1847-] Linnean Socitty. 347 



its origin in the hlastoderma, and being composed entirely of cells, 

 like the young tissue of plants. The form of the body of the em- 

 bryo entirely depends on the changes which take place in this struc- 

 ture, and the principles which regulate these changes regulate also 

 those of the whole life of the insect. 



The growth of the tegument of the young larva Mr. Newport 

 showed to depend on the division of the nuclei of its cells ; that 

 the subsequent consolidation of the tegument in the formation of 

 the hardened dermo -skeleton of the insect is the result of the secre- 

 tion of earthy materials by the nuclei of the tegumentary cells, in a 

 manner similar to that in which bone is formed in the Vertebrata, by 

 the calcification of the cells in layers of the surface of the peri- 

 osteum, as shown by Hunter, Flourens, Goodsir, Sharpey, Tomes 

 and others ; and that this is analogous to the mode in which the 

 woody fibre of exogenous trees is formed on the inner surface of 

 their bark. The earthy constituents of the dermo-skeleton were 

 stated, from the chemical analyses of Odier, Lassaigne and Mr. Chil- 

 dren, to consist chiefly of phosphate of lime, with carbonates of potass 

 and lime, and a little phosphate of iron, and in some species with 

 traces of silica, magnesia and manganese ; materials which, ten years 

 ago, led Mr. Newport to describe the dermo-skeleton of insects as 

 " an imperfectly-developed condition of bony matter," a view which 

 has recently been much supported by the discovery by Platner of 

 star-shaped corpuscles in the tegument of the silkworm, closely re- 

 sembling those of true bone in the Vertebrata. 



The tegument of insects is thus regarded as analogous in its mode 

 of development, as in its function, to that of the skeleton of the Che- 

 Ionian Reptiles. This structure in the very young Melo'e was then 

 fully described, and the nature of its appendages and functions exa- 

 mined. The spines and hairs were shown to originate from the centre 

 of tegumentary cells, and were regarded as excessive developments 

 of the nuclei as single bodies. The growth and development of the 

 tegument was shown to be efi^ected by means of the enlargement and 

 fissiparous division of the nuclei of the cells, and the subsequent ex- 

 pansion of these into cells, the nuclei of which undergo similar 

 changes. This was pointed out as being strongly confirmatory of 

 the theory of Schwann with reference to the tissues generally, and 

 as being in full accordance with the observations of Kolliker on the 

 yolk cells, and with original observations which Mr. Newport has 

 himself made on other structures. 



The formation of the external respiratory organs was then exa- 



