XI] HALTERIDIUM OF ATHENE NOCTUA 2OI 



into trypanosomes which again might be either female or 

 indifferent, or divide up into a large number of male forms. 

 Ultimately the indifferent and male trypanosomes were inocu- 

 lated back again into an owl ; the female trypanosomes being 

 too bulky could not pass through the proboscis of the gnat, and 

 as the male forms soon died out in the blood the new infection 

 was started by the indifferent trypanosomes. 



This extraordinary account of the life-cycle of the parasite 

 of the Little Owl has been the subject of much discussion 

 during the past few years. 



Mayer has brought forward evidence in support of one of 

 Schaudinn's statements, for he found that when owl's blood 

 containing only halteridia was kept in hanging drops under 

 the microscope, eventually trypanosomes made their appearance 

 and these could only have come there by the transformation of 

 the halteridia. 



On the other hand no other confirmation of the life-cycle 

 has hitherto been published, whilst there are many serious 

 objections to it. In the first place the careful researches of 

 Minchin and Woodcock, who worked at- Rovigno, the place 

 where Schaudinn made his observations, have shewn that in 

 the blood of Athene noctua there is every stage between the 

 small trypanosomes and the large ones, and there is every 

 reason to suppose that in this case, as in many other verte- 

 brates, these are all merely forms of one polymorphic try- 

 panosome. 



Further the development of Hcemoproteus columbce, the 

 halteridium of the pigeon (v. Chapter XXIII), is of a totally 

 different kind, as the transmitting host is not a mosquito and 

 moreover the development does not include any trypanosome 

 phases. 



Minchin suggests a solution of the difficulty by supposing 

 that the trypanosome of the Little Owl, like other known 

 species of trypanosomes, has intracorpuscular forms which 

 have been confused with true halteridia. 



With regard to Schaudinn's account of the life-cycle of 

 the Leucocytozoon there is not the slightest doubt that no 

 relation exists between this parasite and the spirochaetes and 



