( xxxix ) 



precision. The organ wliicli was formerly called the liver in 

 such an animal as the Crayfish is now more correctly called 

 the hepatic gland, because of the improbability of any true 

 analogy to the Vertebrate organ. The functions of the renal 

 organ are far more definite, and this term may be correctly 

 applied to any organ which eliminates nitrogenous waste. 

 Such elimination very commonly takes the form of uric acid, 

 and the normal presence of this substance as an excretion in 

 the tubules was sufficient warrant for describing them as 

 renal. The elimination of calcium carbonate in the case of 

 C. neustria was by no means antagonistic to the conclusion 

 that the organs are renal. If such a substance requires 

 excretion, it is far more likely to pass off by the renal organ 

 than any other. The occurrence of crystals of carbonate of 

 lime in the urine of herbivorous Vertebrates was well known. 

 The proportion of calcium in the leaves of plants is large, and 

 we must suppose that its excretion in the solid crystalline form 

 is delayed until the close of larval life, when the powder 

 would be of some value in assisting to render the cocoon 

 opaque. The last faeces ejected during larval life are often 

 peculiar in consistence, and in colour. Those of the larva of 

 Centra vinula are red. It is very probable that this, too, is 

 due to some substance which is excreted in large amount at 

 a corresponding period to that of C. neustria, only without the 

 excretion being of any ascertainable use to the species. 



Dr. Sharp said he believed that Mr. Griffiths had lately 

 written a paper on the malpighian tubes of Dragonflies, in 

 which he had shown that the function of these organs was 

 renal. 



Mr. Poulton also exhibited some photographs of the living 

 larvae oi Hemeropldla ahruptaria, showing the different depths 

 of colour which had been induced by experiment. Specimens 

 of the larvae preserved in spirit were also shown, together 

 with water-colour representations of the two varieties. As in 

 other experiments of the kind, the larvae had been rendered 

 very light by being surrounded by green leaves and stems 

 only, while they became extremely dark when an abundance 

 of dark twigs was intermingled with the leaves of the same 

 food-plant (lilac). All the larvae made use of were hatched, 



