726 THI-: GENERATIVE ORGANS. 



anatomy of the female generative armature. At the time he 

 wrote the importance of embryological investigations in elu- 

 cidating homologies was less understood than it is at present, 

 and he did not even attempt any study of the manner in which 

 these parts are developed. Lacaze-Duthiers' most important 

 generalisations were : 



(1) The external orifice of the sexual duct is very generally 

 situated between the eighth and ninth abdominal segments. 



(2) The stings and ovipositors of all Insects conform in their 

 general plan of structure, and exhibit homologous parts. 



(3) These parts are mainly formed by a modification of the 

 sclerites forming the ninth abdominal somite, and are not 

 homologous with ventral appendages, abdominal feet. 



\Yith regard to Lacaze-Duthiers' first generalisation, it is 

 apparently correct, but owing to the confused nomenclature of 

 the abdominal segments and the extensive modifications which 

 the posterior segments undergo, the statements of other inves- 

 tigators appear to show that there is no constancy in the 

 position of the external generative orifice. 



His second generalisation is indubitably correct, although 

 in matters of detail there are considerable discrepancies in the 

 views which have been propounded by different writers on the 

 subject. 



The third generalisation is, I think, undoubtedly erroneous. 

 Huxley, in 1877, wrote :* 'Thus it would appear that, while 

 there can be no doubt as to the general unity of plan of ovi- 

 positors and stings, the view of Lacaze-Duthiers must be 

 modified. It must be admitted that these apparatuses apper- 

 tain to the eighth and ninth somites, and not to the ninth 

 alone ; and that there is reason to suspect that their chief 

 constituent parts are modified limbs.' Such modified limbs 

 are usually termed gonapophyses. 



Comparison of the Male and Female Genital Armature. \Yith 



regard to the male organs of copulation, Kriipelin [374], who 



examined the development of these parts in the Drone, and the 



modifications found in hermaphrodite IVes, is led to the con- 



1 The Anatomy of Invcrtebrated Animals,' London, 1877, p. 433. 



