On the Generation of the Pol^ gastric Infusoria. :185 



Point Petre tlie atmosphere was so impregnated with the effluvia arising 

 from the ruins of the town, as to be quite unsupportable. The comet 

 recently seen at this phice was observed at St Thomas's on the 2d April, 

 and was so brilliant, as to cause considerable alarm to the inhabitants. 

 A shock of earthquake was also felt at St Thomas's on the 5th instant, 

 about half-past nine at night. No material damage was done. 



On the Generation of the Folygastric Infusoria. By Professor 

 Owen, F.R.S., &c.* 



Perhaps the most marvellous part of the organization and economy of 

 the Polygastric Infusoria is that which relates to the function of genera- 

 tion. This function, I may observe, is the only one which does not ne- 

 cessarily require a special organ for its performance. I am not aware 

 that this proposition has been before enunciated, but it will be quite in- 

 telligible when the essential nature of the generative process is better 

 understood. 



Although both ovaria and testes have been unequivocally demonstrated 

 in the Polygastria, yet their most common mode of propagation is quite 

 independent of, and superadded to, the function of these organs. In a 

 well fed Monas, Leucoj>hrys, Enchdi/s, or Paramecinm, the globular paren- 

 chyme may be observed to become a little more opaque and apparently 

 more minutely vsubdivided : then a clear line may be discerned, stretch- 

 ing itself transversely across the middle of the body and indicating a se- 

 paration of the contents into two distinct parts. The containing inte- 

 gument next begins to contract along this line, and the creature to as- 

 sume the form of an hour-glass. This, though doubtless an uncontrol- 

 lable, seems to be a spontaneous action, andthestruggle of each division 

 to separate itself from its fellow indicates an impulse in each to assume 

 its individual and independent character ; the which they no sooner ef- 

 fect than they dart off in opposite directions, and rapidly acquire the 

 normal size and figure. In the Vorikella and some other species, we 

 have examples of spontaneous division in the longitudinal direction, 

 which commences at the mouth, and extends to the irritable and con- 

 tractile stem, from which one or both of the new formed individuals de- 

 tach themselves. In some species, this spontaneous fission, which cor- 

 responds, as I stated in vny Lectures on Generation in reference to the 

 ova of the Medusa, in so interesting a manner with the earliest pheno- 

 menon in the development of the ovum in the higher animals, is arrested 

 before its completion, but the partiall}- separated individuals continue 

 in organic connection, and form compound animals, sometimes in the 



♦ From the Hunterian Lectures on Comparative Anatomy, delivered at the 

 Royal College of Surgeons, London, in 1843, p. 22, &c. 



