The daily morning journal and courier. [volume] (New Haven, Conn.) 1894-1907, 1902-05-05

mode of communication, and, more
over, that they are the only proved
mode of communication. How did an
| organic neXus so curious arise?
Many hundred species of mosquitoes
are known; collections from all parts
of the world recently have been brought
together and studied at the Natural
! History Museum. They are all two
winged insects, with lancet-like, pierre
ing mouth organs, their large develop
ing in stagnant water, Many of them
are harmless vegetarians, gaining their
fod by piercing the leaves and fruits of
plants, and so sucking the sweet juices.
Mosquitoes that have not got beyond
such a mode of life have comparatively
short and simple mouth organs. where
| as the blood-sucking forms possess a
| longer proboscis with more powerful
| lancets. In the ordinary course of evo-
luton from the more simple to the
| more complex it is probable that the
J blood-sucking forms have been derived
| from vegetarian ancestors. and that
| their mouth organs have gradually be-
come better adapted for the new mode
/ of obtaining nutrment. 1T Is not nee
| essary to suppose that the first victims
were warm blooded animals; for mos
! quitoes have been observed attacking
other insects as well as many cold
/ blooded creatures such as fish and
| frogs, and there must be very many
capable of piercing the skin of a mann
NAL which seldom or never have the OPP
| portunity to do so. Even in the case
of the mosquitoes which convey disease
| tot al Inc nbiaHu Xnoatorian in
| the case of the males and is at le2 st oc-
casionally so in the case of the females.
| 1t is easy to see that infinitely mi
croscopic parasites could pass from the
| host to the mosquito, and from the
| mosquito to the blood Of the host when
| the suctorial habit had been acquired,
| but we have not materials to do more
than guess as to whether the disease
germs originally belonged to the mos
quito or to the warm blooded victim.
The germs of malaria, of elephantiasis,
and of yellow fever approach more
nearly the animal kingdom than the
plant kingdom, and have numberless
allies without the parasitic habit, that
spend their lives in wa ter and mud.
Their ancestors might have gained ac-
cess to the body Of man or to that of
some allied mammal through the drink
ing water for in the tropics animals
aud men often have to be content with
water from the foulest sources Once
they had established the parasite habit,
the organisms, in correspondence with
the great Elasticity played, by such
lowly FORMS might rapidly have becom
modified into something approaching
the modern form, and the advent of the
mosquito into the chain might have
been later event The mosquito. seek
ing blood, might have gained a new
parasite from his victim. There Is
nothing but the vaguest conjecture to
lead us, but it is not likely that the
course we have sketched out was that
actually followed in the evolution of the
disease There is a considerable differ
ence between the temperature condi-
lions of the human body and those of
water, and we know that micro organ
isms are extremely susceptible to
changes of temperature. The tempera-
ture Of man is much higher than that
of the water even in tropical marshes,
as by day evaporation. and by night di
rect radiation, keep water and mud rel
atively cool. Tt seems more likely tina
the parasitic habit with its attendant
notifications, was acquired first in the
body of the mosquito. and that the
germs Of malaria or yellow fever, and of
elephantiasis We're parasites Of the
mosquito before they became parasites
of man.
The temperature of the body of an in
sect is appreciably higher and more
constant than that OF the surrounding
media, though much lower than the
human temperature, and in this respect
the mosquito might we'll have formed
stepping stone to man All mosquitoes
require water not only to deposit their
eggs. but apparently for drinking pur-
poses. and the ancestors Of the microbes
might have first reached the body of
adult mosquitoes directly. Still more
probably, however, entrance was first
gained in the larval stages. The larvae
of all mosquitoes live in stagnant wa
ter. that is to say, in the natural ances-
trail habitat of microbes. They spend a
period Of from four to ten days be-
tween the time of Matching and the
Transformation into the relatively
duiescent pupal stage, and during this
period they are vorac'ous feeders. Some
of them live on animal, and some of
them on vegetable matter. while many
of them feed almost wholly on micro
organisms. such as desmids and pro-
tococci Here. at least was opportunity
for the originally harmless ancestors of