H. M. Woodcock 
151 
inverted commas when the references are to accounts of such parasites 
from non-blood-sucking Insects—including, it will be seen, the reference 
to Miss Porter’s own paper. In these cases they are given as indicating 
real genera. It is only where such forms are described from blood-sucking 
hosts that the inverted commas are used. Again, to leave the Record, 
in my own article on Avian Haemoprotozoa, to which Miss Porter also 
refers, on p. 713 is the following sentence: “One or two cases have been 
described, however, of the occurrence of crithidial forms in what are 
alleged to be non-sanguivorous Insects {e.g. C. gerridis, from Gerris 
fossarum, Patton); such parasites may apparently be regarded as true 
Crithidiae, by which we may understand Flagellates that have developed 
a trypanomonad condition but which are restricted to an Invertebrate 
host.” This sentence is on the page on which I mention my discovery 
of a Trypanosome in the blood of the sheep. Further, I quote the 
following sentences (p. 244) from my article, written about the be¬ 
ginning of 1908, on the Haemoflagellates in Lankester’s Treatise on 
Zoology, vol. l. Protozoa, to which Miss Porter also makes reference: 
“ Hence, summing up, there can be little doubt that certain of these 
parasites of mosquitoes, especially those with trypaniform characters, are 
connected with some Vertebrate host, just as are those of other blood¬ 
sucking Invertebrates. At the same time, it is also probable that some 
of the (typical) Herpetomonads found {e.g. those occurring in larvae, such 
as Patton’s form, also certain forms described by the Sergents) are simply 
and primarily parasites of the Insect. Lastly, it is, of course, possible 
that such a parasite may have developed a trypaniform condition as an 
adaptation to the food of a sanguivorous Insect, without, however, hav¬ 
ing become able to live in the Vertebrate host; but so far no example 
of such a case is definitely known.” (I may say in passing, with regard 
to the last sentence, that I would not go so far in that direction to-day; 
as I discussed in my recent paper on Avian parasites, I consider the 
occurrence of a trypaniform phase in a blood-sucking Insect is almost 
conclusive indication that the parasite in question is a Trypanosome.) 
It is extremely doubtful, indeed, whether even any of the trypano¬ 
monad (“ crithidial ”) forms found in blood-sucking Insects can be 
regarded as independent. It is true that I have not worked personally 
on genuine crithidial or herpetomonad parasites from non-blood-suck¬ 
ing Insects. But I have paid considerable attention to the characteristic 
developmental phases of blood-Trypanosomes, which occur both in cultures 
and in the Invertebrate hosts. And knowing what I do about such 
forms, as soon as I observed and studied “ Grithidia ” melophagia occurring 
