THE BEGINNINGS OF LIFE. 163 



enchanting to those who examine with the microscope 

 the motley inhabitants of ponds and stagnant waters. 



Again, the transitions and metamorphoses which 

 have been observed and carefully recorded by innu- 

 merable workers as occurring amongst many of these 

 forms, are similar in kind though much easier to sub- 

 stantiate than those which have now been definitely 

 proved to exist between Bacteria.^ Torul£^ Fungiy Amoebie^ 

 Monads, and various kinds of Alg£. 



The admirably complete investigations of Dr. Brax- 

 ton Hicks 1, Itzigshon and others, had already taught 

 us how close is the alliance which exists between such 

 modes of growth as Frotococcus'^ and the various fila- 



^ See Appendix D, pp. liii et seq. 



2 After speaking of some experiments in which Protococcus or the 

 so-called ' green matter ' of Priestley made its appearance, Burdach adds 

 (loc. cit., t. i. p. 25) : — • Du marbre ayant etd egalement renferme dans 

 un flacon, avec de I'eau distillee et de I'air atmospherique, de I'oxygene 

 ou de I'hydrog^ne, puis expos^ a la lumiere du soleil k la chaleur du 

 bain-marie, il ne se produisit pas de matiere verte, mais vme substance 

 mucilagineuse avec de filaments blancs, dont quelques uns dtaient rami- 

 fies. Des morceaux de granite qui venait d'etre detaches du milieu d'un 

 bloc, et que j'enfermai avec de I'eau distillee et du gaz oxygfene ou hydro- 

 gbne, donnerent au soleil de la matiere verte, avec des filaments confer- 

 voides, et au bain-marie des flocons seulement.' Retzius also observed, 

 as Miiller says, that a ' peculiar kind of Conferva was generated in a 

 solution of muriate of baryta in distilled water, which had been kept 

 half a year in a bottle closed with a glass stopper.' Protococcus has also 

 been observed by many to form upon the sides of glass vessels containing 

 distilled water when they remain undisturbed for some time in warm 

 weather, and are exposed to sunlight. Prof. Schaffhausen, indeed, even 

 says (' Cosmos,' i860) that he has seen green Protococci develop within 

 hermetically-sealed vessels containing tolerably pure boiled water when 

 the flasks have been exposed to sunlight. These various facts seem 



M 2, 



