9] STUDIES ON GREGARJNES KAMM 9 



true in gregarines, for many instances may be mentioned in which genera 

 are found exclusively in a single order of insects; the genus most frequently 

 present in the Acerata (Sciadophora) is found nowhere else and is highly 

 specialized and unique along a particular line. 



A gregarine has even been found in Peripatus; and the Tunicates 

 contain true septate forms. It would be interesting to know what becomes 

 of these parasites above the Tunicates whether they lose their gregarinoid 

 and take on higher characteristics, continuing to develop in vertebrates, or 

 whether the alimentary tract of the latter contain enzymes not suited to their 

 continued existence and they are thereby extinguished. 



A suggested problem is that of the possibility of the existence of greg- 

 arines in the insects found in Baltic amber; the insects being transparent 

 their presence or absence should be easily determined, and possibly some 

 of the generic characters. 



