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On an Unusual Form of Tube made by Melicerta ringens. 



By T. Spencer Smithson. 

 {Read October 25th 1885.) 



While trying the well-known experiment of supplying Melicerta 

 ringens with powdered carmine in order to show the formation of 

 the pellets with which it constructs its tube, I had the good fortune 

 to be able to watch the building of the whole of one tube by a 

 young melicerta, which showed considerable deviation from the 

 ordinary type of architecture ; and I venture to bring the case 

 before the Quekett Microscopical Club as it appears to me to 

 possess several points of interest. 



In the first place the young melicerta began by building half a 

 course in the usual way with apparently solid pellets, but instead 

 of continuing to do so, it suddenly commenced to heap up, in a most 

 erratic manner, pellets of the ordinary shape, but composed of trans- 

 parent, gelatinous matter with a few particles of carmine imbedded 

 in it, giving the tube a somewhat mottled appearance. 



The walls of the tube, owing to the loose way in which they were 

 made, were about double the thickness of those constructed in the 

 usual manner. 



Since my first discovery I have found another young melicerta, 

 in the same trough as the first, beginning to build in the same 

 extraordinary manner, and this fact leads me to think that want of 

 material is the primary cause of this curious mode of building. I 

 merely offer this as a crude suggestion, and shall be very glad if any 

 member of the Club can give me a better explanation of this, as it 

 appears to me, interesting case of alteration of instinct by confine- 

 ment. 



I regret that I have been unable to send one of the tubes for 

 examination, but this would be impossible without great risk of 

 injuring the animals, both being attached to the side of a small 

 zoophyte-trough. 



