344 Mr. A. Henfrey on the Progress of Physiological Botany : 



of this latter display, often at a very early period, new minute 

 cellules filled with a granular substance, occurring in an inde- 

 finite number and sometimes appearing very regularly arranged. 

 They become more and more distinct, and in the mature condi- 

 tion generally fill up the parent-cell, so that this appears like a 

 sac distended with round granules. By reciprocal pressure they 

 acquire a parenchymatous aspect. When an organ of this kind 

 has reached the proper stage of maturity, it bursts spontaneously 

 at the apex and discharges an indefinite number of minute round 

 cellules enveloped in mucus. In some cases I have observed an 

 uniformly distributed, rhythmical motion of the whole discharged 

 mass. But the cellules usually exhibit a motion round their 

 axis very soon after their emergence ; each of them unfolds a spi- 

 ral filament, which generally remains connected with the deli- 

 cate cellule by its posterior extremity, and advances with an ac- 

 tive revolution round its axis. 



'' As Nageli has well described the very various movements of 

 these spiral filaments, it appears to me unnecessary to discuss 

 this subject here. But I must observe that I have seen on the 

 clavately swollen, anterior extremity of the spiral filament, de- 

 licate motile cilia of considerable length, which however are only 

 to be perceived distinctly with the help of the strongest artificial 

 illumination. They are best observed when the rapid revolution 

 of the filament is slackened. Then about six such cilia may be 

 observed on each, which after the cessation of the motion of the 

 spiral filament also gradually cease to move, and either stiffly 

 surround this or become in part so applied upon it that it is 

 almost impossible to detect them. The motion of the cilia en- 

 dures longer than that of the filament, and not unfrequently 

 shortly recommences. The form of the spiral filament cannot be 

 perceived distinctly either during active motion or after this has 

 ceased, because in the first case the form is altered by the con- 

 tinual change of the convolutions and the motion of the cilia, — 

 in the latter by the cessation of the revolution, as the filament 

 then contracts in irregular curves. It is necessary therefore to 

 seek out a moment when the spiral filament, sufiiciently mature, 

 still remains in its cellule, and occui's on a free space in the pre- 

 paration. In such cases it exhibits either two or three convolu- 

 tions, or appears wound in a semicii'cle with the swollen extre- 

 mity applied to the wall. The cilia are not then perceptible. 

 This position often gives a very well-defined figure. It is di- 

 stinctly seen that the spiral filament incloses a longish vesicle in 

 the above-mentioned clavate thickening of the anterior extre- 

 mity. The thick end diminishes gradually down into a fihform 

 tail which bears a slightly swollen knob at the end. 



