosis in invertebrates presented 

 in the following pages represents an attempt to give a 

 conii)rehensive picture of a many-sided problem. It is 

 divided into three parts: the first is devoted to a survey 

 of the occurrence of anaerobiosis ; in this part attention 

 is given chiefly to ecological problems; the second deals 

 with anaerobic meta1)olism and the third contains data 

 on the adaptations of invertebrates to anoxic conditions 

 and a discussion of the origin of their anaerobic func- 

 tions. The monograph is written from the biological 

 standpoint and thus intended primarily for ecologists 

 and comparative physiologists. Biochemists who, until 

 very recently, used almost exclusively vertebrate mate- 

 rial or micro-organisms for their work on anaerobiosis, 

 may find tliis book helpful as a guide in the choice of new 

 experimental animals. 



In 1934 we summarized our knowledge concerning the 

 anaerobic life of invertebrates in a review article publish- 

 ed in Ergehnisse dcr Biologie. Due to limitation of space, 

 only the subject ' ' anaerobic metabolism ' ' was fully treated 

 there. The present account of that phase of the problem 

 is based in part on this earlier paper, but the many in- 

 vestigations published in the intervening years necessi- 

 tated a great number of additions and alterations. 



In the discussion of anaerobic metabolism, it was found 

 preferable to divide the subject according to the proc- 

 esses involved, such as transition from aerobic to anaero- 

 bic metabolism, recovery from anaerobiosis, etc., rather 

 than to arrange the material according to the inverte- 

 brate phyla, as was done previously. 



The literature on anaerobiosis in invertebrates is ex- 

 tremely scattered; pertinent papers are found in zoolog- 

 ical, ecological, linniological, oceanographic, parasito- 

 logical, physiological, biochemical and bacteriological 



