THE BEGINNINGS OF LIFE. 493 



And, as a matter of fact, phenomena of this kind 

 have been long ago and quite independently recorded 

 by different investigators. Hitherto such observations 

 have been almost wholly discredited not because there 

 was any reason to suppose that due care had not been 

 exercised by those who made them, but simply because 

 the facts recorded were not in harmony with the theo- 

 retical views held by the majority of biologists. This 

 rejection of facts which do not accord with generally 

 received theories is unfortunately only too common. 



Two sets of observations which were made many 

 years ago, and quite independently of one another, are 

 to a certain extent complementary. The metamor- 

 phosis of Vorticella into Oxytricha was described by 

 M. Pineau in 1 848 ; whilst the metamorphosis of Oxy- 

 tricha into Trichoda was afterwards watched by M.Jules 

 Haime in 1855. 



M. Pineau's observations 1 were made upon speci- 

 mens of Vorticellas which had been developed in great 

 numbers in an infusion of Acomtum napellus. Some of 

 them were seen to undergo longitudinal fission and 

 produce buds in the usual manner, though others after 

 a time passed into the encysted condition. The body 

 contracted, assumed a spherical form, and produced a 

 secretion which soon solidified into a tolerably thick 

 cyst-wall, whilst the pedicle shrivelled and gradually 

 disappeared (Fig. 90, *, ) 2 . These encysted Vorticellx 



1 'Ann. des Sc. Nat.' 1848 (Zool.), p. 99. 



3 On other occasions a posterior ciliary wreath is developed, and the 

 organism separates from its pedicle before it begins to encyst itself. 



