The word ‘rheumatism’ is spelt differently and is in two parts so that it can rhyme with ‘kangaroo’ in the following line. As a result of splitting the word into two and changing its spelling, ‘Roo’ rhymes with ‘kangaroo’. The second part ‘Matiz’ begins with a capital letter because it is the first word of the line. In a poem, every line begins with a capital letter even if it is in continuation with the previous line. Hence, this has been done in order to enhance the poetic effect of the lines.
