Histogram function in R - breaks argument not working

I like to create histogram objects per row with defined breaks:

Hist <- list()
for (i in 1:10) { 
   Hist[[i]] <- hist(data[i,],breaks=25)
}

But there is an indifference between my requirement of breaks and the number of breaks which is in the output. And also the number of breaks within the histograms is different.

Is there a reason for that?