Final answer:
Mark Inglis lost the tips of several fingers to frostbite. Extreme cold can cause substantial damage, such as loss of skin, nails, and even digits or limbs due to frostbite.
Step-by-step explanation:
The passages provided describe the severe effects of frostbite experienced by individuals exposed to extreme cold without adequate protection. Specifically, Mark Inglis lost the tips of several fingers to frostbite. In the case of fictional incidents similar to those experienced by characters created by Jack London, like the man in 'To Build a Fire,' the loss or damage can be much more significant.
Frostbite can lead to the loss of skin, nails, and in severe cases, entire digits or limbs, as indicated in the provided texts. The detailed situations depict the dangers that extreme cold poses to the extremities, such as fingers and toes, but also to the nose, cheeks, and other exposed skin.