22 HOFFMANN ON THE CIRCULATION 



of the same section, with the inner ends cut off obliquely and 

 the orifice looking upwards. These borings were made, 



B, 3 feet above the ground, on the west side. 



C, 3 feet above the ground, on the south side. 



D, 5 feet high, on the south side. 



On the 7th of March a clear fluid was first found in a vessel 

 attached below the quill (B), perhaps caused by rain which had 

 fallen on the 6th, and had run down from the stem. On the 

 8th of March the water (exuded from the stem) trickled from 

 B and C ; D remained dry. The fluid gave neutral reaction 

 with litmus paper. D did not become moist until the llth, 

 while B and C poured out abundance. The two last were closed 

 and cemented with resin on the 12th ; D was bored out 1 inch 

 deep, and a new hole was made of the same depth, 



E, 2^ feet from the ground, on the south side. 



The sap flowed immediately from both ; E delivered 70 drops 

 in five minutes, D only 15. On the 13th new traces flowed 

 from D; E gave 19 drops in five minutes. Both holes were 

 stopped and two new ones bored, 



F, 6 feet high, north side. 



G, 1 foot high, same side. 



F gave only traces, while G gave 32 drops in five minutes. 

 On the 14th F gave nothing, G 10 drops in five minutes. On 

 the 15th F was dry ; G gave 45 drops in five minutes. On the 

 14th a new hole was bored, 



I, 8 feet high, on the north side, which gave off no fluid on 

 the 14th or 15th. All these experiments were made at noon. 

 From the foregoing, the exudation and decurrence of the sap 

 occurred observably earlier in the lower than in the upper part 

 of the stem ; it was caused by a warmer temperature. 



All these fluids were tested for the ferrocyanide with sulphate 

 or acetate of peroxide of iron, without results. It is evident 

 that none of the holes entered the current of sap passing up 

 from the root A (vide infra). On the 10th of March the 

 ascending root A was cut off and examined. The section 

 5 inches above the point where it dipped in the fluid, reacted 

 strongly with salt of iron and excess of hydrochloric acid, and the 

 same occurred with the other parts ; the ferrocyanide had even 

 descended into the lateral branches of the root. The longitu^ 



