vital fluid

How do these animals obtain their sustenance, and what changes can they produce upon the vital fluid of the body?

Only a very delicate membrane separates the vital fluid of the mother from that of the infant in her womb.

I was never more struck with this, than in the case of Duncan, where the blood was more like thick brownish ink than vital fluid.

Now the redness of the blood is owing to myriads of minute objects in which the colour of the vital fluid resides.

Organizations which have not been exhausted by powerful emotions often have a vast amount of the vital fluid at their service.