THE AMERICAN MONTHLY 



[J anuary, 



old cellulose wall, leaving a very evi- 

 dent clear space. In a less notice- 

 able degree, this is also the case in 

 the other parts of the circumference 

 of the cell, and, apparently, the gran- 

 ular contents have secreted a separate 

 envelope, entirely distinct from the 

 parent filament. The grand climax 

 is now rapidly approaching. The 

 contents of the cell near its base are 

 now so densely clustered as to appear 

 nearly black (Fig. 3), while the 

 upper half is of a much lighter hue 

 and the separate granules are there 

 easily distinguished, and, if very close- 

 ly watched, show an almost imper- 

 ceptible motion. The old cellulose 

 wall shows signs of great tension, its 

 conical extremity rounding out under 

 the slowly-increasing pressure from 

 within. Suddenly it gives way at the 

 apex. At the same instant, the in- 

 closed gonidium (for it is now seen 

 to be fully formed) acquires a rotary 

 motion, at first slow, but gradually 

 increasing until it has gained consid- 

 erable velocity. Its upper portion is 

 slowly twisted through the opening 

 in the apex of the parent wall, tfie 

 granular contents of the lower end 

 flowing into the extruded portion in 

 a manner reminding one of the flow 

 of protoplasm in a living Amoeba. 

 The old cell wall seems to offer consid- 

 erable resistance to the escape of the 

 gonidium, for the latter, which dis- 

 plays remarkable elasticity, is pinched 

 nearly in two while forcing its way 

 through, assuming an hour-glass shape 

 when about half out. The rapid ro- 

 tation of the spore continues during 

 the process of emerging, and after 

 about a minute it has fully freed itself. 

 (Fig. 3). It immediately assumes 

 an ovoid form and darts oft' with great 

 speed, revolving on its major axis as 

 it does so. Its contents are nearly all 

 massed in the posterior half, the com- 

 paratively clear portion invariably 

 pointing in advance. When it meets 

 an obstacle it partly flattens itself 

 against it, then turns aside and spins 

 off in a new direction. This erratic 

 motion is continued for usually seven 



or eight minutes. The longest dura- 

 tion I have ever yet observed was a 

 little over nine and one-half minutes. 

 Hassell records a case where it con- 

 tinued for nineteen minutes. The 

 time, however, varies greatly, as in 

 some cases the motion ceases almost 

 as soon as the spore is liberated, while 

 in open water, unretarded by the cover 

 glass or other obstacles, its movements 

 have been seen to continue for over 

 two hours. 



The motile force is imparted to the 

 gonidium by dense rows of waving 

 cilia, with which it is completely sur- 

 rounded. Owing to their rapid vi- 

 bration it is almost impossible to dis- 

 tinguish them while the spore is in 

 active motion, but their effect is very 

 plainly seen on adding colored pig- 

 ment particles to the water. By sub- 

 jecting the cilia to the action of iodine, 

 their motion is arrested, they are stain- 

 ed brown and become very plainly 

 visible. 



After the gonidium comes gradu- 

 ally to a rest its cilia soon disappear, 

 it becomes perfectly globular in shape, 

 the inclosed granules distribute them- 

 selves evenly throughout its interior, 

 and after a few hours it germinates by 

 thi'owing out, one, two, or sometimes 



Fig. 4. — Clonidia germinating. 



three tubular prolongations which be- 

 come precisely like the parent fila- 

 ment (Fig. 4). 



Eminent English authorities have 



