THE ILEMOSPORIDIA 391 



resting intracorpuscular diurnal phase of a trypanosome which at night 

 developed a locomotor apparatus, became free from the blood- corpuscle, and 

 swam freely in the plasma ; in the morning the trypanosome penetrated into 

 a corpuscle, lost its locomotor apparatus again, and became a halteridium. 

 Male, female and indifferent forms were distinguished. The smallest in- 

 different forms went through a six-day development and growth, in the 

 corpuscle as a halteridium by day, free in the plasma, as a trypanosome by 

 night, until full grown ; then they multiplied rapidly by repeated fission to 

 produce trypanosomes of the smallest size. These young forms might grow 

 up into indifferent forms in their turn, or might become male or female forms ; 

 in the latter event their development was slower, and in its later stages the 

 parasite lost the power of forming a locomotor apparatus or of leaving the 

 corpuscle. Thus arose the adult male and female halteridia, which, in order 

 to continue their development, required to be taken up by a gnat, Culev 

 pipiens. In the stomach of the gnat the parasites formed gametes which 

 copulated and produced zygotes in the well-known manner. Each ookinete, 

 according to Schaudinn, formed a locomotor apparatus (see Fig. 30, p. 59) and 

 either became a trypanosome which might be of female or indifferent type, 

 or gave rise to several trypanosomes in the male sex. The trypanosomes 

 of each type multiplied in the digestive tract of the gnat to produce a swarm 

 of trimorphic individuals, but no further copulation of the male and female 

 forms occurred or could occur (Schaudinn, 132, p. 401). Ultimately, after 

 complicated migrations, the trypanosomes were inoculated by the gnat into 

 the owl again ; the male and indifferent forms passed through the proboscis, 

 but the female forms were too bulky to do so, and, as the male forms were 

 stated to die off in the blood, there was effective inoculation of indifferent 

 forms only, which start on the cycle of development already described. 



These remarkable statements, the origin and significance of which have 

 been, for the last seven years, a veritable riddle of the sphinx, have met with 

 general scepticism except from a few devoted partisans, who have been 

 striving continually to find corroborative evidence for Schauclinn's theories, 

 in spite of the mass of evidence to the contrary that has been steadily accu- 

 mulating. Recently Mayer (685) has affirmed that in owl's blood containing 

 only halteridia, kept under observation in hanging drops under the micro- 

 scope, trypanosomes make their appearance which could only have come 

 there by transformation of halteridia. These experiments are supposed to 

 prove conclusively one part, at least, of Schaudinn's statements namely, 

 that the halteridia are merely intracorpuscular stages of trypanosomes. 



Against Schaudinn's views, on the other hand, two principal objections, 

 out of many, may be urged : 



First, that the development of Hcemoproteus columbce, as made known by 

 the Sergent brothers and by Aragao, is of a totally different type to that 

 described by Schaudinn. ; it comprises no trypanosome-phases at any point 

 of the life-cycle, and the invertebrate host is not a gnat, but a biting fly of an 

 altogether different kind. To meet this objection, Mayer proposes to restrict 

 the name Hcemoproteus to forms which develop after the manner of H. columbce, 

 and to revive the name Halteridium (in italics and with an initial capital 

 letter) for parasites that, on the Schaudinnian theory, are really trypanosomes. 



Secondly, that the small trypanosomes of Athene noctua are connected 

 by every possible transitional form with the largest found in the same bird, 

 and there is every reason to suppose that in this case, as in other birds or 

 vertebrates of all classes, they are all merely forms of one polymorphic try- 

 panosome (Minchin and Woodcock, 42). 



It may be added that the whole mystery receives a complete solution on a 

 simple supposition namely, that the trypanosome of the Little Owl, like other 

 known species of trypanosomes (see p. 308), has intracorpuscular forms 

 which have been confused with the true halterida ; on such an assumption, 

 so eminent an investigator as Schaudinn can be acquitted of having made 

 what would appear at first sight to be a gross error of observation, and Mayer's 

 observations are easily explained. Mayer seems, in fact, to have figured 



