there is the feeling ( gerund ) of part of one's own body externalised, [thus/thereby] prolonging [ participle ]its life beyond the death of the rest of one's body, and possibly in its turn externalising [ participle ] part of itself in the same fashion, and so securing [ participle] the immortality of the germ-plasm. germ-plasm' would be non-finite clauses acting as adverbials.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.