A contribution to the cell-physiologic analysis of growth and morphogenesis in fern prothallia

Summary

The cell physiologic investigations on the analysis of growth and morphogenesis of the prothallia ofDryopteris parasitica brought the following results:

• 1. Within a normally developed prothallium there are pronounced gradients. These gradients are to be regarded first of all as gradients of growth. For characterizing them the data for three special states of development given in table p. 27 may be used.

• 2. With prothallia grown under changed conditions of light reacting to this change with a form different from the normal one (Fig. 3), we could show that morphologically equivalent cell-filaments possess also cell physiologically equivalent gradients while morphologically unequivalent cell-filaments show also cell physiologically unequivalent gradients.

• 3. On the basis on the one hand of the described investigations and on the other hand of the results on growth in fern prothallia cited in the bibliography, the opinion is pointed out that in the process of morphogenesis there is a correlation between a cytologic and a histogenic tendency of development. A manifestation of the cytologic tendency of development is the formation of cellular gradients, while a manifestation of the histogenic tendency is to be regarded as the formation of the gradients within the whole prothallium.