The Kangaroo does not want to catch ‘rheumatism’. Spot this word in stanza 3 and say why it is spelt differently. Why is it in two parts? Why does the second part begin with a capital letter?
Roo-Matiz' is the term. Maintaining the poem's rhyme is spelt differently. It's in two components because it demonstrates that the Kangaroo was a bit reluctant to tell the Duck about his issue, and secondly, he also wanted to highlight his problem.
The term rhoo implies cold and Matiz (matism) implies pain in the joints. When the two words are combined, they give the name of one disease, i.e., joint pain, but if separate, they have two disease names. Thus, the second term in capital is written to indicate two distinct illnesses, one triggered by cold and the other triggered by wetness.