284 REPORT OP THE COMMISSIONER OF AGRICULTURE. 



This discovery of the nymph enables us to say that all the develop- 

 mental phases of Syngamus tracheal** are now known. The only two 

 media which this parasite inhabits during: its entire existence are the 

 water or moist earth during its embryonal condition, and the respira- 

 tory organs of its victim during its nymphal and its adult phase. It is, 

 therefore, developed without the aid of any other medium than the 

 water, corresponding in this respect to the immense majority of vermin- 

 ous parasites. 



