Seme Relations of Biology to Acjnculiure. 
435 
Perhaps the most interesting of all the Sporozoa are those forms 
which invade the blood-cells and, by the disintegration of these, 
lead to serious disease. Such forms have been found in India in 
the blood of mules suffering from an epidemic pernicious anaemia, 
the so-called Surra-disease. The comparative parasitology of the 
blood is, however, yet in its infancy. Enough has been said 
show that not only Bacteria, but low forms of animal life, furnisL 
important pathogenic organisms, and that continued comparative 
researches on the whole group of the Sporozoa are required to fill 
up the gaps in our knowledge of those forms which are pathogenic 
to domesticated animals. 
Encouragement of Scientific Work. — Dr. Victor C. Vaughan, 
professor of bacteriology in the University of Michigan, dwelt on 
the necessity of encouraging scientific work. " Science is know- 
ledge ; art is the application of knowledge. Science consists of 
facts ; art utilises these facts. Science investigates ; art adapts. 
Science is the foundation ; art is the superstructure. Science is the 
mariner who sails out over the seas of ignorance, and discovers fair 
islands and broad continents of truth ; art is the immigrant who 
comes later, and tdls the soil, and builds the cities.'' 
All living things consist of individual parts called cells. Some 
of the lowest forms of life are simple free cells, and are termed 
unicellular. In such cases, this single cell must perform all the 
vital functions. It must digest, absorb, excrete : but its range of 
functions is necessarily limited. In ascending the scale of organised 
life, a multiplication and differentiation of cells becomes notice- 
able. In the higher animals certain cells have for their sole function 
the elaboration of the digestive juices, others are employed in 
the separation of effete and poisonous matters from the blood and 
their elimination from the system, and so on. Health is maintained 
by the proper and correlative activity of these various groups of 
cells. 
"Within the last fifteen years it has been clearly demonstrated that 
the introduction of some of the lower forms of vegetable life, called 
Bacteria, into the body of man and other animals produces disease. 
The study of these micro-organisms has brought into existence and 
developed the science of Bacteriology. A large amount of informa- 
tion has already been accumulated in this field of scientific work, 
so that the art of the preservation of health — hygiene — and the art 
of restoration to health — medicine — have benefited by many valuable 
practical applications of these scientific facts. There are numerous 
problems to be solved concerning Bacteria. What chemical altera- 
tions do they cause in the various media in which they grow ? 
What fermentations do they induce ? Why is it that an alteration in 
the environment so materially affects the virulence of some of them ? 
Why is it that the bacillus of anthrax is so invariably fatal to certain 
animals whilst others enjoy perfect immunity against the same 
germ ? 
Two factors enter into the causation of infectious disease. First, 
