▁was ▁also ▁active ▁in ▁bi ology , ▁particularly ▁in ▁classification ▁of ▁organ isms ▁and ▁min er als . ▁His ▁bi ological ▁work ▁was ▁influenced ▁by ▁Lin na eus . ▁Lehr b egr iff ▁der ▁Natur geschichte ▁Zum ▁ersten ▁Unter rich te , ▁his ▁most ▁extensive ▁publication ▁in ▁bi ology , ▁was ▁on ▁system atic ▁classification ▁of ▁plants , ▁animals , ▁and ▁min er als , ▁as ▁well ▁as ▁the ▁element al ▁subst ances ▁ ether , ▁fire , ▁air , ▁water ▁and ▁earth . ▁ ▁References ▁ ▁External ▁links ▁▁ ▁K D G ▁W itten berg : ▁Prof . ▁Dr . ▁Joh . ▁Daniel ▁Tit ius ▁Pl ants ▁and ▁Plan ets : ▁The ▁Law ▁of ▁Tit ius - B ode ▁explained ▁by ▁H . J . R . ▁P erd ijk ▁▁▁ ▁Category : 1 7 2 9 ▁birth s ▁Category : 1 7 9 6 ▁death s ▁Category : Pe ople ▁from ▁Ch oj nice ▁Category : G erman ▁astronom ers ▁Category : Pe ople ▁from ▁Royal ▁Pr uss ia ▁Category : G erman ▁phys ic ists ▁Category : G erman ▁bi olog ists <0x0A> </s> ▁The ▁Ar bor et um ▁at ▁P enn ▁State ▁Be hr end ▁( 7 2 5 ▁acres ) ▁is ▁an ▁ar bor et um ▁located ▁across ▁the ▁campus ▁of ▁P enn ▁State ▁Er ie , ▁The ▁Be hr end ▁College , ▁in ▁Er ie , ▁Pennsylvania . ▁It ▁is ▁open ▁daily ▁without ▁charge . ▁ ▁The ▁ar bor et um ▁was ▁dedicated ▁in ▁ 2 0