THE HiEMOPLAGELLATES. 225 



regarded as of importance in determining the orientation of the body. It 

 appears, however, that two entirely different processes are concerned. In 

 most cases, if not in all, the clusters which have the flagella pointing 

 centrally are not instances of agglomeration, but of rapid division (see 

 below, Multiplication), where the parasites remain in contact and form large 

 colonies (exs. : T. lewisi, L. and M., Smedley, McN., and others, T. avium 

 and other forms, N. and McN., T. duttoni, Thiroux). On the other 

 hand, even in cultures, true agglomeration clusters, formed by the union of 

 independent parasites, are attached by the non-flagellate end, as in the 

 blood (exs.: T. brucii and T. lewisi, McN., Smedley and others, T 

 av ium, N. and McN., T. paddai, Thiroux). 



These agglomerations differ strikingly from an agglutination of Bacteria, 

 in that the Trypanosomes do not, in the slightest degree, lose their mobility. 

 Each individual continues active movements, its flagellum lashing away at 

 the periphery, and appears to be making strenuous endeavours to escape. 



Another distinctive feature of the phenomenon is that of disagglome- 

 ration. The individuals constituting agglutinated Bacterial clusters are 

 never known to detach themselves, with the resultant dissolution of the 

 mass; and it is for this reason that Laverau and Mesnil use the distinct 

 terms here adopted. Disagglomeration is in consequence of the retention 

 of the power of movement by the parasites during the progress of agglome- 

 ration; thus the Trypanosomes are able to disengage themselves from the 

 cluster, and so to cause the complete break-up of the rosette. Sometimes 

 all the individuals, apparently quite unaltered morphologically, become thus 

 dispersed. At other times the break-up is only partial, a certain number of 

 the more feeble and less mobile parasites remaining together and slowly 

 dying off. Even the larger secondary masses may be thus dissolved. The 

 ability of the Trypanosomes to disagglomerate themselves stands in inverse 

 relation to the strength of the agglomerating serum ; where the agglome- 

 rine is powerful the parasites appear unable to liberate themselves. 



Nut only normal and actively-living Trypanosomes undergo this process, 

 but also parasites which have been stupefied, paralysed, or even killed by 

 chemical reagents or strong doses of a serum become united together. In 

 such cases the Trypanosomes are quite irregularly and indiscriminately 

 arranged, forming more '>r less compact masses of varying shape. Hence 

 Laveran and Mesnil argue that the rosette-formation in typical agglomera- 

 tion is determined solely by the fact that the parasites possess unimpaired 

 mobility, and are actively striving to free themselves, the resulting figure 

 being that of equilibrium. 



Agglomeration does not of itself seem to have any ill effects upon the 

 parasites. Unless disagglomeration occurs the rosettes and masses persist 

 unaltered for some time, the agglomerated individuals retaining their 

 vitality just as well as free individuals in the same surroundings. The 

 only exception is seen in the case of a central rosette, which has served, as 



