34 RIO DE JANEIRO. 



I found no less than twelve different species of 

 terrestrial Planarias in different parts of the south- 

 ern hemisphere.* Some specimens which I ob- 

 tained at Van Diemen's Land, I kept alive for 

 nearly two months, feeding them on rotten wood. 

 Having cut one of them transversely into two near- 

 ly equal parts, in the course of a fortnight both had 

 the shape of perfect animals. I had, however, so 

 divided the body, that one of the halves contained 

 both the inferior orifices, and the other, in conse- 

 quence, none. In the course of twenty-five days 

 from the operation, the more perfect half could not 

 have been distinguished from any other specimen. 

 The other had increased much in size ; and to- 

 wards its posterior end, a clear space was formed 

 in the parenchymatous mass, in which a rudiment- 

 ary cup-shaped mouth could clearly be distinguish- 

 ed ; on the under surface, however, no correspond- 

 ing slit was yet open. If the increased heat of the 

 weather, as we approached the equator, had not 

 destroyed all the individuals, there can be no doubt 

 that this last step would have completed its struc- 

 ture. Although so well knowai an experiment, it 

 was interesting to watch the gi-adual production of 

 every essential organ, out of the simple extremity 

 of another animal. It is extremely difficult to pre- 

 serve these Planarice ; as soon as the cessation of 

 life allows the ordinary laws of change to act, their 

 entire bodies become soft and fluid, with a rapidity 

 which I have never seen equalled. 



I first visited the forest in which these Planariae 

 were found in company with an old Portuguese 

 priest who took me out to hunt with him. The 

 sport consisted in turning into the cover a few dogs, 

 and then patiently waiting to fire at any animal 



* I have described and named these species in the " Annals of 

 Nat. Hist.," vol. xiv., p. 241. 



