TABLE OF CONTENTS. II. Comparative regeneration.... III. Regeneration in higher mammals. V. Survival and proliferation of animal tissues outside the body. VI. Factors responsible for cell proliferation and regeneration....... Page. 5. Culture of liver, new connective-tissue cells-growth 3 days........... 6. Culture of liver, type of new connective-tissue cells-growth 3 days... 7. Culture of liver, new glandular cell proliferation-growth 3 days............ 14. Culture of hypophysis, anterior lobe-growth 24 hours.. 15. Culture of bone marrow-growth 7 days..... 16. Culture of bone marrow-growth 7 days, high power... 17. Culture of spleen, connective-tissue cell-growth 24 hours... 23. Culture of spinal cord, bipolar and multipolar cells-growth 6 days... 24. Culture of spinal cord, undifferentiated cell-growth 6 days..... 25 Culture of spinal cord, showing all types of new cell growths... 64 TISSUE PROLIFERATION IN PLASMA CULTURE MEDIUM.' By JOHN SUNdwall, Special Expert, Hygienic Laboratory, United States Public Health and Marine Hospital Service, Washington, D. C. PART I. I. INTRODUCTION. Recent investigations initiated by Harrison, and later modified and extended by Burrows, Carrel, Hanes, Lewis, and others, on the growth of both normal and abnormal tissues, in plasma and other media, has apparently opened up a new and extensive field of biological research. In order to ascertain to some degree at least the value of the application of this method to some of the various problems of morphology, pathology, bacteriology, and kindred sciences directly confronting us, investigation was begun in the Hygienic Laboratory. In the beginning it was found highly desirable to determine, first, the proliferating powers of normal tissue by this media incubation method and then compare these new growths with similar proliferations and regenerations which take place within the body under certain conditions and which have already been fairly well determined. This bulletin is concerned chiefly with a discussion of the results obtained in this laboratory on the manner, degree, and morphology of normal tissue proliferation in plasma medium. Later will appear the results of studies upon abnormal tissue growths. For convenience of discussion the subject matter is subdivided into the following: Part I: 1. Comparative regeneration. 2. Regeneration of various tissues in higher mammals. 3. Metaplasia. 4. Survival and growth of tissues outside of the animal organism. Part II: 1. Technique. 2. Proliferation of various tissues in plasma culture medium. Part III: Discussion of results and conclusions. 1 Manuscript submitted for publication Jan. 18, 1912. II. COMPARATIVE REGENERATION. That the various tissues making up animal organisms have powers of regeneration has been known for a long time. As early as 1740, Abbé Trembley made observations on the regenerative properties of Hydra viridis. Parts of this organism would regrow into new and complete Hydra. A split head would produce two complete heads. Abbé Spallanzi, 1768, likewise made observations on the regeneration of the earthworm. Shaw, 1790; Drapernauld-Dalyell, 1814; Johnson, 1822, 1825; Dugès, 1828; and Farrady, 1832, contributed further to our knowledge of the regenerative capacities of the simpler animal life forms, especially the planarians. Later, the relation of the nucleus to the regenerative capacity of the cell was established by Gruber,1 Nussbaum, and others. Portions of the cell not possessing nuclear elements could not regenerate. 6 3 4 2 Randolph made additional observations on regeneration in planarians, and Morgan, following up the work of Randolph, studied the relations between the parts removed and the new organisms developing from such parts. Pieces were taken from various portions of the body and the degree of regeneration of these parts were observed. Flexner also adds to our knowledge of comparative regeneration. Loeb described certain phenomena in Campanulariæ by which pollyps, after contact with solid bodies, are transformed and creep into the stem, new stolons developing. Attention is called to the fact that "the process of growth is identical with the process of progressive motion of a protoplasmic mass." He also established geotropism in tubularians by cutting off the head and feet ends of the organism, then inverting it. A head generates at the feet end, while feet develop at the end originally possessing the head. 8 The regenerative capacities of the various orders of vertebrates are briefly discussed by Morgan. Fishes and salamanders have excellent powers of regeneration. New legs, tails, and eyes develop quickly when these parts are destroyed in certain amphibians, such as the salamander, newt, and tadpole. Regeneration in an adult frog, however, is a much slower process. Among reptiles, the lizard can generate anew a tail but no legs. And there are still greater limitations in birds, for here the beak only can regenerate. In mammals this property of complete regeneration of an organ is entirely lost, for neither tail, legs, nor other external structures grow again where once removed. Morgan is of the opinion that— (a) The power of regeneration is closely related to the power of growth inherent in the protoplasm. |