108 
NOTE ON THE MORPHOLOGY OF HERPETOMONAS AND 
CRITHIDIA, WITH SOME REMARKS ON “PHYSIO¬ 
LOGICAL DEGENERATION.” 
By N. H. SWELLENGREBEL, Pii.D. 
{Ilijgie7uc Institute, University of Amsterdam.) 
With 12 Diagrams. 
CONTENTS. 
PAGE 
I. Introduction, material and methods .... 108 
II. Grithidia calUphorae n. sp. ..... 110 
III. Hcrpetomonas calUphorae Swingle .... 112 
IV. General remarks ........ 123 
V. Summary.127 
I. Introduction, material and methods. 
Since the publication of Prowazek’s paper (1904), much work lias 
been done on the morphology and biology of Herpetomonads and 
Crithidiae of the alimentary tract of several flies and other insects. 
The readers of this Journal will find full accounts of the literature 
on this subject in the interesting papers of Miss Porter (1909), and 
Miss Mackinnon (1910). 
During the summer of 1910 I found two species of flagellates in the 
gut of the blue-bottle {Calliphora erythrocephala), one belonging to the 
genus Grithidia, the other to the genus Herpetomonas. Since then 
Swingle (1911) described these two forms under the name of 
Herpetomonas callijohorae. 
The general morphology of these flagellates being well known from 
the papers of Patton (1908-9), Porter, Mackinnon, Prowazek and 
others, I will not give a detailed description of the two parasites, but 
