Thomas Hunt Morgan
Thomas Hunt Morgan (1866-1945) received the Nobel Prize in Medicine or Physiology in 1933 for his discoveries concerning the role chromosomes play in heredity.
At the beginning of his career, however, Morgan spent considerable time and effort on the study of embryogenesis and regeneration, and published several important articles and books on these subjects. Of relevance to us is his 1901 book appropriately entitled "Regeneration". The work and ideas presented in this book remain relevant to the modern study of regeneration, and many of the incisive questions postulated in this work remain unanswered to this day.
However, Morgan eventually abandoned the study of regeneration since, in his own words, he felt that "we will never understand the phenomena of development and regeneration" (Berrill, N. J. "The pleasure and practice of biology" Can. J. Zool. 61: 947-951, 1983).

Below is an illustration made by Morgan for his book on regeneration showing the variety of ways planarians go about regenerating themselves. The original caption reads:
"Fig. 4.- A-E Planaria maculata. A. Normal worm. B, B1. Regeneration of anterior half. C, C1. Regeneration of posterior half. D. Cross piece of worm. D1, D2, D3, D4. Regeneration of same. E. Old head. E1, E2, E3. Regeneration of same. F. P. lugubris. Old head cut off just behind the eyes. F1. Regeneration of new head on posterior end of same."