Infusorial Ciretiit of Generations. 283 



or bulbous vessels radiating around the pulsatory vesicle, contract 

 as the vesicle expands, and vice versa, as is well known ; and some 

 seem to have several such ^uhatorij "vacuoles." The body is 

 turgid with rather small germinal yolks. These animals I have 

 never seen bisecting either lengthwise* or across, nor copulating 

 sexually. The latter, however, seems to take place with the Pla- 

 narise, which also show the staghorn-shaped entrails analogous to 

 those of the marine (true) Planariae and joints of the tape-worm, 

 whose detached individuals are also known to hover freely in a 

 liquid, hke these Ciliata. It is supposable that the large Para- 

 mecium, with pulsatory organs, is the young Planaria ; but it is 

 certainly not itself an adult body.f 



The further and most remarkable of all these progressive and 

 retrograde developments is the following. The well-fed and full- 

 grown but entrailless Paramecium Aureha becomes slow and lazy, 

 greyish with the teeming germinal contents, and in a few hours 

 may be seen motionless as the fabulous " Kraken " of ancient 

 Norway. Its entire substance now commences swelhng forth into 

 compact, fragiform " germinal clouds," while a great many of the 

 germinal specks, now become less obscured, are plainly discernible 

 as of the clear ^^ currant-shajyed yolks" kind. These in a short 

 time, however, commence moving, and while some of the smaller 

 ones are being propelled by adherent motile granules (probably the 

 " Acineta " Atict.), the larger ones move by contraction, viz. their 

 " circlet " becoming everted, they now crawl forth, like a very 

 limpid grub — resembling a sort of tunibling sac ! This " tumbling " 

 is produced by the most marvellous facility it possesses of protruding 

 long, blunt branches (like little stove-pipes) on any part of its 

 surface by eversion, so that in a few moments its form is entirely 

 changed. Its contents are a visibly and rapidly circulating so-called 

 " rotating protoplasm," composed of mostly very transparent indi- 

 vidual vihrionic jparticles, partly bulky, but mostly very small. 

 Some dark (red or brownish) vibrionic dots are also discernible. 



It now takes the form which has been called " Amoeba." This 

 form, however, likewise occurs when similar yolks or " acinetse " 

 are expelled from vorticellan bodies. In either case the " tumbhng 

 sac " lastly attains a versatile-campanulate star-shape with "pseudo- 

 podia," from which break forth volumes of minimal vibrios, and 

 quite large, cylindric bits of rods, or (pseudo)-" hactevia." The 

 latter here are thicker than fungine bacteria, and are neither coated 

 nor ellipsoidally shuttle-shaped, but bluntly cylindric, like car- 

 tridges or butting rams. They possess a very forcible automatons 

 motion, and like to congregate, and with great violence keep butting 

 all together, one against the other, in a heap ; and within a few 



* Ehrenberg's figures, however, show it in that process (if not a mistake). 

 t Pritchard, &c., figure tlie planaria-like form as " adult Paramecium." 



