DEPARTMENT OF EMBRYOLOGY. 119 



even when generations of cells have taken place in a simple Locke's 

 solution. 



Dr. G. W. Corner has investigated the differences between the cor- 

 pora lutea at the different periods of their evolution and has attempted 

 to obtain criteria for the determination of the age of these bodies. In 

 the corpus luteum of the sow he has described three kinds of cells — the 

 lutein cells and the additional cells of the corpus luteum, types 1 and 2. 

 His study shows, in the different ages, the variations of these two latter 

 types of cells and the cytological changes of the lutein cells, in their 

 canalicular apparatus, in their granules (especially in the quantity of 

 fat granules), in the colorabihty of the nucleus, and in the relative 

 quantity of exoplasm and endoplasm. Certain stages of the evolution 

 of the corpus luteum show also an increase in the connective tissue. 

 All these changes occur with perfect constancy, and Corner has thus 

 been enabled to establish a regular series. The corpus luteum of 

 pregnancy differs from the corpus luteum of ovulation in the greater 

 regularity of its structure and its smaller content of fat. He shows 

 further that in the sow during pregnancy no other Graafian follicle 

 becomes mature and that the external migration of the egg is a frequent 

 and normal phenomenon. 



Certain features in the development of the nervous system have been 

 the subject of investigation during the yesir. Among these are included 

 a study of the sensory nerve-endings in muscle, experimental studies 

 on the membranous labyrinth, experimental degenerations of the spinal 

 cord, a volumetric study of the development of the parts of the brain, 

 and a histological study of the temporary cavities that are found in 

 embrj'onic brain-tissue. 



Mr. A. C. Sutton has added to our literature the first complete 

 description of the embryological histoiy of the sensory nerve-endings in 

 muscle and accompanies it by illustrations showing the principal stages 

 in their development. The intricate structure of the full-grown neuro- 

 muscular spindles makes the study of their simpler forms particularly 

 valuable. Mr. Sutton's investigations were carried out on the extrinsic 

 eye-muscles of embryo pigs in which the sensory nerves and their 

 endings were studied by staining i7itra vitam with methylene blue. 

 The earliest stage in which he was able to distinguish them was in 

 embryos 12 mm. long. From this point they were followed up to pigs 

 200 mm. long, where they practically have their adult form. 



He finds that the axones (embryo 12 mm.) grow out from the cells of 

 the sensory ganglia and terminate in the premuscle mass in bulbous 

 ends from which delicate fibrils extend a little further and lie loosely 

 among the rounded myoblasts, to which they subsequently become 

 attached by the formation of a neuro-fibrillar net. With the develop- 

 ment of the myoblast into the adult muscle fiber this net becomes more 

 and more complex, and at the same time an intermediary structure is 



