364 General Notes. [June, 
result, that they have opened a new horizon upon a simple and general 
eory. é, 
Professor Morren closes his paper by stating his hope and desire to 
go still further in this difficult and interesting line of research. — BY- 
RON D. Hatstep, Bussey Institution, March 14, 1877. 
On THE Porosity or Woop. — Professor Sachs has published a — 
preliminary communication in regard to the porosity of wood, which 
contains notes of many interesting experiments. Two of these will be 
_ how briefly noticed. 1. The best grade of artist’s vermilion was treated 
with a large quantity of distilled water and repeatedly filtered through 
filter-paper. The pigment was now left in so fine a state that it exhib- 
ited the well-known Brownian movement. Fresh cylinders of wood 
three to four em. long, cut from a living stem of a conifer, were fastened 
to the lower end of a glass tube which at the upper part communicated 
with a broad vessel ; tube and vessel were filled with the pigment emul- 
sion so that the wood was under a constant hydrostatic pressure of 160 
em. Even at the end of three days the water which filtered through was 
perfectly clear and contained no trace of the vermilion. The upper trans- 
verse sections of the cylinders showed that all the layers of the spring- 
wood were bright red, the autumn layers were not red at all, or at most 
only in radial stripes, the heart-wood was wholly uncolored. On split- 
ting the cylinder of wood, the vermilion was seen to have penetrated no- 
where deeper than two to three millimeters, corresponding to the length 
of the cells in the wood employed; the rest of the wood was colorless. 
The microscope shows that the majority of the spring-wood cells are 
wholly filled with vermilion even to their lower tips; also that the bor- 
dered pits of these cells are thickly filled with vermilion, and sometimes 
this did not pass through into the neighboring cells which seemed to be 
in communication with them; there was obviously an obstruction in the 
bordered pits themselves. This is interpreted as showing that there 
still remains in the discoid markings, a thin membrane as claimed by 
Hartig. The autumn wood cells appeared to take up very little vermil- 
ion, and the medullary rays none. “These results confirma Hartig’s and 
Sanio’s views, that the bordered pits of the spring and a part of the 
autumn wood are closed. Nevertheless there exist at the dividing line 
between the autumn and spring wood passages which allow air to pen- 
etrate.” ‘The latter is shown by fastening a three to four em. cylinder of 
wood from a living stem, to a bent tube holding mercury and by this 
means exerting a pressure of fifteen to twenty ct. If the whole is placed 
under water, the line between the autumnal and the spring wood will be 
seen to emit a circle of bubbles; but no air bubbles will escape from the 
first autumnal cells or the last spring cells. This experiment has been 
tried with the wood of the fir in January, and with Pinus Laricio, Pinus 
Brutia, and Pinus pinsapo in February. Both fresh and air-dry fir gave 
