Editing 1903 in science (section)

==Physiology and medicine==
* March–April – [[David Bruce (microbiologist)|David Bruce]] identifies the parasitic ''[[Trypanosoma brucei|Trypanosoma]]'' [[protist]] as the source of [[African trypanosomiasis]] ("sleeping sickness").<ref>{{cite journal|last=Duggan|first=A. J.|title=Bruce and the African Trypanosomes|journal=The American Journal of Tropical Medicine and Hygiene|volume=26|issue=5 Pt 2 Suppl|pages=1080–3|year=1977|pmid=20787|url=http://www.ajtmh.org/cgi/pmidlookup?view=long&pmid=20787|doi=10.4269/ajtmh.1977.26.1080|url-access=subscription}}{{Dead link|date=August 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>
* May 10 – [[Antoni Leśniowski]] publishes the first article implicating what will later be known as [[Crohn's disease]], in the [[Poland|Polish]] weekly medical newspaper ''Medycyna''.<ref>{{cite journal|last1=Lichtarowicz|first1=A. M.|last2=Mayberry|first2=J. F.|title=Antoni Lésniowski and his contribution to regional enteritis (Crohn's disease)|journal=[[Journal of the Royal Society of Medicine]]|volume=81|issue=8|pages=468–470|pmid=3047387|date=August 1988|pmc=1291720|doi=10.1177/014107688808100817}}</ref>
* [[Alfred Walter Campbell]] divides the [[cytoarchitecture]] of the human brain into 14 areas.<ref>{{cite journal|last=Campbell|first=A. W.|year=1903|title=Histological studies on cerebral localisation|journal=Proceedings of the Royal Society of London|volume=72|issue=477–486|pages=488–492|doi=10.1098/rspl.1903.0077|s2cid=145403326|url=https://zenodo.org/record/1571278}}</ref>
* [[Ernest Fourneau]] synthesizes and [[patent]]s [[Amylocaine]], the first synthetic [[local anesthetic]], under the name ''Stovaine'' at the [[Pasteur Institute]].<ref>"Stovaïne, anesthésique local". ''Bull. Sc. pharmacolog.'' '''10''' (1904): 141.</ref>
* [[Willem Einthoven]] discovers [[electrocardiography]] (ECG/EKG)
* [[Percy Furnivall]] carries out the first known case of [[cardiac surgery]] in Britain.
* The 12th and final edition of Dr [[Richard von Krafft-Ebing]]'s ''Psychopathia Sexualis: eine Klinisch-Forensische Studie'' ("Sexual Psychopathy: a Clinical-Forensic Study") published during the author's lifetime introduces the term ''paedophilia erotica''.
* Formal opening of the [[Johnston Laboratories]] at the [[University of Liverpool]], [[Liverpool]], England.