Ixxxiv THE BEGINNINGS OF LIFE. 



freely. But Itzigsohn says : ' If a number of these remain 

 conjoined, and move about with a rowing kind of movement, 

 their locomotion being governed by a common spontaneity, 

 they represent a Volvox-like colony, which, perhaps, may 

 even have been described as Volvox by authors. The micro- 

 gonidia of the Euglence, like those of all the Algae hitherto 

 examined by me, are the motile parent cells of extraordinarily 

 minute spiral filaments. They are at first green, gradually 

 becoming pellucid exactly like the " Spermatospheres " of 

 Spirogyra, presenting a monadiform aspect. A peculiar 

 appearance arises when many microgonidia, in such groups, 

 remain green whilst 'the others have already become clear as 

 water; the mass then presents, in fact, the aspect of being 

 composed of two kinds of animalcules. Such or similar con- 

 ditions would represent several species of the supposed genus 

 Uvella (atomus, glaucoma, Bodo, &c.). Each ultimately colour- 

 less microgonidium, then, by the dissolution of its minute 

 gelatinous envelope, discharges a small motile spiral filament. 

 . . . These spiral filaments do not seem to be destined for 

 the purposes of impregnation ; for they gradually increase in 

 length and thickness, soon exhibiting numerous spiral turns/ 

 They, in fact, exchange their Spirilla-like for a Spirulina-fonn.. 

 1 Finally, when their motile faculty has become weakened, 

 they affix themselves by one extremity to any larger object 

 near (e.g. Conferva filaments, &c.), whilst the other extremity 

 continues to move about with a creeping motion the pecu- 

 liar Oscillatorian movement, in performing which a young 

 filament frequently returns to the spiral. The last described 

 condition constitutes the Leptothrix of authors. The fila- 

 ments now gradually become thicker; and though at first 

 of the lightest emerald-green, they gradually assume a deeper 

 and deeper tint. The first indications of articulation are 

 perceptible in them, until at last a young Oscillatoria is again 

 perfected/ 



