Alexander Onufrievich Kovalevsky (7 November 1840 Dvinsk, Russia - 1901) was a Russian embryologist who studied medicine at the University of Heidelberg and became professor at St Petersburg. He showed that all animals go through a period of gastrulation. Jump to: navigation, search November 7 is the 311th day of the year (312th in leap years) in the Gregorian Calendar, with 54 days remaining. ... 1840 is a leap year starting on Wednesday (link will take you to calendar). ... Daugavpils (Belarusian Дзьвінск Dźvinsk, Russian Двинcк Dvinsk, Lithuanian Daugpilis, German Dünaburg, Polish Dzwinow or Dźwińsk, Yiddish דענענבורג Denenburg), population 115,265 in 2000 census) is the second largest city in Latvia. ... Jump to: navigation, search 1901 was a common year starting on Tuesday (see link for calendar). ... ... The Ruprecht Karl University of Heidelberg (German Ruprecht-Karls-Universität Heidelberg; also known as simply University of Heidelberg) was established in the town of Heidelberg in the Rhineland in 1386. ... Saint Petersburg (Russian: Санкт-Петербу́рг, English transliteration: Sankt-Peterburg), colloquially known as Питер (transliterated Piter), formerly known as Leningrad (Ленингра́д, 1924–1991) and Petrograd (Петрогра́д, 1914–1924), is a city located in Northwestern Russia on the delta of the river Neva at the east end of the Gulf of Finland... 1 - blastula, 2 - gastrula; orange - ectoderm, red - entoderm. ...