Hans Christian Gram

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Hans Christian Gram
Hans Christian Gram portrait by Hansen & Weller.jpg
Hans Christian Gram by Hansen & Weller
Hans Christian Joachim Gram

(1853-09-13)13 September 1853
Copenhagen, Denmark
Died14 November 1938(1938-11-14) (aged 85)
Copenhagen, Denmark
Known forInventing the Gram stain
Scientific career
Doctoral advisorJapetus Steenstrup

Hans Christian Joachim Gram (13 September 1853 – 14 November 1938) was a Danish bacteriologist noted for his development of the Gram stain, still a standard technique to classify bacteria and make them more visible under a microscope.

Early life and education[edit]

Gram was the son of Frederik Terkel Julius Gram, a professor of jurisprudence, and Louise Christiane Roulund.

He studied at the University of Copenhagen, and was an assistant in botany to the zoologist Japetus Steenstrup. His study of plants introduced him to the fundamentals of pharmacology and the use of the microscope.

Gram entered medical school in 1878 and graduated in 1883. He travelled throughout Europe between 1878 and 1885.


Gram stain[edit]

In Berlin, in 1884, Gram developed a method for distinguishing between two major classes of bacteria.[1] This technique, the Gram stain, continues to be a standard procedure in medical microbiology. This work gained Gram an international reputation. The stain later played a major role in classifying bacteria. Gram was a modest man, and in his initial publication he remarked, "I have therefore published the method, although I am aware that as yet it is very defective and imperfect; but it is hoped that also in the hands of other investigators it will turn out to be useful."

A Gram stain is made using a primary stain of crystal violet and a counterstain of safranin. Bacteria that turn purple when stained are called 'Gram-positive', while those that turn red when counterstained are called 'Gram-negative'.

Other work[edit]

Gram's initial work concerned the study of red blood cells in men. He was among the first to recognise that macrocytes were characteristic of pernicious anaemia.

In 1891, Gram taught pharmacology, and later that year was appointed professor at the University of Copenhagen. In 1900, he resigned his chair in pharmacology to become professor of medicine.[2] As a professor, he published four volumes of clinical lectures which became widely used in Denmark. He retired from the University of Copenhagen in 1923, and died in 1938.[2]

Popular recognition[edit]

On 13 September 2019, Google commemorated the anniversary of his birth with a Doodle for Canada, Peru, Argentina, Australia, New Zealand, Israel, India and some European countries.[3][4]


  1. ^ Gram, H.C. (1884). "Über die isolierte Färbung der Schizomyceten in Schnitt- und Trockenpräparaten". Fortschritte der Medizin (in German). 2: 185–189.
    An English translation is in Brock, T.D. (1999). Milestones in Microbiology 1546–1940 (2 ed.). ASM Press. pp. 215–218. ISBN 1-55581-142-6.
    A translation is also at Brock, T.D. "Pioneers in Medical Laboratory Science: Christian Gram 1884". Hoslink. Retrieved 27 July 2010.
  2. ^ a b Jay Hardy. "Gram's Serendipitous Stain" (PDF). Retrieved 13 March 2016.
  3. ^ "Hans Christian Gram's 166th Birthday". Google.com. 13 September 2019. Retrieved 13 September 2019.
  4. ^ Michallon, Clémence (13 September 2019). "Who was Hans Christian Gram and what did the groundbreaking scientist discover?". Independent UK. Retrieved 13 September 2019.

External links[edit]