18 INTRODUCTION. 



extract of opium are very remarlcable : the motion is retarded 

 gradually, so that the play of these organs can be Avell dis- 

 tinguished. The iodine water, although it contains but an 

 extremely small quantity of iodine (70V0)' ^^'^ests suddenly 

 the cilia, wliich become plainly visible. The alcoholic 

 tincture of iodine may also be employed, but very Aveak. If 

 afterwards the spore is dried between two plates of glass, the 

 cilia will be sufficiently distinct to be seen by the simple 

 microscope. 



INI. linger has followed the movements of a liberated spore 

 in water during more than two hours. The greatest length 

 of time during which I have observed it with the microscope 

 has been nineteen minutes, and, in general, the motion con- 

 tinues but little more than half of this time : sometimes it ceases 

 almost immediately after the release. But it is necessary to 

 remark, that the spore, being placed upon the object glass, 

 was imprisoned between two plates of glass. The vibration 

 of the cilia continues sometimes after the spore is arrested ; 

 only it is not sufficiently strong to dls^^lace the corpuscle. 

 When at last they cease to move, the contour of the spore 

 undergoes during some instants a sensible alteration, whicli 

 announces, perhaps, the decomposition or the absorption of 

 the vibratile organs. The motionless spore delays not to 

 modify itself once again : it becomes spherical, the green 

 matter distributes Itself equally, and the episporic membrane, 

 in part reabsorbed, at last escapes the sight ; very soon ger- 

 mination commences. 



M. Unger remarks that the escape of almost all the spores 

 takes place towards eight in the morning. Indeed, all the 

 work of the formation of the spore is carried on in the first 

 hours of the day. The tufts which I have gathered the day 

 before, and which presented no indication of the formation 

 being near at hand, were in general covered with spores 

 the next morning ; and after mid-day these were all gathered 

 on the surface of the water beginning to germinate. 



It is easy to follow the progress of this germination under 

 the microscope : the elongation of the filaments progresses, 

 one might say, by eyesiglit ; for I have measured more than 



