18 KANSAS Academy of Science. 



NOTES ox CIRCULATION OF SAP. 



BY W. E. LKiHTON. 



I wish to call your attention briefly to some of the results obtained in the per- 

 formance of several experiments upon the sunflower, bearing upon a question of 

 considerable interest — the circulation of sap. 



First, in the early spring, when the stalks of my more vigorous plants had at- 

 tained a diameter of about three-quarters of an inch, I had recourse to a venerable 

 experiment — the simple binding of a string tightly about the stem. 



In several of the plants selected the growth was so vigorous and the bark so 

 tender that as the stem increased in size the string cut through and was imbedded 

 in the tissue beneath; but in several other cases the experiment was a success. 



After the operation of tying, the stalk continued to develop normally above the 

 ligature, except for a space of about two inches immediately above it, where there 

 was an abnormal increase in the size, while careful measurements showed that fur- 

 ther growth below the string was almost entirely checked. 



This partial stoppage of the circulation apparently did not interfere in the least 

 with the process of maturing of the plants, as they went on uninterruptedly to the 

 completion of their mission, and reached the periods of flowering and seeding at the 

 same time as did their brothers with which I had not interfered, and there was no 

 noticeable decline in the vigor of the leaves and branches above the stricture — in 

 fact there were many of the plants which were growing within a few feet and not 

 subjected to the tying process which were much less healthy in appearance. 



When further growth of the stalks had stopped I made careful measurements, 

 which showed that the average height of the tied plants was equal to that of the 

 plants not tied, some of them reaching a height of fifteen feet. 



As before stated, the growth of the stalk below the ligature was almost, or quite 

 stopped, the circumference at this place in the larger stalks being but 2] to 3 inches, 

 while the circumference about a foot above the place of binding was from six to 

 eight inches in the same plants, and the circumference at the point of abnormal de- 

 velopment above mentioned was from eight to eleven inches. 



A number of dissections and microscopical examniations made after six weeks of 

 growth under these conditions showed that the stalk below the place of binding had 

 an extremely small quantity of cellular tissue in its composition, but was composed 

 almost altogether of the vascular or woody tissue, while the stalk above showed, as 

 compared with other stalks in normal condition, the usual development of cellular 

 tissue, while the enlargement just above the ligature showed an excessive develop- 

 ment of the cellular tissue. 



Other stalks were tied later in the season, before the time of flowering, but when 

 the stalks had attained to almost their full size, but these effects were not observed, 

 with the exception of one case where there was a slight enlargement. 



As you know, in the performance of a surgical operation it frequently becomes 

 necessary to tie an artery or large vein to prevent loss of blood, and in such case 

 the flow of blood thus stopped is diverted into other channels, and the smaller veins 

 or arteries having their duties thus increased, are increasd in size and strength in 

 proportion. 



Early in the season while the flow of sap was strong in the young plants, several 

 experiments were tried which gave results that would seem to approximate those ob- 

 tained in surgery under the conditions named above, although it is generally ac- 

 knowledged that there is no exact parallelism between the flow of sap in plants and 

 the arterial and venous circulation in animals. 



