471 



2. The fibres in these columns do not convey impressions directly 

 and continuously to the brain as hitherto supposed, but enter the 

 grey matter, and operate through the ganglionic cells of that 

 matter. 



3. That all so-called reflex movements are carried on by a 

 definite system of conducting fibres and ganglionic cells, passing 

 through the grey matter ; in other words, they are diastaltic and 

 not reflex. 



4. That the particular fibres and cells which are necessary to 

 spinal diastaltic acts have yet to be discovered ; so that a new 

 field of inquiry is opened up to the physiological histologist. 



2. On the Delta of the Irrawaddy. By T. Login, C.E., Pegu. 

 Communicated by William Swan, Esq. 



Little is known of the course of the Irrawaddy River above Ava, 

 and as it is joined by no large tributary near its mouth, its sec- 

 tional area differs very little for hundreds of miles. At Prome, 

 a distance of 190 miles in a direct line from the sea, the river is 

 confined between two ranges of hills. The eastern range passes 

 through the Tharawaddy district, separates the Irrawaddy from the 

 Sittang Valley, and is lost in low undulating hills at Rangoon. The 

 western or Aracan range is more mountainous, and terminates in a 

 bluff headland forming the right bank of the Bassein River at its 

 mouth. The plain bounded by these two ranges is inundated when 

 the river is in flood — so much so, that it can be traversed in almost 

 any direction in small canoes. 



The Irrawaddy, like all other large rivers in India, begins to rise 

 in March, and attains its highest elevation in August, after which it 

 gradually subsides, until it is again swollen by the melting of the 

 snows among the hills, when it rises from 10 to 12 feet before the 

 setting in of the rains. 



My observations were made at Than-ba-ya-doing in March 1855, 

 with as great care as circumstances would permit, to determine the 

 discharge, velocity, slope, and the proportions of earthy matter 

 suspended in the water. It was found that, when the river was at 

 its lowest, it discharged 75,000 cubic feet per second. The mean 

 surface velocity was IJ miles in the hour, the slope If inches in 

 the mile, and the proportion of earthy matter was yyV? hy weight. 



