Appointed as personal secretary to Lithuanian linguist Kazimieras Jaunius he showed great interest in the subject, and during the period 1905-12 studied at Saint Petersburg State University.

After that, he continued his work on Indo-European language under the supervision of Jan Niecisław Baudouin de Courtenay.

From these he was able to determine that the homeland of the Lithuanians and other Baltic peoples up to the 6th to 9th centuries CE had been just north of Ukraine in the area around the Pripyat River.

In addition, he studied the chronological sequence of Slavic loanwords in the Baltic languages.

He also carried out a linguistic reconstruction of the names of the early princes of the Grand Duchy of Lithuania and refuted the theories of their Slavic origin.