This is a PDF of a scan of my 1968 Ph.D. thesis. My understanding is that Proquest (the former University Microfilms), which owns copyright to the distribution of my thesis, allows the author to post a PDF like this on their own website. Many of the results and arguments in my 1968 Ph.D. thesis were later published in my 1973 paper in Systematic Zoology and in my 1973 paper in American Journal of Human Genetics. The argument in the thesis about ML estimation of a phylogeny with Brownian Motion characters proceeded in blissful ignorance of the issue of the Jacobian of the transformation of the tree. That issue was taken into account in the 1973 AJHG paper, where it was shown that, fortunately, the Jacobian in this case is 1. Here is a link to the PDF of the thesis.