THE HAEMOFLAGELLATES 



(b) Habitat and Effects on Ho.<f. 



1. Relation to the Invertebrate Host. Schaudinn, in his work on 

 the parasites of an owl (Athene noctua) (I.e.), has described in full 

 the distribution and course of development of Trypanosomes in the 

 body of a gnat (Culex pipiens). Although, as is pointed out below 

 (see under "Life-Cycle"), it is now disputed how far Schaudinn's 

 description actually relates to Avian Trypanosomes, the great 

 interest excited by this author's work renders a brief abstract of 

 his account necessary. 



prov. 

 oes. 



Fie. 4. 



Diagrammatical longitudinal section through Culex pipiens to show the distribution of thff 

 parasites. The arrows indicate the direction of their movement, the cTusters of stars the place* 

 of agglomeration, u.l, upper lip ; LI, lower lip; tip, hypopharynx ; ph, pharynx; s.g, salivary 

 gland ; ocs, oesophagus ; o.d, oesophageal diverticula (gas reservoirs) ; prov, proventriculus ; 

 st, stomach ; m.t, Malpighian tubes ; c, junction of ileum and colon ; aort, aorta. (After 

 Schaudinn.) 



The distribution of the parasites 1 is intimately connected with the 

 process of digestion. Towards the end of the digestion of the imbibed 

 blood, the Trypanosomes, after a period of multiplication, enter upon ;v 

 resting phase, and are found either attached to or between the epithelial 

 cells. After a second meal another multiplicative period occurs, and the 

 parasites gradually collect in the anterior part of the stomach, where the 

 nutriment remains longest unabsorbed. Here (Fig. 4, prov) the organisms 

 begin to cluster in large numbers, being able to penetrate the delicate 

 surface of the layer of invaginated oesophageal epithelium in this region. 

 Finally, there is an enormous accumulation of the Trypanosomes at this 

 place, all arranged in rows and in a resting condition. The next inflow 



1 Tliis summary relates to the first of the two parasites described by Schauiliim, 

 Trypanomorptia (Trypanosoma} noctnae. 



