Induction of cell differentiation: III. A quantitative approach in the analysis of induction

A mathematical analysis of enzyme induction is given, assuming three different action mechanisms of the inducer: formation of a specific template, action as a derepressor, and incorporation into the template. The formation of vertebral cartilage in explanted chick somites seems to be best represented by the model of incorporation into the template.     

The evidence for a meiotic process in the euglenineae

Summary Cells of Hyalophacus ocellatus are described which contain either a nuclear figure consisting of a double complement of highly condensed chromosomes arranged in pairs in the anterior half of the cell, or a huge posteriorly-placed nucleus consisting of long granular chromosomes which also show signs of pairing. These nuclear figures are quite unlike interphase nuclei or stages in mitosis and are thought to be stages in euglenoid meiosis.No evidence has been obtained for a sexual fusion of gametes or cells. Previous accounts of sexuality and autogamy in the Euglenineae are historically reviewed and critically discussed relative to the present observations.This paper is dedicated to Professor Dr. E. G. Pringsheim on the occasion of his 80th birthday, with gratitude both for his untiring advice on my research and for his friendship.     

Acromegaly: A Review of 100 Cases

Clinical and pathological findings in 100 cases of acromegaly were reviewed. Great individual variation in manifestations of the disease was apparent. The chronic course was evidenced by 30 patients presenting symptoms unrelated to acromegaly. Headache, visual disturbances, arthritis and elevated blood pressure were common. The incidence of diabetes mellitus, thyroid and adrenal dysfunction was similar to that reported in other series. Gonadal disturbances were frequent. Two patients had galactorrhea and two had hyperparathyroidism. Radiologically, pituitary fossae were normal in 24. Pituitary histology in 29 cases revealed four eosinophilic adenomas, but most were mixed eosinophilic-chromophobic. Fifty-two patients received radiation therapy. Rhinorrhea and optic nerve fibrosis were seen in this group. Twenty-four patients were operated upon, with no operative deaths since 1945 and no morbidity since 1952. Visual failure was the clearest indication for surgery. Treatment will be difficult to evaluate until an index of growth hormone secretion is generally available.