20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



The present writer thinks improbable Noble's idea that the southern 

 frogs of Australia and those of South America evolved independently 

 from the archaic toads, and developed along parallel lines. 



So far as I can learn, the papers mentioned cover the use thus 

 far made of data from parasites in connection with the three classes 

 of problems here considered. So little has been done in this field and 

 so little has that little been known that each successive student has 

 thought himself a discoverer and a pioneer. It has been probably a 

 unique incident in biological and geographical science. There have 

 been instances of double or triple discovery — mutation, for example — 

 but sixfold independent discovery of a concept with wide significance 

 and capable of important application in further research has probably 

 not before occurred. 



We have described in outline the use that has been made of this 

 " von Ihering method." It seems well before closing this paper to 

 suggest possible further applications of the method, using other groups 

 of parasites, and to mention some specific problems needing study 

 by this method. Harrison (1928) has reviewed from this point of 

 view different groups of animal parasites considering their availability 

 for host-parasite studies. Let us include plants as well. 



Protozoa — There are, of course, many groups of Protozoa part or 

 all of whose members are parasites or commensals, having at any rate 

 an obligatory association with definite animals or plants. Among the 

 Sarcodina are many parasitic Amoebae and a few Heliozoa are inter- 

 nal parasites. I know of no use of data from these forms in studying 

 such general problems as we have had in mind. Our knowledge of 

 the taxonomy of these parasites, of their host-occurrence and of the 

 geographical distribution of l)oth parasites and hosts is inadequate, 

 but the material for such host-parasite studies in these groups seems 

 to be availa1)le. There is a considerable degree of specificity in the 

 host relations of the Endaniocbac and they are found in many groups 

 of animals. 



Multitudes of the flagellates are parasitic and probably no other 

 group presents more advantageous material for host-parasite studies. 

 Some flagellates are parasitic in plants. Although knowledge of flagel- 

 late parasites is extensive, it is ver^^ fragmentary, being almost nil 

 for many regions of the earth and far from complete for most regions 

 and for most hosts. In some groups we have enough records to begin 

 tabulating the host occurrence and geographical occurrence and scru- 

 tinizing the tables for what the}- may indicate. Probably the finest 

 groups for host-parasite studies are the termites (white ants) and the 



