1.as 是定语从句 as he really needed into the jungle 中的关系代词,它等同并代替先行词 men and things,在从句中充当needed的宾语.
即：as he really needed into the jungle
= he really needed (as) into the jungle
= he really needed (such men and things) into the jungle
2.语法规定：如果先行词被such,the same,as 或 so等修饰时,则定语从句的关系代词一般使用as,以构成 such...as...,the same...as...,as...as...,such...as...的固定结构.