THE PRESIDENT'S ADDRESS. 377 



initiated by this young savant. It is, however, chiefly through the 

 writings of Cuvier and Latreille that we are acquainted with the 

 work of Savigny. Perhaps he felt, to quote the words of a celebrated 

 Italian, that research is " II Paradiso, composition, II Purgatore, 

 and publication, II Inferno." I know myself that I often feel the 

 truth of those words, but after nearly thirty years of II Paradiso I 

 have at last made up my mind once more to risk the result, and 

 give my researches to the world and I trust before very long, in 

 the shape of an amended and very much amplified " Anatomy of 

 the Blow-fly." 



Perhaps by far the best monograph on the anatomy of any insect 

 which has yet been written was published in Paris in 1828, 

 Straus Durckheim's magnificent volume, u The Anatomy of the 

 Cockchafer." 



No one who has not studied the anatomy of an insect down to 

 its most minute details can rightly appreciate the accurate detail 

 of Straus Durckheim's work. It is chiefly valuable in relation to 

 the hard parts of the integument, which we now term sclerites, but 

 which have been compared by all the earlier writers to the bony 

 skeleton of a vertebrate. 



There is one point which has struck me as of special interest in 

 relation to these sclerites, which are secondary indurations of the 

 cutaneous membrane. It is their strange persistency in the most 

 dissimilar types. This would not appear to me so extraordinary if 

 they appeared at an early period in the development of the indivi- 

 dual. But they do not, they appear at quite a late stage; yet in 

 the complex thorax of the fly I have been able to identify every 

 sclerite with the sclerites described by Straus Durckheim in the 

 thorax of the cockchafer. Just as the bones of the skull can be 

 compared in the most dissimilar types of the vertebrate, so the 

 sclerites of the thorax, if sufficiently carefully studied, can be com- 

 pared in the most dissimilar types of insects ; at least in those which 

 undergo a complete metamorphosis. If I dare to generalize at all 

 with regard to the relations of different insects from a phylogenic 

 point of view, it would be to assume that there is evidence that 

 similar sclerites have been formed independently by parallel lines 

 of descent from a common ancestral form in which they were 

 undifferentiated — at least admitting the theory of descent from 

 common and simple ancestors, that is the conclusion to which my 

 researches irresistibly tend. 



