Gustav Jäger was a German

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 naturalist

Natural history

Natural history is the scientific research of plants or animals, leaning more towards observational rather than experimental methods of study, and encompasses more research published in magazines than in academic journals. Grouped among the natural sciences, natural history is the systematic study...

 and hygienist.
He was born at the historic Pfarrhaus of the village of Bürg, Neuenstadt am Kocher

Neuenstadt am Kocher

Neuenstadt, usually known as Neuenstadt am Kocher is a town in Baden-Württemberg in south-western Germany with 9,600 inhabitants...

, in Württemberg

Württemberg

Württemberg , formerly known as Wirtemberg or Wurtemberg, is an area and a former state in southwestern Germany, including parts of the regions Swabia and Franconia....

. After studying medicine

Medicine

Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

 at Tübingen

Tübingen

Tübingen is a traditional university town in central Baden-Württemberg, Germany. It is situated south of the state capital, Stuttgart, on a ridge between the Neckar and Ammer rivers.-Geography:...

 he became a teacher of zoology

Zoology

Zoology |zoölogy]]), is the branch of biology that relates to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct...

 at Vienna

Vienna

Vienna is the capital and largest city of the Republic of Austria and one of the nine states of Austria. Vienna is Austria's primary city, with a population of about 1.723 million , and is by far the largest city in Austria, as well as its cultural, economic, and political centre...

. In 1868 he was appointed professor of zoology at the academy of Hohenheim

Hohenheim

Stuttgart-Hohenheim is a quarter of Plieningen, one of the 18 outer districts of Stuttgart, the state capital of Baden-Württemberg, Germany...

, and subsequently he became teacher of zoology and anthropology

Anthropology

Anthropology is the study of humanity. It has origins in the humanities, the natural sciences, and the social sciences. The term "anthropology" is from the Greek anthrōpos , "man", understood to mean mankind or humanity, and -logia , "discourse" or "study", and was first used in 1501 by German...

 at Stuttgart

Stuttgart

Stuttgart is the capital of the state of Baden-Württemberg in southern Germany. The sixth-largest city in Germany, Stuttgart has a population of 600,038 while the metropolitan area has a population of 5.3 million ....

 polytechnic and professor of physiology at the veterinary school. In 1884 he abandoned teaching and started practice as a physician in Stuttgart. He wrote various works on biological subjects, including Die Darwinsche Theorie und ihre Stellung zu Moral und Religion (1869), Lehrbuch der allgemeinen Zoologie (1871–1878).

In 1876 he suggested a hypothesis in explanation of heredity

Heredity

Heredity is the passing of traits to offspring . This is the process by which an offspring cell or organism acquires or becomes predisposed to the characteristics of its parent cell or organism. Through heredity, variations exhibited by individuals can accumulate and cause some species to evolve...

, resembling the germplasm

Germplasm

A germplasm is a collection of genetic resources for an organism. For plants, the germplasm may be stored as a seed collection or, for trees, in a nursery.-See also:*Germ plasm, the germ cell determining zone...

 theory subsequently elaborated by August Weismann

August Weismann

Friedrich Leopold August Weismann was a German evolutionary biologist. Ernst Mayr ranked him the second most notable evolutionary theorist of the 19th century, after Charles Darwin...

, to the effect that the germinal protoplasm

Protoplasm

Protoplasm is the living contents of a cell that is surrounded by a plasma membrane. It is a general term of the Cytoplasm . Protoplasm is composed of a mixture of small molecules such as ions, amino acids, monosaccharides and water, and macromolecules such as nucleic acids, proteins, lipids and...

 retains its specific properties from generation to generation, dividing in each reproduction into an ontogenetic portion, out of which the individual is built up, and a phylogenetic portion, which is reserved to form the reproductive material of the mature offspring.

In Die Entdeckung der Seele ("The Discovery of The Soul, 1878) Jäger advanced the first crude version of the pheromone

Pheromone

A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual...

 concept. His postulated skin "anthropines," popularly dubbed "lust compounds," came astoundingly close to reality but the idea was too far ahead of the possibilities of chemistry and the life sciences at this time to be corroborated by experiments.

The system of clothing associated with his name originates from Die Normalkleidung als Gesundheitsschutz ("Standardized Apparel For Health Protection, 1880), wherein he advocated the wearing of rough fabrics such as wool "close to the skin", objecting especially to the use of any kind of plant fibre. The teachings of Jäger inspired the creation of the Jaeger clothing brand

Jaeger (clothing retailer)

Jaeger is a United Kingdom based high-end fashion brand and retailer of menswear and womenswear formed in 1884 by Lewis Tomalin ....

.

He also was a very active entomologist specialising in beetles  particularly Buprestidae and Scarabaeidae

Scarabaeidae

The family Scarabaeidae as currently defined consists of over 30,000 species of beetles worldwide. The species in this large family are often called scarabs or scarab beetles. The classification of this family is fairly unstable, with numerous competing theories, and new proposals appearing quite...

. He wrote with Carl Gustav Calwer

Carl Gustav Calwer

Carl Gustav Calwer was a German entomologist who specialised in Coleoptera....

Käferbuch-Naturgeschichte der Käfer Europas. This very popular work was successively reprinted until 1916. His beetle collection is in Stuttgart Natural History Museum

External links

• DEI ZALF Portrait.