18G4.] 573 



babies, and tadpoles, and larvfe, should propagate their species, but it 

 is not at all contrary to experience that human eyes should be deceived. 

 The well-known case of Aphis is not a case in point. It is not the larva 

 of the Aphis that generates by parthenogenesis, but an adult, although 

 wingless, dimorphous form of the winged imago of the 9 Aphis. The 

 whole question hinges entirely upon the presence of the "breast-bone" 

 in these young larvje, which Wagner asserts were produced from the 

 bodies of Cecidomtjia larvas. If they had that " breast-bone," they 

 were Cecidomyia ; if they had not, they were beyond all question ChaJ- 

 cididse. or Proctotrupidse,. Yet, important as this point is, Wagner does 

 not appear to have paid enough attention to it, to think it worth while 

 to testify explicitly on the subject! 



Since the above was written. Baron Osten Sacken has been kind 

 enough to inform me that " Wagner's discovery is now very well known 

 in Germany, and has been fully confimed by several observers." What 

 is the entomological status of those observers, and how far their evi- 

 dence is trustworthy, is not specified. They may be scientific tyros, or 

 they may be good general Naturalists but very poor Entomologists, or 

 they may be men of high standing and credit in the entomological 

 world. For my own part, I would not believe in an anomaly which not 

 only contradicts the known generative economy of all Vertebrate and An- 

 nulate Animals, but which also runs counter to what I know, from close 

 and long continued observation, to be the generative economy of several 

 other species of the same genus, viz : the Gall-gnats of the Willow, un- 

 less I saw it at least a dozen times with my own eyes, or unless it was 

 vouched for by at least a dozen good and experienced Entomologists. 

 It is utterly incredible that certain species of Cecidomyia should pro- 

 create in the larva state, while certain other species procreate in the 

 normal manner. Now I know that the Cecidomyia of the Willow pro- 

 create in the normal manner; and therefore, firmly believe that all other 

 Cecidomyia procreate in that manner. To believe to the contrary seems 

 to me to require as much faith as to believe that certain Species of the 

 genus Felis are viviparous, and certain other species of the same genus 

 lay eggs and hatch them out like a bird ; or, that certain Gallinaceous 

 birds feed, when first hatched out, upon vegetable substances, and cer- 

 tain others suck the teats of their mothers like so many Mammals. 



The Russian naturalist, however, and the unnamed German observers 



