Possible Clues:

• Insubstantial small muscle lacks oxygen
• Ghostly: just like the light coming from a prism?
• Ghostly second muscle wanting nothing
• Ghastly plaster spread over cottage initially
• Singular description of chest, omitting nothing regarding range of colours
• Like shade from colour ranges with finish of eggshell
• Start to suffer in the chest when dropping round, appearing ghostly
• Insubstantial small muscle, one failing in test
• Carl's pet cuckoo is out of this world
• Phantomlike