Balloonist theory

Balloonist theory was a theory of muscle contraction centered on the idea of explaining muscle movement by asserting that muscles contract by inflating with air or fluid.

The Greek physician Galen believed that muscles contracted due to a fluid flowing into them, and for 1500 years afterward, it was believed that nerves were hollow and that they carried fluid. Galen lived from about A.D.130 to 200.

It was the 17th century philosopher, scientist and mathematician, René Descartes, who was explain various aspects of physiology such as the reflex arc, proposed that "animal spirits" flowed into muscle and were responsible for their contraction. In extending his speculations beyond the notions of his predecessors, Descartes relied extensively upon mathematical and mechanical models. He postulated that the heart supplied "animal spirits" to the nerves, which conveyed the spirits to the muscles, very much as water is conducted through pipes.

In 1667, Thomas Willis, a London physician, proposed that muscles may expand by the reaction of animal spirits with vital spirits. Although his speculations about the anatomical sites of reflection, memory, and phantasy had little enduring scientific impact, his investigations did contribute important information about the blood supply to the brain. The ring of blood ves-sels which he described at the base of the brain continues to bear his name (the circleof Willis) and still is an important landmarkof brain anatomy.

The end of the "balloonist" theories of nerve-muscle activities came, after Jan Swammerdam, a Dutch anatomist famous for working with insects, struck the first important blow against the balloonist theory. Jan Swammerdam, in the 1667, performed a most elegant series of experiments on this point, and proved that contracting muscles were not swollen by any influx of fluids from nerves.

Francis Glisson (1597-1677) disproved balloonist theories of nerve function by submerging a man's arm in water and measuring the displacement of water when the muscles were con-tracted. Because no change in water level could be observed, Glisson concluded that muscle contraction was not the result of fluid flowing into the muscle as was commonly thought.

The invention of the microscope allowed preparations of nerves to be viewed at high magnification, showing that they are not hollow.

In 1791, Luigi Galvani learned that frogs' muscles could be made to move by the application of electricity. In 1848, Emil du Bois-Reymond was the first to demonstrate that the nervous effect was an electrical phenomenon and that a wave of electrical negativity, an action potential, passes down the nerve.

Balloonist theory

History of genetics

Hippocrates has developed a theory resembling that later proposed by Darwin, who called it ‘pangenesis’. 

According to this view, each part of the body produces something which is then somehow collected in the ‘semen’, the germ cells.

Anaxagoras, the Athenian philosopher (500-428 BC) had similar views: …’in the same semen are contained hairs, nails, veins, arteries, tendons and their bones, albeit invisible as their particles are so small’. 

A comprehensive theory of inheritance was developed by Aristotle. He also believed in a qualitatively different contribution by the male and the female principles to procreation.

More or less casual observations on natural or accidental hybrids in plants were made over a long period, beginning with the observations of Cotton Mather on maize in 1716.

In 1857, Gregor Johann Mendel began his famous study of the pea plants in his garden; by 1866 he would publish the results of his cross-breeding experiments, the first step in understanding heredity and how it passed from one generation to another. He founded the concept of the gene, which has proved so fertile ever since.

Eventually, scientist discovered a substance that every living organism carries within its cells – DNA. The discovery of DNA’s double-helical structure changed the way genetics was done, with a profound shift to molecular interpretations of the gen and its function.

James D. Watson, Francis Crick and Maurice Wilkins held that the structure settled the question that DNA is the genetic material. The structure immediately suggested to them how genes can replicate themselves.

In 1944, Oswald Theodore Avery, Colin MacLeod, and Maclyn McCrathy discovered that DNA was the special hereditary material that almost all living organisms need to reproduce and survive.
History of genetics

History of Immunology

History of Immunology
Ancient Times
Immunology studies the relationship between the body systems, pathogens, and immunity. Primitive man knew about disease and its ravages. The Babylonian Epic of Gilgamesh (2000 B.C. – Mesopotamian hero) records the presence of pestilence and disease. The other writings from old dynasties of ancient Egypt, one finds even more descriptions of disease. They even can identify the disease. In those days, disease and pestilence was punishment rendering as a result of “bad deeds” or “evil thoughts”. Even in the Old Testament is filled with pestilence that God wrought upon those who “crossed” him. From these writings, it is equally apparent that man knew that once he had been afflicted with disease, if he survived, he was normally not able to contract it again.

In 430 B.C. Thucydides recorded that while the plaque was raging in Athens, the sick and dying would have received no attention had it not been for those individuals who had already contracted the disease and recovered and recognized their “immune” status. Beginning around 1000 A.D., the ancient Chinese practiced a form of immunization by inhaling dried powders derived from the crusts of smallpox lesions. Around the fifteenth century, a practice of applying powdered smallpox "crusts" and inserting them with a pin or “poking” device into the skin became commonplace. The process was referred to as variolation and became quite common in the Middle East. However, the primary intent of variolation was that of “preserving” the beauty of their daughters and no mention was made of saving lives.

Modern Times
In 1798, Edward Jenner inoculated a young man by named James Phipps with material obtained from a cowpox lesion. The results were conclusive but were met with great resistance by the Church.

It is the first demonstration of vaccination (smallpox vaccination). Jenner was a physician who practiced in the rural English countryside. As a country doctor, he was familiar with the region’s medical “old wives tales.” One of which was that milkmaids who had caught cowpox never became infected with the more serious smallpox. Jenner suspected there to be a connection between the fact that milkmaids were commonly known to get cowpox, but not smallpox. That’s why he decided to try this theory by pacing the scab from a cowpox lesion into a cut made in arm of a young man James Phipps.

In 1840 the first modern proposal of the germ theory of disease was proposed Jakob Henle. He was a German physician, pathologist and anatomist. He is credited with the discovery of the loop of Henle in the kidney.

Louis Pasteur played a pivotal role in the evolution of the science. While Pasteur's work at the Pasteur Institute in Paris was concerned with bacterial infectious disease, he was most concerned with the prevention of diseases that bacteria caused and how the human body was changed subsequent to infection so as to resist further insults. Louis Pasteur became the first experimental immunologist.

In 1900, Paul Ehrlich who was a German Scientist proposed antibody formation theory. Ehrlich predicted autoimmunity calling it “horror autotoxicus”. He is the one coined the term of “chemotherapy”.

Kendall A. Smith in 1983 discovered of the first interleukins 1 and 2.
History of Immunology