72 Miscellaneous. 



week. The platform on which I deposited my potatoes is covered 

 with a layer of these little ^caW, which simulate an animated dust of 

 a grey colour. In a very short time one might collect considerable 

 quantities of them. This living powder consists of individuals of 

 different ages. We find in it adult specimens in copulation, gravid 

 females, and young individuals in all stages of development. 



This immense assemblage has attracted, as usual, many other 

 small carnivorous insects, which have found in it an abundant ban- 

 quet- There are larvae and perfect insects belonging to various 

 genera of Coleoptera, Diptera, Hemiptera, &c., to which the Acari 

 attach themselves in innumerable quantities — giving them a most 

 singular aspect. These insects, thus covered with mites and com- 

 pletely unrecognizable, run about amongst them, and probably de- 

 vour a great number of them. 



All the potatoes, which have still the most healthy appearance, 

 are nevertheless covered with these Acari. As they can no longer 

 all remain upon the surface of these, they accumulate in the inter- 

 stices of the paving- stones, then upon the paving-stones themselves, 

 on which they form a layer of several millimetres in thickness, over 

 a space of about four square metres. 



I intend to keep a certain quantity of these potatoes, to see whe- 

 ther they can be preserved sound for a longer or shorter time. It 

 would be, I think, very interesting to ascertain whether these innu- 

 merable Acari are the consequence of the disease of the tubers (as 

 in the pedicular disease of man) or the more or less proximate cause 

 of an alteration which will manifest itself at a later period. — Comptes 

 Rendus, October 1, 1866, pp. 5/0-571. 



Experiments demonstrating that the members of the Newt (Triton 

 cristatus) are only regenerated when their basal portion at least 

 is left in its place. By J. M. Philipeaux. 



In 1865 the author found that in the rabbit and the marmot the 

 spleen is regenerated only when a portion of the organ is left behind. 

 This observation led him to think that the regeneration of the limbs 

 of Newts, which has been long known to occur, may also require the 

 same condition. He therefore made some experiments on Triton 

 cristatus, in which he extirpated not only the anterior limb itself, 

 but also the scapula. In all these cases there was no appearance of 

 regeneration. He has specimens operated upon eight months ago, 

 in which the wound is completely healed, but not even the com- 

 mencement of a regeneration of the limb is apparent. 



In others, on the contrary, in which the anterior limb was cut off 

 at the surface of the body, as was done by Spallanzani, it was repro- 

 duced, with all its bones complete, within four months. The num- 

 ber of bony pieces in the anterior limb of the Triton is stated by the au- 

 thor to be forty-six ; the posterior limb consists of fifty-six such parts. 

 The author believes that he will be able to demonstrate similar facts 

 with regard to the reproduction of the fins of fishes, and thinks that 

 it will be found a necessary condition of the regeneration of organs 

 among the Vertebrata that some portion, at least, of the organ 

 should be left. — Comptes Rendus, Oct. I, 1866, pp. 5/6-5/8. 



