As Crutledge says, there is a piece missing from Chapter IV of the book.
However I found in the web a site:
http://www.kobobooks.com/ebook/Dr-Ni...1Yw/page1.html
from which a complete version of the book can be downloaded. The file is made of page images and the missing portion can be found between the 3rd paragraph of page 124 and the 2nd paragraph of page 126.
From this site one can also download a - very poor - epub version. I found that extracting the missing part from the pdf version is faster and probably gives a better text.