▁In ▁ 1 8 5 2 ▁H . F . ▁St ann ius ▁experiment ed ▁on ▁the ▁heart . ▁By ▁t ying ▁a ▁lig ature ▁as ▁a ▁con str iction ▁between ▁the ▁sin us ▁ven os us ▁and ▁the ▁at rium ▁in ▁the ▁f rog ▁and ▁also ▁one ▁around ▁the ▁at ri ov ent ric ular ▁gro ove , ▁St ann ius ▁was ▁able ▁to ▁demonstrate ▁that ▁the ▁mus cle ▁t issues ▁of ▁the ▁at ria ▁and ▁vent ric les ▁have ▁independent ▁and ▁sp ont aneous ▁rh yth ms . ▁His ▁observations ▁also ▁indicated ▁that ▁the ▁sin us ▁is ▁the ▁pac em aker ▁of ▁the ▁heart be at . ▁ ▁References ▁ ▁Category : Bi ology ▁experiments <0x0A> </s> ▁Clar ence ▁Smith ▁was ▁a ▁U . S . ▁s occer ▁player ▁who ▁played ▁the ▁first ▁two ▁U . S . ▁national ▁team ▁games ▁in ▁ 1 9 1 6 . ▁ ▁Smith ▁earned ▁two ▁caps ▁with ▁the ▁national ▁team ▁in ▁ 1 9 1 6 . ▁ ▁In ▁the ▁first ▁official ▁U . S . ▁national ▁team ▁game , ▁the ▁U . S . ▁defeated ▁Sweden ▁on ▁August ▁ 2 0 , ▁ 1 9 1 6 . ▁ ▁On ▁September ▁ 3 , ▁ 1 9 1 6 , ▁Smith ▁and ▁his ▁team ▁m ates ▁tied ▁Norway ▁before ▁returning ▁to ▁the ▁U . S . ▁ ▁At ▁the ▁time , ▁he ▁played ▁for ▁Bab cock ▁& ▁Wil co x ▁F . C . ▁in ▁the ▁National ▁Association ▁Football ▁League . ▁ ▁References