MYXIDIUM LIEBERKUHNI BUTSCHLI. 375 



3. FINDINGS IN STAINED PREPARATIONS. 



The material was fixed in hot Schaudinn's fluid and stained 

 with either borax-carmine, Delafield's haematoxylin, or Giemsa's 

 stain. For the method used in applying the latter see Mavor 

 (19160). 



The myxosporidia were found to contain nuclei of two sizes; 

 larger nuclei measuring 2.5 /j. in diameter and smaller nuclei 

 1.2 /JL in diameter. No essential differences of structure were 

 observed in these nuclei and no difference could be observed in 

 their reaction to Giemsa's stain as was found by the author to 

 be the case in the nuclei of Ceratomyxa acadensis (Mavor, 19160). 

 There are two kinds of granules evident in preparations stained 

 with Giemsa's stain and they show the same reactions as de- 

 scribed by the author in his previous paper (Mavor, 1916^). 



The sporogenesis follows in its later stages the method de- 

 scribed for Myxobolus pfeifferi by Keysselitz (1908). The sporo- 

 plasm of the fully formed spore contains two nuclei. 



4. THE SIGNIFICANCE OF THE OCCURRENCE OF MYXIDIUM 



LIEBERKUHNI IN AMERICA. 



There can be little doubt that the myxosporidia of fishes are 

 without an intermediate host. Their life-cycle consists of a 

 period spent in the body of the host-fish alternating with a period 

 during which the spores are free in the water or are passing 

 unaffected through the digestive tract of some other aquatic 

 animal. There are three ways in which their geographical dis- 

 tribution may be extended; (i) the spores may be carried in 

 currents of water, (2) the spores may be carried in the digestive 

 tract of aquatic animals, (3) all stages may be carried by the 

 host-fish and accompany it in its wanderings. That the spores 

 could be carried from the fresh water of one continent to the 

 fresh water of another continent by either of the first two methods 

 seems unlikely. It would seem therefore probable that Myxid- 

 ium lieberkiihni has followed in its distribution the wanderings of 

 its host Lucius lucius. 



Lucius lucius is a very old species. " Remains of the common 

 pike occur in abundance in quaternary deposits" (Gunther, 

 1880, p. 624). Furthermore, not only the genus but the family, 



