Claude Bernard (1813-1878)
French physiologist

One of the founders of experimental physiology and one of the first to recognize the importance of the "internal environment''.  Bernard must have had a troubled domestic life: his work involved vivisection (the dissection of live animals) and his wife and daughters became active-antivivisectionists. 

Adpated from cscs.umich.edu/~crshalizi/notebooks/bernard.html and www.whonamedit.com/doctor.cfm/846.html