From: eensio     Dec 29, 2018

Interesting is in the beginning of measure 10 is the "pseudo"octave passage. And tenors jump afterwards.
Thank you about this work for chorales of Bach!

From: SDG     Dec 29, 2018

I don't know if it is a pseudo octave (end of 9?) passage (https://en.wikipedia.org/wiki/Pseudo-octave ). Looks like a full octave to me (tenor-bass). Thank you!

From: BSG     Dec 29, 2018

What he means is that this is "keyboard bad", i.e., if you play m 9 at the keyboard, parallel octaves A-G between the fingers will result (the 3rd and 4th beats). But it's not for the keyboard! - the concerned parts have no faulty parallels. This happens often in Bach, and is not often discussed and has no real name (other than "parallel avoided by voice crossing"), but the necessary condition is that the motions of the parts make sense individually. I don't see it in m .10 (his comment changed).