Answer

‘the loaf of brains’ makes it seem like a loaf of bread. Bread is essential for food and the brain is essential for living and surviving. Perhaps he sees a similarity in the way they look.

‘the web of nerves’ makes it seem like a spider’s web, which shows the nerves are very fine strands, like tiny pieces of cotton and there are lots of them. The idea of a web means they are interconnected and very complex.

‘blood – a gallon exactly of bilberry soup’ gives a sense of the colour (red) and thickness of our blood as it would be like a soup. The taste is perhaps similar to bilberry. There is a sense of the richness of our blood.

‘the chassis or cage or cathedral of bone’ is a complex metaphor for the bone structure which is like the chassis of a car (the frame work of the engine) and the skeleton is likened to a cathedral, a place of worship or, indeed, something to worship as it is such a marvellous creation, or it is a cage to keep in all the various elements of the body.