P OP ULAR MIS CELL ANY. 



429 



terminal, and can be transmitted to the brain 

 through the same nerve-fiber. From Lipp- 

 mann's recent researches on The Photogra- 

 phy of Color it appears that all parts of the 

 spectrum can now be photographed on films 

 of albumino-bromide of silver to which two 

 aniline substances, azaline and cyanine, have 

 been added. It seems, therefore, reasonable 

 to suppose that a relatively small number of 

 substances could enable all rays of the visi- 

 ble spectrum to affect the retina. It seems 

 to me that the question becomes narrowed 

 down to this, Do the nerve-impulses arise 

 from mere vibration or from chemical change 

 in the molecules of the nerve terminal ? The 

 photo-chemical hypothesis has much in its fa- 

 vor. We know how rapidly light can induce 

 chemical change in photographic films, and 

 we know that light induces chemical change 

 in the vision purple in the outer segments of 

 the rod-cells of the retina. The fatigue of 

 the retina produced by bright light is best 

 explained on a chemical theory, but it could 

 also be explained on a mechanical theory ; 

 for we must remember that even if the nerve- 

 impulses produced in the visual cells were 

 merely a translation of the energy of light 

 into vibration of nerve-molecules, the nerve- 

 impulse has to pass through layers of gangli- 

 onic cells before reaching the fibers of the 

 optic nerve, and in these cells it probably al- 

 ways induces chemical change. I have en- 

 deavored to place before you a subject that 

 involves physical and physiological considera- 

 tions of extreme difficulty. I have not at- 

 tempted to solve the difficulties, but rather 

 to show their nature." 



Work of the Forestry Division. — The 



year 1891, according to chief Fernow's re- 

 port, witnessed greater activity and interest 

 in forestry than any previous year. A bul- 

 letin, What is Forestry ? issued by the di- 

 vision, showed that the forestry interests of 

 this country rank second, if not first, in the 

 value of our annual products reaching the 

 market. The largest share of the expendi- 

 ture of funds as well as of attention was be- 

 stowed upon investigations into the charac- 

 ter of our timber trees, or " timber tests." 

 These relate to a judgment of mechanical 

 properties from a simple microscopic or ma- 

 croscopic examination, and to the determina- 

 tion of the relation in which structure, physi- 



cal conditions, and mechanical properties 

 stand to the conditions under which the tree 

 is grown. A wide and deep interest is mani- 

 fested in this work throughout the country. 

 In connection with it a study has been made 

 of the lumber pines of the Southern States, 

 the results of which are given in the present 

 report of the chief of the division. The re- 

 vision of the botanical and the common 

 names of our arborescent flora is nearly com- 

 pleted and will soon be ready for publica- 

 tion. Distributions have been made of pack- 

 ages of seeds of nine important conifers to 

 State agricultural experiment stations, and 

 twenty species of important conifers and de- 

 ciduous trees to general applicants, besides 

 seeds of the Australian tan-bark wattle to 

 applicants in the Gulf States, the arid South- 

 west, and the southern part of the Pacific 

 coast region. 



The Forcmnners of Matches. — Besides 

 the primitive devices for fire-making, Mr. 

 Walter Hough, in a paper on that subject, 

 describes several that were used in civilized 

 countries before matches became universal. 

 The brimstone match is found in Japan as a 

 broad, thin shaving tipped with sulphur ; in 

 Mexico it is a cotton wick dipped in sulphur. 

 These are used to catch the sparks from 

 flints or steels. The " spunk," or splint tipped 

 with sulphur, was in common use in this 

 country prior to 1825, and lingered in out-of- 

 the-way places long after the introduction of 

 matches. In parts of France it is still in use 

 with the briquet or tinder box. A variation 

 of the spunk match was curled shavings 

 tipped with sulphur. Attempts to supersede 

 the clumsy briquets produced the tinder piston, 

 the tinder wheel, and later the first chemical 

 match. The first employment of phosphorus 

 was by dipping the match into a bottle full of 

 phosphorous mastic mixed with oxide of phos- 

 phorus. The next was the "instantaneous 

 light box," " eupyrion," " dip splint," or, in 

 the United States, "match-light box" — a tin 

 box or wooden receptacle, containing a glass 

 bottle filled with asbestus soaked with sul- 

 phuric acid, and wood splints tipped with 

 sulphur and then dipped in a paste made 

 of chlorate of potash, powdered sugar, and 

 gum arabic, with water. The " prometheans " 

 were tubes of glass filled with sulphuric acid, 

 surrounded with an inflammable mixture 



