1. Effects of L-tryptophan on morphogenesis and growth in the early chick blastoderm

   • Hadar Emanuelsson
   • Kjell Palén

   OriginalPaper Pages: 1 - 17

2. Comparison of lipids of sea urchin egg ghosts prepared before and after fertilization

   • Mary Lee Barber
   • James F. Mead

   OriginalPaper Pages: 19 - 27

3. The effect of puromycin on the early cleavage cycles and morphogenesis of the pond snailLymnaea stagnalis

   • Elida K. Boon-Niermeijer

   OriginalPaper Pages: 29 - 40

4. An experimental study of the life-cycle of the fresh-water spongeEphydatia fluvitilis in its natural surroundings

   • G. Van de Vyver
   • Ph. Willenz

   OriginalPaper Pages: 41 - 52

5. Interpersonale Differenzierung des Enzymaktivitäts-Musters bei dem polymorphen HydroidenHydractinia echinata

   • Günther May
   • Werner A. Müller

   OriginalPaper Pages: 53 - 59

6. Recruitment of epidermal cells by the developing eye onOncopeltus (Hemiptera)

   • S. M. Green
   • P. A. Lawrence

   OriginalPaper Pages: 61 - 65

7. Differentiation in the mouse morulae

   • Luis Izquierdo
   • Maria Elena Ortiz

   OriginalPaper Pages: 67 - 74

8. Ultrastructural evidence for the absence of premelanosomes in eggs of the albino mutant (a^p) ofXenopus laevis

   • John G. Bluemink
   • Olga A. Hoperskaya

   Short Communication Pages: 75 - 79