28 HOFFMANN ON THE CIRCULATION 



result which stands in contradiction with the experiments already 

 related on Monocotyledons and Acotyledons at the time of the 

 full activity of the leaves (vide infra). 



Comparison of the Experiments 5 and 6 with 4, shows how- 

 much more quickly the fluid runs through the tissues when it is 

 placed in contact w r ith open wounds, than when the absorption 

 is allowed to take place in the normal way by the root. In 5 

 and 6 the ferrocyanide traversed some 8 feet, down from the 

 cut branch to the orifice, in one day; in 4 it occupied seven days 

 for the salt with which the soil (root) was watered to ascend to 

 an orifice 1 foot above the ground. In the former there were 

 open communicating tubes, in the latter closed membranes only 

 permeable through endosmose. 



7. In a young sycamore of about 3 inches diameter, a root on 

 the west side, A, an inch in diameter, was laid bare, cut through 

 at the distance of a foot from the trunk, and the upper end 

 placed in a cylindrical glass of 1 cubic inch capacity, containing 

 solution of ferrocyanide. An orifice B was made at a height of 



1 foot above the soil, on the south side of the trunk, and a glass 

 vessel fixed under the quill introduced into it. On the following- 

 day (March 5th) the vessel at A was found empty, and was 

 refilled ; B w r as half full of fluid (^ a cubic inch). On March 

 6th, A, again empty, was again refilled ; B contained ^rd of a 

 cubic inch of fluid. On the 7th, A as the day before ; nothing 

 emitted from B. On the 9th, A empty. On the 10th, A was 

 refilled ; B contained fluid again (J a cubic inch), evidently in 

 consequence of warm weather the day before. None of the 

 exuded fluid gave reaction with salt of iron. On the llth, 

 nothing emitted from B. A new hole C was bored on the west 

 side, corresponding to the root A, 6 inches above the ground, 

 but nothing flowed from it up to the 13th. Although, there- 

 fore, the fluid had been absorbed, it was impossible this time to 

 draw it from the stem here by tapping ; evidently because the 

 orifice B, which alone emitted fluid, was not made on the cor- 

 responding side of the stem. The observations were made at 



2 P.M. each day. 



On the 13th of March the absorbing root was cut off and 

 dissected. Reaction with sulphate of iron and hydrochloric acid 

 showed that the exceedingly small pith had not conducted. At 



