BIOLOGY AND MEDICINE—CHANDLER 329 
cation and sanitary sewage disposal have developed. Whereas in 
1900 the American death rate from typhoid was 36 per 100,000, today 
it is about 1 per 100,000, and in 1942 more than half of our large cities 
had not a single typhoid death. 
Milk and food sanitation are even more recent developments. Eyen 
95 years ago a child ran the risk of acquiring disease every time he 
drank a glass of milk; today the greater part of the milk supply in 
almost every city is pasteurized, and many cities can boast of having 
no raw milk, . 
Just 50 years ago two American workers, Smith and Kilbourne, 
laid the foundation stone for medical entomology when they demon- 
strated the transmission of a disease—Texas fever of cattle—by means 
of atick. Five years after that the mosquito transmission of malaria 
was proved and then, at the turn of the century, came the brilliant work 
of an American Army commission in Havana, proving the transmission 
of yellow fever by mosquitoes. 
Today medical entomology plays a large part in our lives. By con- 
trol of insects, ticks, or mites we are able to control, in some cases 
almost to exterminate, many important diseases, including some of 
the most.important. I need only mention the prevention of malaria, 
yellow fever, and dengue by mosquito control, of epidemic typhus and 
relapsing fever by delousing methods, of plague and endemic typhus 
by control of rats and fleas, and of dysentery by fly eradication. 
Already we have become so accustomed to the benefits from all 
these protective devices that we take them for granted. Only when 
circumstances interfere with their practice, as is often the case in war, 
do we realize how much we depend on them. It was dysentery, not 
the Turks, that defeated the British at Gallipoli, and it was dysentery 
and malaria, not the Japs, that defeated our own troops at Bataan. 
As we go on into the future, preventive medicine will play a larger 
and larger part in our lives. Instead of being a secondary and rela- 
tively unimportant part in the curriculum of our medical schools, I 
predict that we shall have many schools devoted primarily if not 
exclusively to this fast-growing branch of medical science, which is 
still so young that it is seldom allowed to stand on its own feet. The 
‘subjects taught will be very largely biological ones, such as medical 
entomology, helminthology, protozoology, bacteriology, immunology, 
the newly developed field of aerobiology, and methods of sterilization 
and disinfection which are also a branch of biology, since they deal 
with the destruction of life. 
In addition to the categories of discoveries in biology that I have 
already mentioned, there are other fields of biological research which 
are making valuable contributions to both preventive and therapeutic 
medicine. I have time only to mention in passing a few of the 
discoveries made in the year 1942. 
