There's a mumble from Inigo - really not something anyone could understand, since he's talking around the finger he's still got in his mouth, despite Senku's warning. But he's probably trying to say something along the lines of 'but I always do this'.. then again, much more basic hygienic rules are already lose on Inigo, so maybe this is just a lost cause.

At least he seems content with how it stops bleeding a moment later, and he leans over to take a look into the microscope as well the moment Senku steps away.

"How can you see that?"

The white blood cells thing, he means.. Are they literally white? Are these more of the things they're made of? This is all so confusing for a simple medieval boy.