Journal of Morphology (Volume 2, No. 1) (Paperback)

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: THE SEAT OF FORMATIVE AND REGENERATIVE ENERGY. C O. WHITMAN. The question as to the role of the cytoplasm, presents itself under two forms: 1. Is the cytoplasm a passive body, moving only as it is acted upon by external forces, or in response to influences emanating from the nucleus ? 2. Or does it behave rather like an organized body, endowed with subtle powers of its own, and capable of automatic as well as responsive action ? There is a strong tendency at the present time to refer all kinetic changes in the cytoplasm to the agency of the nucleus, and to ascribe to the former the passive role of a nutritive substance. The kinetic phenomena of the egg during maturation and impregnation have already been considered in their bearing on this important question.1 A number of decisive proofs of pure nuclear action were pointed out, and at the same time an attempt was made to support the opinion that the cytoplasm is capable of automatic as well as responsive action. The present paper is chiefly devoted to the consideration of phenomena displayed in the cytoplasm, and to the discussion of the question, whether the regenerative and formative power of the cell resides in the nucleus or in the cytoplasm, or in both taken as a highly complex physiological unit. The Doctrine of Isotropy. ? Pfliiger's interesting experiments2 with the amphibian egg to determine the influence of gravitation upon the direction of cleavage-planes, led him to conclude that the entire egg is " isotropic." In other words, to quote from theauthor, " the fertilized egg possesses absolutely no essential relation to the later organization of the animal, no more than a snow- flake stands in any essential relation to the size and form of the avalanche which under certain conditions develops from it....