( xxxviii ) 



in the malpigbian tubules, and confirmed Mr. Bell's results. 

 With the help of Mr. A. Gr. Vernon Harcourt, its chemical 

 nature was investigated in the laboratory of Christchurch, 

 Oxford. The yellow colour was destroyed at a comparatively 

 low temperature, leaving the crystals unaltered : the former 

 is therefore in all probability some unstable organic pigment. 

 The stabiHty of the crystals at high temperatures proved them 

 to be inorganic, and they were then found to dissolve with 

 effervescence in dilute hydrochloric acid, while calcium 

 chloride was proved to exist in the solution. This, with the 

 fact of effervescence, showed that the crystals are carbonate 

 of lime. The presence of calcium was then confirmed by 

 spectroscopic tests. A specimen of the powder was sent to 

 Mr. H. A. Miers, of the Mineralogical Department of the 

 Natural History Museum, who concluded that the crystals 

 were in the form of Aragonite. 



Mr. Stainton said he should like to know if Mr. Poulton 

 was certain as to the source of this powder in larvae. 



Mr. Poulton stated that, as he had already explained, the 

 powder was contained in a crystalline form in the malpighian 

 tubules of the larva, and was discharged from the anus. 



Lord Walsingham commented on the interesting nature of 

 the experiments, and asked Mr. Poulton if he had ever 

 examined in a similar way the powder on the scales of the 

 wings of Lepidoptera. Mr. Poulton replied that he had not 

 yet done so. 



Mr. M. Jacoby enquired if the powder on the pupa of Catocala 

 nupta had ever been subject to a critical examination. Mr. 

 Poulton said he was not aware that it had. 



Mr. M'Lachlan asked Mr. Poulton if he was quite satisfied 

 that the malpighian tubes were renal organs. He said he 

 believed many entomologists considered that they were biliary 

 organs. 



Mr. Poulton replied that Dr. MacMunn (of Wolver- 

 hampton) had described a simple process by which crystals of 

 uric acid could easily be extracted from the tubules. The 

 liver of Vertebrates is an excessively complex organ, with 

 many functions, and it is very doubtful whether any single 

 organ among the Invertebrates corresponds to it with any 



