STATE HORTICULTURAL SOCIETY. 41 
professor's experience no such cold has been known. When a 
sudden change occurs from cold to heat whole orchards have been 
destroyed, the trees losing their bark on the side on which the sun 
strikes the tree. Mr. Latham inquired what the chemical pro- 
cess was that takes place when the tree is killed. 
Prof. Porter explained that the transfusion of sap from one cell 
to another ceases when the walls are ruptured. The flow of the 
sap has generally ceased, the growth has matured, and but little 
sap remains in the cells, the exhaustion of which is not sufficient 
to kill the tree. Why vitality is destroyed by a low temperature 
is an unsolved question. 
Mr. Harris stated that after warm weather started the sap, 10 
degrees below zero killed the trees dead, confirming Prof. Porter's 
theory of the crude sap rising under the influence of warm weath- 
er and freezing in the cell. 
Mr. Underwood thinks that the cold forces the sap out of the 
tree and leaves them nothing to subsist on. There are many reasons 
for trees dying. Bark-bursting is always accompanied by sudden 
changes. The unripened and unprepared condition of the tree 
has something to do with it. 
Mr. Howe thinks that the bark bursting is caused by extremes 
of heat on different sides of the tree, meaning in fact, the same 
thing as the previous speaker. 
Mr. Gibbs thought there was a close resemblance between ani- 
mal and vegetable physiology. 
Which was Prof. Porter’s opinion. 
My. Harris thinks the result is that we must get hardy varieties. 
We are working in the right direction. We have some and hope 
soon to have others to nail to: 
Mr. H. presents a resolution asking for the preparation of a 
directory of professional nurserymen, florists and seedsmen, and 
their agents, of Minnesota, domg a legitimate business and pub- 
lish them in the transaction of the meeting, which was lost. 
Prof. Porter requested the society to hold their Thursday morn- 
ing session at the university chapel, at 10 o’clock, which invita- 
tion was accepted. 
Discussion then ensued on Mr. Harris’ resolution, which after 
much emendation was lost. 
The chair then appointed committees on articles on exhibition, 
on final resolutions, and auditing committee. 
On Articles on Exhibition—Messrs. Fuller, Pearce and Howe. 
On final Resolutions—Messrs. Harris, Latham and Underwood. 
