BOTANY. 371 



directly seen by the eye; indeed, is considerably quicker than is needful for 

 being visible. And, to complete the parallel, as the leaves of the Sensitive- 

 plant, and the like, after closing by irritation, resume after a while their 

 ordinary expanded position, so the tendrils, in two species of the Cucarbit- 

 qcetv, or Squash family, experimented upon, after coiling in consequence of 

 a touch, will uncoil into a straight position in the course of an hour; then 

 they will coil up at a second touch, often more quickly than before; and 

 this may be repeated three or four times in the course of six or seven hours. 



My cursory observations have been principally made upon the Bur-Cucum- 

 ber (Sicyos angiilatns). To see the movement well, full-grown and out- 

 stretched tendrils, which have not reached any support, should be selected, 

 and a warm day; 77 Fahr. is high enough. 



A tendril Avhich was straight, except a slight hook at the tip, on being 

 gently touched once or twice with a piece of wood, on the upper side, coiled 

 at the end into 2? 3 turns within a minute and a half. The motion began 

 after an interval of several seconds, and fully half of the coiling was quick 

 enough to be very distinctly seen. After a little more than an hour had 

 elapsed, it was found to be straight again. The contact was repeated, timing 

 the result by the second-hand of a watch. The coiling began within four 

 seconds, and made one circle and a quarter in about four seconds. It had 

 straightened again in an hour and five minutes (perhaps sooner, but it was 

 then observed); and it coiled the third time on being touched rather firmly, 

 but not so quickly as before; viz., Ij turns in half a minute. I have indica- 

 tions of the same movement in the tendrils of the grape-vine; but a favor- 

 able day has not occurred for the experiment since my attention was acci- 

 dentally directed to the subject. I have reason to think that the movement 

 is caused by a contraction of the cells on the concave side of the coil; but I 



have not had an opportunity for making a decisive experiment. 







POMOLOGICAL USE OF SULPHATE OF IRON. 



M. Dubreuil has produced much larger fruits than usual by moistening the 

 surface of the green fruit with a solution of sulphate of iron, twenty-four 

 grains to a quart of water. This was done when the fruit first set, when it 

 was half, and when it was three-quarters grown, taking care never to do it 

 when the sun was shining. It has long been well known that this solution 

 greatly stimulated absorption. 



INSECT AND VERMIN EXTERMINATING POWDERS. 



The various termed insect and vermin exterminating powders (Persian, 

 Lyon's, etc.), now in general use, are composed essentially of the same mate- 

 rial, which has long been known to the Trans-Caucasian populations under 

 the name of " Guirila." In that paradise of vermin, it is an article of a 

 very considerable commerce, and is not only carried inland through Russia, 

 in large quantities, but is also exported to Germany and France. A large 

 de'pot exists at Vienna. It is a coarsely-ground powder, of a green color, 

 and penetrating odor, formed of the flowers of the pyrethrnm, carnenm, and 

 roseitm, which grow in the Trans-Caucasus at a height of five thousand or 

 six thousand feet. This powder possesses the peculiarity of rapidly stupe- 

 fying the insects, which soon afterwards die. Strewed about the room or 

 the bed, it proves a poison to fleas, lice, flies, etc. In the military hospitals, 



