Name the Biologist - "week" 16

Sorry for the tardiness. A busy couple of weekends has prevented me from doing the feature justice. Luckily "anonymous" is good at getting these right so hopefully people weren't pulling their hair out trying to discover the answer.

This one should be realtively easy. I will try and make the next one more of a challenge.
As for last week, from top to bottom we have Theodor Boveri, Walter Sutton and Walther Flemming. Boveri and Sutton are famous for working out that the chromosomes are the carriers of genetic material. this is one of those things we take for granted now but it was a major breakthrough for linking genetic theory with molecular biology. Case in point is Walther Flemming, the scientist who first described chromosomes but because he was unaware (of the then lost) work by Mendel never quite realised just how important his observations were.