W. S. Patton 
111 
his views. We are told in a footnote by Woodcock (p. 239) that he has 
recently been able, after an arduous investigation on the Haematozoa 
of birds, to obtain the first definite evidence in support of Schaudinn’s 
views. We shall criticise his recent findings later on. 
It will be remembered that Schaudinn, after feeding Gulex pipiens 
on the blood of the owl ( Athene noctua) infected with Halteridium 
danilewskyi, claimed to have discovered the development of the intra¬ 
cellular parasites of the owl in the stomach of the mosquito. The 
Halteridium macrogamete, after being fertilised by the microgamete 
in the stomach of the mosquito, developed into an ookinete which became 
either a male, female or neutral trypanosome. These trypanosomes 
were then found in masses at times near the oesophageal end or at the 
junction of the ileum and colon. Schaudinn described complicated 
migrations of the parasites in the body of the mosquito, the parasites 
eventually developing into forms which were prepared to pass into the 
blood of an owl when this insect next fed. 
Woodcock notes that the main criticism on Schaudinn’s work is 
based on the probability of his dealing with at least four blood 
parasites: two free parasites, a trypanosome and a spirochaete (Topfer) 
and two intracellular ones, Halteridium and Leucocytozoon. Woodcock 
however entirely omits from this list Herpetomonas culicis, Crithidia 
fasciculata and Spirochaeta culicis, merely mentioning them later on. 
We consider these are the most important parasites in connection 
with Schaudinn’s work, and we believe that the other four blood 
parasites have played a small part in Schaudinn’s complicated life 
cycles of Halteridium and Leucocytozoon. Schaudinn did not refer 
to his having excluded Herpetomonas culicis, Crithidia fascicidata 
or Spirochaeta culicis from his mosquitoes. We have shown that 
Gulicines obtain the parasites H. culicis through the larva, so that 
in order to exclude this flagellate it is not only necessary to breed 
mosquitoes, but to be particularly careful in transferring the egg-rafts 
into water, where there is no chance of the larvae ingesting cysts passed 
out in the excreta of other mosquitoes. Schaudinn’s mosquitoes were 
obtained at large at Rovigno, and we do not know whether they were 
caught as adults or hatched from larvae. It is not known at present how 
Crithidia fasciculata is transmitted from one insect to another; there is 
always the possibility that these particular flagellates may be transmitted 
hereditarily, and if this proves to be the case, the larvae would have to 
be bred from eggs laid by uninfected insects. Spirochaeta culicis, which 
we have recently found in the alimentary tract of adult Gulex pipiens in 
