University of Tübingen
What was the name of the employer Carl Correns work for from 1892 to 1909?
Carl Correns Carl Erich Correns ( 19 September 1864 – 14 February 1933 ) was a German botanist and geneticist , who is notable primarily for his independent discovery of the principles of heredity , which he achieved simultaneously but independently of the botanist Hugo de Vries and for his rediscovery of Gregor Mendels earlier paper on that subject . Correns was a student of Karl Nägeli , a renowned botanist with whom Mendel corresponded about his work with peas , and who subsequently engaged in a long exchange of letters concerning reproducibility of the results in another species ( Hieracium ) . Because of the special properties of Hieracium , those experiments failed and Mendel dropped his studies on the subject . Early life and education . Carl Correns was born September 1864 in Munich . Orphaned at an early age , he was raised by an aunt in Switzerland . He entered the University of Munich in 1885 . While there , he was encouraged to study botany by Karl Nägeli . After completing his thesis , Correns became a tutor at the University of Tübingen and in 1913 he became the first director of the newly founded Kaiser Wilhelm Institute for Biology in Berlin-Dahlem . He married a niece of Karl Nägeli , Elisabeth Widmer . Key experiments and findings . Carl Correns conducted much of the foundational work for the field of genetics at the turn of the 20th century . He rediscovered and independently verified the work of Mendel in a separate model organism . He also discovered cytoplasmic inheritance , an important extension of Mendels theories , which demonstrated the existence of extra-chromosomal factors on phenotype . Some of his unpublished work and most of his lab books were destroyed in the Berlin bombings of 1945 . Rediscovery of Mendel . In 1892 , while at the University of Tübingen , Correns began to experiment with trait inheritance in plants . Correns published his first paper on 25 January 1900 , which cited both Charles Darwin and Mendel , recognising the relevance of genetics to Darwins ideas . In Correns paper , G . Mendels Law Concerning the Behavior of the Progeny of Racial Hybrids , he restated Mendels results as the law of segregation and introduced a new law of independent assortment . Cytoplasmic inheritance . After rediscovering Mendels laws of heredity , which can be explained with chromosomal inheritance , he undertook experiments with the four oclock plant Mirabilis jalapa to investigate apparent counterexamples to Mendels laws in the heredity of variegated ( green and white mottled ) leaf color . Correns found that , while Mendelian traits behave independently of the sex of the source parent , leaf color depended greatly on which parent had which trait . For instance , pollinating an ovule from a white branch with pollen from another white area resulted in white progeny , the predicted result for a recessive gene . Green pollen used on a green stigma resulted in all green progeny , the expected result for a dominant gene . However , if green pollen fertilized a white stigma , the progeny were white , but if the sexes of the donors were reversed ( white pollen on a green stigma ) , the progeny were green . This non-mendelian inheritance pattern was later traced to a gene named iojap which codes for a small protein required for proper assembly of the chloroplast ribosome . Even though iojap assorts according to Mendels rules , if the mother is homozygous recessive , then the protein is not produced , the chloroplast ribosomes fail to form , and the plasmid becomes non-functional because the ribosomes cannot be imported into the organelle . The progeny could have functional copies of iojap , but since the chloroplasts come exclusively from the mother in most angiosperms , they would have been inactivated in the previous generation , and so will give white plants . Conversely , if a white father is paired with a green mother with functional chloroplasts , the progeny will only inherit functional chloroplasts , and will thus be green . In his 1909 paper , he established variegated leaf color as the first conclusive example of cytoplasmic inheritance . External links . - Article relating the work of Gregor Mendel