  Interference effects between Berry phase factors in spin tunneling systems
have been discussed in recent Letters by Loss, DiVincenzo and Grinstein and von
Delft and Henley. This Comment points out that Berry phases in spin tunneling
are important in another interesting case: the two dimensional doped
antiferromagnet. I show that the dispersion of a single hole in the t-J model
changes sign as $e^{2\pi s}$ where $s$ is the size of the spins. This provides
an interpretation of the numerical results for the $s=\half$ model, and a
prediction for other spin sizes.
