RELATION OF ARTHROPODS-TO PATHOLOGY—-MAROTEL. 707 
that the law formulated in the beginning by Grassi, namely, that 
there is no malaria without Anophelines, is always true. At present, 
if one wishes to deny the rdle of mosquitoes in the propagation of 
fevers, it is necessary to deny the evidence. 
Alongside the malaria of man, we place the malaria of birds, not 
that it is of great medical importance, but because, although it occurs 
in quite a large number of wild birds (sparrows, birds of prey, etc.), 
it has scarcely been noticed thus far in a single domestic bird except 
the pigeon, and in one game bird, the partridge. It has had a 
scientific interest of the first rank, however, because through it was 
first discovered the inoculation réle of mosquitoes. It was this which 
opened the door to the important researches which we have men- 
tioned on human malaria. 
Malaria in birds is almost always due to an 
endoglobular heematozoan very closely allied to 
that occurring in man—the Plasmodium danil- wR. 3—Rea corgeaere 
ewskyi (fig. 3). of a pigeon infected 
k = oO. 2 > : ; by the parasite of 
Some months before Grassi’s investigations avian. malavisleprae 
were undertaken, Ross showed that this parasite — medium danilewskyi. 
5 ° Oe ae : n, Nucleus of the cor- 
was introduced into birds by mosquitoes be- mance: Pete 
longing to the genus Culex, and especially b hematozoan, contain- 
5 > 9 
CG ie ‘ poh tyes tl n ' : s b nd: t ing its own nucleus 
Culex pipiens, the common species so abundan ant pienette nee 
in our part of the world. By this remarkable 
discovery, Ross became the real originator of the studies which fol- 
lowed relative to the role of insects in the transmission of disease. 
For this reason, I must mention his name in this review. in order to 
give him the credit that is due him. 
B. FILARIASIS. 
The filarias are round, filiform worms whose habitat, both as re- 
gards the organ and the species, varies extremely. Thus, one may 
find them in the blood, the lymph, the serous membranes, the glands, 
the connective tissue, etc., both in man and in the domestic animals. 
That which should be remembered from the outset is that whatever 
may be the location of the adult, the embryoes of many of these forms 
live in the blood. This is the case, notably, with a filaria of man, 
the Filaria bancrofti, which in adult age is found in the lymphatic 
vessels of the skin, while its embryoes spread through the blood. 
Now, it is singular that these embryoes remain hidden during the 
day in the large, deep vessels, and that they pass out into the periferal 
circulation in the night, or strictly speaking, during sleep. This. 
circumstance led Manson to think that the agent of transmission 
must be a bloodsucking insect of nocturnal habits, and to recall the 
mosquitoes. The mosquito hypothesis, put forward more than twenty- 
five years ago, could be completely verified only in 1900 by the simul- 
