Dr Brewster wi the motions of the Molecules of Bodies. 217 



rally of a light straw colour^ while the central one is steel blue, 

 like the main spring of a watch, or of a red or light rose co- 

 lour, sometimes silvery, green, or purple ; but never of the 

 same colour as the extremities of the spiculum. The colours 

 of the different joints do not shade into each other, but termi- 

 nate abruptly by a well defined line."" 



Dr Drummond next proceeds to account for the motion of 

 these spiculae, and after discussing many objections against 

 the supposition that they are animalcules, and especially the 

 formidable objection drawn from their surviving the heat of 

 boiling water, he concludes with the following opinion of their 

 probable origin. 



" Perhaps many other objections may be opposed to the 

 supposition of animalcular life in these bodies, and yet the 

 strong expression of animation, if I may so term it, and air of 

 seeming design, with which the varying motions (sometimes 

 slow and sometimes rapid) are performed, and the difficulty 

 of otherwise accounting for their motion, whether real or ap- 

 parent, lead, upon the whole, T think, to this supposition, not 

 as one which we can admit with confidence, but as the least 

 improbable conjecture, which, in the present limited state of our 

 knowledge, we can venture to form."" 



Although I never could assent to this conclusion, yet I can 

 bear testimony to the perfect accuracy of the statement pub- 

 lished in Dr Drummond's paper. The late Dr Thomas 

 Brown and I repeated most of the experiments, and witnes- 

 sed all the movements and revolutions of the spicula above-men- 

 tioned. I was disposed at that time to regard them as the re- 

 sult partly of a polarity in the spicula themselves, and partly 

 of certain physical changes, to which bodies are peculiarly li- 

 able when suspended in a fluid medium. 



In order to determine whether or not these minute scales 

 acted upon one another, I prepared a considerable quantity of 

 the milky fluid, and spread it out upon a large square of glass, 

 in the expectation that the spicula would (like the minute par- 

 ticles of crystalline matter) form an organized film that would 

 exhibit the proof of molecular polarity by its action upon po- 

 larized light. When the water had evaporated, I obtained a 

 film or crust exactly similar to that which converts glass balls 



