Comment on ``Magnetoresistance Anomalies in Antiferromagnetic   YBa$_2$Cu$_3$O$_{6+x}$: Fingerprints of Charged Stripes''
  In a recent Letter Ando et al (cond-mat/9905071) discovered an anomalous magnetoresistance(MR) in hole doped antiferromagnetic YBa$_2$Cu$_3$O$_{6+x}$, which they attributed to charged stripes, i.e., to segregation of holes into lines. In this Comment we show that the experiments, albeit being interesting, do not prove the existence of stripes. In our view the anomalous behavior is due to an (a,b) plane anisotropy of the resistivity in the bulk and to a magnetic field dependent antiferromagnetic (AF) domain structure. It is unlikely that domain walls are charged stripes. 
Andras Janossy, Ferenc Simon, and Titusz Feher