194 H. M. WOODCOCK. 



indeed, limited to them. Hence these forms largely pre- 

 dominate in number, and many oi: them, especially small ones 

 resulting towards the end of a multiplication-period, go to 

 swell the ranks of male and female parasites. Correspond- 

 ingly, while all the types can pass into the blood of the owl, 

 the great majority of those which do so are indifferent forms. 

 Before considering the Trypanosomes in the blood of the 

 bird, however, there is one very important characteristic of 

 the parasites which must be mentioned. 



Agglomeration. — In common with many other Trypano- 

 somes, Trypanomorpha noctuae possesses the capacity 

 for agglomeration. Agglomeration takes place upon the 

 advent of unfavourable conditions (e. g. a period of hunger) 



Fig. 12. — Cluster of agglomerated male Trypanosomes in the 

 intestine of the gnat. (After Schaudinn.) 



in the environment of the parasites, and all three types 

 possess this faculty ; it occurs to the greatest extent, how- 

 ever, among the male and indifferent forms. Agglomera- 

 tion consists in the grouping or union together of the 

 Trypanosomes around a common centre ; this leads to the 

 formation of rosette-like clusters (fig. 12), or even large 

 masses. The parasites are invariably attached by the same 

 end, which is, in the case of Trypanomorpha, the anterior, 

 flagellate end ; so that all the flagella are directed inwards, 

 towards the centre of the rosette. If the unfavourable 

 conditions continue the parasites remain in this agglomerated 

 state until they die and disintegrate. If, however, a favour- 

 able change suddenly sets in, the Trypanosomes are able to 

 undergo the inverse process, namely, disagglomeration. 



