424 



SCIENCE 



[N. S. Vol. XXV. No. 637 



tration it has been shown by Hirsch that the 

 blood remains arterial even after the respira- 

 tory movements have been inhibited by curare. 

 When the cervical spinal cord is stimulated, 

 and especially when it is cut, the respiratory 

 movements are very considerably interfered 

 with so that a partial asphyxia is produced 

 which may be the cause of the hyperglycemia. 



The fact that stimulation of the cervical 

 cord causes glycosuria can not, therefore, be 

 taken as a proof of the existence of efferent 

 fibers which control the glycogenic function of 

 the liver. Dyspnea may be the cause of the 

 hyperglycemia in these cases. 



Regarding the other evidence, which is sup- 

 posed to point to the existence of such fibers, 

 the authors stated that in all the experiments 

 on which it is based (viz., cutting the splanch- 

 nics, or sympathetic chain, or certain roots, 

 or the spinal cord) there must have been in- 

 duced by the operation, a great fall of blood 

 pressure which, in the cases of dogs with vagal 

 glycosuria, Macleod and Dolley have shown 

 usually to cause a marked depression in the 

 reducing power of the urine. 



Conclusion. — When every precaution is 

 taken to prevent asphyxia the authors have 

 been unable, so far, to demonstrate the exist- 

 ence of any efferent fibers whose stimulation 

 causes hyperglycemia. 



William J. Gies, 



Secretary 



THE BIOLOGICAL SOCIETY OF WASHINGTON 



The 424th meeting was held January 26, 

 1907, with President Stejneger in the chair. 



Mr. H. W. Clark described some observa- 

 tions on Biccia, luiescens and R. natans. 

 Among the many examples of adaptation in 

 plants to alternating conditions of drouth and 

 moisture, conditions which prevail most stri- 

 kingly in temporary ponds, perhaps the most 

 remarkable is that furnished by Riccia lute- 

 scens. 



One of the first things to catch the eye of a 

 visitor to the shallow woodland ponds of the 

 northern states is a fleet of little fronds float- 

 ing on the surface roughly resembling small 

 green butterflies in general appearance. The 

 plants would probably be found to be actively 



dividing into equal parts by a sort of decay 

 along a median groove, a form of reproduce 

 tion strikingly resembling that of single cells 

 and lower organisms. Each frond has its 

 under surface beset with long rhizoid-like 

 scales which act as balancing organisms, so 

 that if a frond is overturned it immediately 

 rights itself. According to descriptions in 

 books the plant just noticed is Riccia, {Riccio- 

 carpus) natans. 



A visit to the same pond during the dry 

 season would reveal numerous orbicular or 

 elongate thalli creeping on the moist ground. 

 These would be determined at once according 

 to the literature as R. lutescens. 



A third visit to the same pond some time 

 after the rains had filled it would result in the 

 discovery of the lately creeping fronds lifted 

 to the surface, and in all stages of change to 

 the floating phase. Experiments with the 

 plants at the proper season — slowly drying 

 basins containing floating phases, or slowly 

 raising the water surface on the creeping 

 phases — will result in the change of one phase 

 to the other. These experiments might not 

 be perfectly satisfactory, however, if attempted 

 much out of season, for the plant has long 

 been accustomed to making these changes at 

 certain seasons, and would probably yield to 

 treatment more readily at such times. About 

 ten years ago, while attempting the experi- 

 ments indicated with these plants during the 

 spring, they fruited abundantly. 



In view of these facts, one might naturally 

 assume that R. lutescens and R. natans are 

 different phases of the same species ; this con- 

 clusion has indeed been darkly hinted at, and 

 finally distinctly stated by one author.' 



A visit to the marshy edge of one of our 

 lakes or permanent ponds, however, will reveal 

 the real R. natans a smaller plant than B. 

 lutescens, with deep purple tinge about the 

 edge and in the balancing scales. The bal- 

 ancing scales themselves are much more fully 

 developed in R. natans and form a more con- 

 spicuous part of the plant as a whole. 



' Charles E. Lewis, Bat. Gazette, XLI., No. 2, 

 pp. 109-138', where a graphic account of all these 

 changes are described and illustrated in full, and 

 the genus is pretty thoroughly revised. 



