102 THE MICROSCOPE. July, 



ocular giving me a magnification of 400 diameters. 



The petal was pink outside and white inside and the 

 microscope revealed the fact that the white cells were 

 inhabited by a transparent colorless liquid without any- 

 thing to mark it. But the pink cells had swimming 

 in the colorless liquid what I called then "oil globules " 

 which were colored some darker and some lighter 

 pink. These larger "oil globules" are in number one, 

 two or three and are perfectly quiet, or move 

 about with a slow motion like that of granules which 

 appear when ripe pollen is wet with water. That is to 

 say it is what is known as Brownian motion, and to under- 

 stand what is Brownian motion we can imagine a mass 

 of semi-solid white of egg is dropped into water. Now 

 it does not rest quiet but moves about sometimes this 

 way and sometimes that without any means or paddles. 

 And this it does for weeks or years at a time. 



This is Brownian motion and was so called because it 

 was first described by the celebrated Robert Brown in a 

 paper published in 1827. It is now known as pedesis, 

 and can be seen even in the contents of fluids in the old- 

 est rocks. The contents of the particles in these have 

 been going on most likely for seons. When I lectured 

 on chemistry in the New York Medical College for women 

 about thirty years ago I was in the habit of explaining 

 Brownian motion by likening it to a globule of Sodium 

 dropped on water which seems alive and moves about in 

 a lively manner. The motion here is chemical and it is 

 likely that all motion is accompanied by chemical action. 

 But, however that may be, the motion of the pink parti- 

 cles in the cells of Weigelia rosea is also Brownian. 

 Congregatingaround these larger "oil globules" there are 

 numerous smaller globules, pink in color and more vigor- 

 ously in motion. In time the large globules become 

 larger by gradual coalescence of the smaller and in time 



