May — June, 1832. terrestrial planari^. 31 



are longitudinally striped with several bands of gay colours. 

 At first sight there is a remarkable false analogy between 

 these animals and snails, although so widely separated 

 from each other in all essential points of organization. 

 I suppose these Planariae feed on rotten wood, for they 

 are always found crawling on the under surface of old 

 decayed trees ; and some small specimens being kept with 

 no other food, rapidly increased in size. Although gaily- 

 coloured little animals, they dislike, and are very sen- 

 sitive to the light. Some specimens which I obtained at 

 Van Diemen^s Land, I kept alive for nearly two months. 

 Having cut one of them transversely into two nearly 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 consequence, 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 towards its posterior 

 end, a clear space was formed in the parenchymatous mass, 

 in which a rudimentary cup-shaped organ could clearly be 

 distinguished; on the under surface, however, no corre- 

 sponding sht 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 structure. Although so well- 

 known an experiment, it was interesting to watch the gradual 

 production of every essential organ, out of the simple extre- 

 mity of another animal. It is extremely difficult to pre- 

 serve these Planariae ; immediately 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. A method of preservation that I found 

 answered pretty well, was to dry the whole animal rapidly 

 on a thin plate of mica, for the body thus becomes 

 transparent, and allows the internal structure to be seen. 

 I first visited the forest in which these Planariee were 



