PARTHENOGENESIS IN THE SILK-WORM. 93 



namely, that some caterpillars had united quickly and others 

 more slowly for a moment with the hinder extremity of their 

 body. What is to be thought of this observed union, may be 

 left to every one who is acquainted with the anatomical con- 

 struction of an adult caterpillar, as regards the generative 

 organs. 



A later notice relating to this subject is the assertion of 

 Herold, according to which*, amongst the eggs of an unferti- 

 lized silk-worm moth, some here and there are said to have 

 passed wholly or partially through the same changes which are 

 observed in eggs fertilized by true copulation, whilst most of 

 the eggs remained unaltered. Herold, in his representation of 

 the development of the egg of the silk-worm moth, even di- 

 stinguishes between foetuses developed from fecundated and un- 

 fecundated eggs, of which the former make their escape, whilst 

 the latter always remain in the egg-shell and dief. Although 

 Herold has not stated more precisely what precautions he took 

 to attain the certain conviction that the brood produced from 

 unfertilized eggs was actually derived from virgin females, I 

 nevertheless looked upon the above assertion of Herold with 

 less distrust than upon the before-mentioned examples of sup- 

 posed Parthenogenesis derived from the history of reproduction 

 of the moths, as with the very sluggish silk-worm moths, which 

 do not fly about in the open air, there could be much less 

 probability of the occurrence of a secret and unobserved copu- 

 lation. 



It is remarkable that this spontaneous evolution of the embryo 

 in unfecundated eggs, mentioned byHerold, an observation which 

 might easily be repeated upon the Silk-worms, which are so 

 widely diffused, has hitherto escaped the attention of physio- 

 logists. Herold was the first who furnished an exact and de- 

 tailed description of those changes which may be detected with 

 the lens in a determinate sequence in different silk-worm eggs 

 developing themselves without fecundation. He described first 

 of all, upon the sixth plate of his Disquisitiones^, the consecutive 



* Disquisitiones de animalium vertebris carentium in ovo format ion e. 

 Fasc. ii. 1838, tab. 7- 



T hoc. cit. tab. 7- fig. 31. 



J Disquisitiones, &c. Fasc. ii. 1838. 



