MR. H. D. GELDART OX FI LARI A SANGUINIS HOMIXIS (NOCTURXa). 549 
digesting her meal and perfecting her eggs. When her eggs are 
mature, she goes to some pool of water to lay her eggs, when she 
has done so, she falls into the water and dies. Of the many 
embryo Filariee which she has swallowed, the greater part die and 
are digested with the blood ; but a few survive, these undergo 
some changes within the Mosquito, they grow larger and stouter, 
the granular mass within them becomes clearer, and internal 
organs begin to be formed, they get rid of their sheath, and their 
head and boring apparatus become stronger and more developed, 
and the first use made of the borer is to enable the embryo to 
escape from the body of the Mosquito, and it then swims freely 
through the water; if in this state the embryos are swallowed by a 
man, they bore their way from the stomach into one of the 
lymphatic vessels of their host, and if he has had the ill luck to 
swallow two who develope into male and female Filaria bancrofti, 
the female begins to breed and pours forth from an orifice in her 
neck a stream of ovoviviparous embryos, that is to say they are 
born alive, but with their egg shells still about them, these make 
their way into t lie blood-vessels of their host, lying perdiut some- 
where, no one at present knows where, during the day, and 
swarming in all the blood-vessels during the hours of darkness, 
when the intermediate host, the Mosquito, is active. In the patient 
from whom this blood was drawn, it is supposed that only one 
pair of adult Filaria >■ exist, or the embryos would be more 
numerous, in many coses there are more than one pair, for more 
than one pair have been removed from the same person, and then 
the embryos, instead of numbering half a million, amount to 
several millions. The fertile period of a female Filaria bancrofti 
continues a very long time ; one case is recorded in which it lasted 
for thirty-two years. The consequences to the unfortunate host are 
very various, sometimes no harm whatever results, but in other 
cases very serious skin diseases, leprosy, and elephantiasis neces- 
sitating severe operations, have been clearly traced to the action of 
the parasites. 
As to geographical distribution the parasite seems to girdle the 
globe within the tropics, in fact, wherever the peculiar species of 
Mosquito is present to distribute it. In West Africa a different 
kind of Filaria exists, F. (Hunt a which appears in the blood 
during the day, and of which the Mangrove Fly, a small black fly 
