102 CIENKOWSKl's REMARKS ON DR. STEIN'S 



After waiting for a few weeks in vain^ I at last noticed 

 individuals containing rotating embryos. But tlie motion 

 was very slow, and the embryo often readied the surface of 

 the Acineta without its being able to make way through it, 

 in which case it perished. The number of rotating embryos 

 gradually increased, and their liberation, although very slow 

 (half to three quarters of an hoiir), may be frequently wit- 

 nessed. The half-freed embryo in these cases also moved 

 off with extraordinary rapidity. I determined to follow the 

 embryo in its hasty wanderings, and actually to convince 

 myself of the supposed transformation into a Vorticella. 



I endeavoured in the first place to retain as many full- 

 grown specimens oi Acineta, as possible, upon the object-glass, 

 so as not to be interrupted by any deficiency in the number of 

 " motile " embryos. I employed in the inquiry a simple 

 microscope of low power. Having fixed a large Acineta 

 containing a rotating embryo, I witnessed the liberation of 

 the latter, and followed it — by moving the object-glass — step 

 by step. 



The embryo traversed the drop of water from one side to 

 the other, in divers straight and undulating lines, as quick 

 as lightning. Upon meeting a mass of mucus or the edge 

 of the drop, it bounced back again — repeating the manoeuvre 

 on each occasion of the same kind ; sometimes, though more 

 rarely, the movement was circular around the margin of 

 the drop. 



Judging from what I had noticed in the division of the 

 Podophrya, I expected that the movement would not be of 

 long duration. But after a continuous observation for fully 

 five hoiirs of the active motions of the tiny brilliant point, a 

 determination of blood to the head obliged me to desist. 



A fresh drop of the infusion, in which two embryos were 

 in active motion, was observed at intervals of a quarter of an 

 hour. At the end of five hours the rapidity of the move- 

 ment Avas notably diminished — it became tremulous, and 

 then perhaps for a time as rapid and energetic as before. I 

 now placed the object under the compound microscope, and 

 continued my observation of the indefatigable embryo for 

 another quarter of an hour ; the embryo became stationary — 

 I awaited with drawn breath what would come next : its 

 form from oval became spherical ; at the border appeared 

 short, thick, equidistant rays, which after awhile were 

 developed into elongated, capitate tentacles (figs. 11, 12) ; 

 the contractile space was visible — and I coidd not longer 

 doubt as to the Acineta nature of the creature. This obser- 

 vation was twice repeated. 



