W. S. Patton and C. Strickland 
323 
Without actually repeating Schaudinn’s experiments at Rovigno it 
is quite impossible to unravel his elaborate paper and to say whether he 
was dealing with a Herpetomonas or a Grithidia as well, not to mention 
the possible presence of Spirochaeta culicis in his mosquitoes 1 . 
Following Schaudinn’s work, Prowazek (1904) claimed to have 
discovered the development of T. letoisi in the rat louse, Haematopinus 
spinulosus ; but no subsequent observers, so far as we know, have 
found these developmental forms in rat lice. We have dissected and 
examined a large number of Haematopinus spinulosus from rats well 
infected with T. lewisi, but beyond finding unchanged 2 and degenerating 
trypanosomes we have never seen any of the forms described by 
Prowazek. One of us has also endeavoured to trace out the development 
of T. lewisi in rat lice, Haematopinus sp. ?, in Madras with negative 
results. We are therefore forced to the conclusion that Prowazek has 
described part of the life-cycle of a natural flagellate, Grithidia , of 
Haematopinus spinulosus, and as such we believe it has no connection 
with Trypanosoma lewisi. We have examined Prowazek’s figures and 
have no hesitation in saying they are exactly similar to appearances 
seen in other insects infected with Grithidia. For instance his figure 53 
at once recalls an agglomerated mass of Grithidia such as one of us (1908) 
has recently depicted in the case of Grithidia gerridis ; his figure 44 we 
would regard as a typical adult Grithidia, and his fig. 42, as a young form 
showing the development of the flagellum. It is important to note that 
Prowazek was unable to infect rats with lice which presumably had 
these developmental forms in them, nor does he mention the occurrence 
or not of these Grithidia in lice from rats uninfected with T. lewisi. 
It is therefore of the utmost importance that this work of Prowazek 
should be confirmed or otherwise by those who have the opportunity of 
searching for this Grithidia of Haematopinus spinulosus in lice off rats 
from the same localities Prowazek obtained his 40 rats, viz. Berlin, 
Trieste and St Pelagio near Rovigno. We have searched so far in vain 
for this parasite in England. It is quite possible it is localised in its 
distribution. 
The next important work on the development of Trypanosomes is 
that of Koch (1905), Gray and the late Captain Tulloch (1905). These 
1 In this connection see also Ross (1906, pp. 96, 101), Nuttall (1906, p. 109), Novy, 
MacNeal and Torrey (1906, p. 110). 
2 By this term we mean we have never seen parasites exhibiting changes such as occur 
in the pre-Jlagellate stages of Herpetomonas or Crithiclia. We have certainly seen thin 
active trypanosomes which appear to have resulted from longitudinal division of ordinary 
forms. 
