180 



SCIENCE. 



[N. S. Vol. XI. No. 266. 



sudden blow on a muscle producing con- 

 traction is the same as the normal nerve 

 impulse received through the nerve. The 

 result is more or less the same because the 

 same mechanism is set to work in the 

 muscle or in the egg, but it would be mis- 

 leading to infer that, therefore, the stimuli 

 are themselves alike because they produce 

 nearly similar results. 



Reissner's fibre in the canalis centralis of ver- 

 tebrates. Porter Edward Sargent. 

 Eeissner in 1860 described in Petromyzon 

 a cylindrical rod or fibre lying in the canalis 

 centralis. His discovery was confirmed 

 three years later by Kutschin who named 

 it Reissner's fibre. Its presence has since 

 been noted in a considerable number of 

 fishes by three other investigators. By 

 these it has been generally considered an 

 artifact formed by the coagulation of the 

 cerebro-spinal fluid. 



Researches carried on during the past 

 year has proved it to be a continuous fibre 

 extending through the whole length of the 

 canalis centralis and into the brain ven- 

 tricles, and constituting an integral part of 

 the central nervous system of all verte- 

 brates. 



As its posterior end Reissner's fibre gives 

 off fine processes which pass peripherally 

 between the epithelial cells forming the 

 walls of the canal into the nervous sub- 

 stances of the cord. Anteriorly it extends 

 forward through the fourth ventricle to the 

 anterior region of the third ventricle, where 

 after dividing several times each, division 

 enters the torus longitudinalis posterior 

 and ventral to the posterior commissure. 

 Within the torus the divisions of Reissner's 

 fibre divide many times, becoming event- 

 ually distributed to the ectal region of the 

 optic lobes. In cross section the fibre 

 shows a thin myelin sheath, and the central 

 portion has a punctate appearance. Stud- 

 niscka's recent deductions as to the nature 



of the fibre are shown to be incorrect and 

 drawn from insufficient data. 



The development in Amia and some other 

 Teleosts has been worked out. Shortly 

 after hatching some of the neuroplasts in 

 the anterior portion of the optic tectum be- 

 come differentiated, increasing greatly in 

 size. By the second day after hatching 

 these twenty to thirty cells send out pro- 

 cesses which grow downward, penetrate into 

 the third ventricle and growing posteriorly, 

 coalesce to form Reissner's fibre. By the 

 end of the second day this has grown 

 posteriorly through the aqueduct of Sylvius 

 and by the third day through the whole 

 length of the canalis centralis. 



The following papers were read by title : 



' Ingestion of follicle cells by the ovarian 

 ovum of the rat,' by Maynard M. Metcalf. 



' Newly found parallels between dino- 

 saurs and birds,' by Henry F. Osborn. 



' Terminal nerve cells in the skin and 

 fate of the lateral line organs in Amphibia,' 

 by C. L. Herrick. 



' The nervous apparatus in the saccus 

 vasculosus in Acipenser,' by J. B. Johnston. 



' The giant cells in the spinal cord of 

 Catostomus,' by J. B. Johnston. 



' A suggestion as to the meaning of the 

 periodical degeneration which occurs in 

 some compound ascidians,' by Maynard M. 

 Metcalf. 



' New observations upon the structure of 

 Octonemus,' by Maynard M. Metcalf. 



'New England species of Giossophonia,' 

 by W. E. Castle. 



' Notes on the tracheal system in Neu- 

 roptera,' by G. C. Scott. 



' Demonstration of photomicrographs in 

 cytology,' by Katharine Foot. 



' A case of regeneration of the end of a 

 human finger,' by W. E. Ritter. 



' On the multiplication of arms in the 

 twenty-rayed starfish Pycnopodium helian- 

 thoides,' by W. E. Ritter. 



