Earth's Rocks to Meteorites. 241 



or else are turned away so as not to cross the earth's orbit. 

 Comets, by their strange behavior and wondrous trains, 

 have given to timid and superstitious men more apprehen- 

 sions than- have any other heavenly bodies. They have 

 been the occasion of an immense amount of vague and wild 

 and worthless speculation by men who knew a very little 

 science. They have furnished a hundred as yet unan- 

 swered problems which have puzzled the wisest. A world 

 without water, with a strange and variable envelope which 

 takes the place of an atmosphere, a world that travels 

 repeatedly out into the cold and back to the sun and slowly 

 goes to pieces in the repeated process, has conditions so 

 strange to our experience and so impossible to reproduce 

 by experiment that our physics cannot as yet explain it. 

 Yet we may confidently look forward to the answer of 

 many of these problems in the future. Of those strange 

 bodies, the comets, we shall have far greater means of study 

 than of any other bodies in the heavens. The comets alone 

 give us specimens to handle and analyze. Comets may be 

 studied, like the planets, by the use of the telescope, the 

 polariscope and the spectroscope. The utmost refinements 

 of physical astronomy may be applied to both. But the 

 cometary worlds will also be compelled, through ■ these 

 meteorite fragments with their included gases and peculiar 

 minerals, to give up some additional secrets of their own 

 life and of the physics of space to the blowpipe, the 

 microscope, the test-tube audthe crucible. 



Additional Notes upon the Tendrils of 

 cucurbitace^]. 1 



By D. P. Penhallow. 



During the past summer, opportunity was presented for 

 the extension of previous observations upon tendril move- 

 ments in several important particulars, and the results 



1 The facts contained in this paper were nearly all obtained at 

 the Botanic Gardens of Harvard University. For the facilities 

 there placed at my disposal, and for many courtesies extended, the 

 author is under deep obligations to Dr. Gray and Dr. Goodale. 



