TISSUE RESPIRATION IN INVERTEBRATES 



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YEAR OF STUDY 



Fig. 2. Frequency distribution of studies on invertebrate tissue respiration from 1929 

 through 1959 arranged according to year in which the studies were published. A. Porifera: 

 Demospongiae. B. Coelenterata: Hydrozoa, Scyphozoa, Anthozoa. C. Aschelminthes : 

 Nematoda. D. Mollusca: Gastropoda. E. Mollusca: Pelecypoda. F. Mollusca: Cephalopoda. 

 G. Annelida: Polychaeta. H. Annelida: Clitellata. I. Arthropoda: Merostomata. J. Arthro- 

 poda: Crustacea. K. Arthropoda: Insecta. L. Echinodermata: Holothuroidea. M. Frequency 

 distribution of all studies. 



