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exiftence of a medullary thread in the 

 heads of infecfs, but we never could dif- 

 cover it to be organized ; hence the 

 hippobofca equina, or horfe fly, will 

 live, run, nay even copulate, after be- 

 ing deprivedof its head ; to fay nothing 

 of many otherswhich are capable of liv- 

 ing a long while in the fame fituation. 

 As they are not furnifhed with ears, we 

 apprehend them incapable of hearing ; 

 as we can no more conceive that fenfe 

 to exiff. without ears, than vifion with- 

 out eyes. They are neverthelefs fuf- 

 ceptible of any fhrill or loud noife, as 

 well as fifhes, but in a manner different 

 frorh that of hearing. We are alfb du- 

 bious iftheyhave the fenfeof fmell, no 

 organ being found in them adapted to 

 that purpofe ; they neverthelefs per- 

 ceive agreeable and fetid effluvia, but 

 in a manner wholly unknown to us. 

 Many iufects have no tongue, nor make 



