224 n. M. WOODCOCK. 



tive behaviour o£ different sera, tlie reader is referred to the works of 

 Laveran and Mesnil (40, 48 and 56), Lignieres (71), Brunipt and AVurtz 

 (12), Thiroux (114, 115), and others. 



Agglomeration commences by two Trjpanosomes coming together and 

 joining (figs. 19, 20 a). In all cases in which the phenomenon has yet been 

 witnessed in a natural (as opposed to an artificial') medium, a particular 

 form of Trjpanosome always unites by the same end. In Trypano- 

 morpha, as already described, the parasites join by the anterior, 

 flagellate end. Agglomeration has not, up till now, been observed in 

 Trypanoplasma, but there can be little doubt that, if it occurs, it will be 

 found to take place there also by the anterior end. On the other hand, in 

 all the species of Trypanosoma (including T. ziemanni) for which the 

 occurrence has been so far described, the parasites unite by the non- 

 flagellate end. The union may sometimes remain only binary. In 

 other cases agglomeration is lapid and progressive, the union of two para- 

 sites being quickly followed by that of many otliers around the same 

 centre, the whole forming a "multiple union" or rosette (fig. 20b). 

 Such a rosette is termed a primary agglomeration, and may be composed of 

 as many as one hundred individuals. In many cases, especially where the 

 agglomerinc is specific and very powerful, the rosettes themselves become 

 grouped togetlier to form large tangled masses known as secondary agglome- 

 rations. 



In "cultures," rosettes or clusters are frequently observed in which the 

 arrangement of the parasites is different, and may vary even in the same 

 species ; that is to say, in some cases the Trypanosomes have their flagella 

 at the periphery, while in others they are all attached by the flagella, which 

 are directed towards the centre (fig. 29). This has been considered as 

 indicating that the end by which agglomeration takes place cannot be 



' Much attention has lately been paid — particularly by Novy and McNeal 

 (79—81), Smedley (107), and Thiroux (I.e.)— to the cultivation of dift'erent 

 Trypanosomes in artificial media, in' the same way in which cultures of 

 Bacteria are obtained. The writer does not propose to give the details 

 of the composition of the various media tried, nor to discuss the technique 

 and the great (but quite natural !) difficulty experienced in persuading the 

 parasites to live and thrive [?]. For it cannot be too strongly insisted that 

 this is not a zoological method of research, and that the results obtained do 

 not add to our knowledge of the parasite's real life-history and biology, but 

 must be accepted as normal phases only with the greatest caution. It is 

 not merely a question of obtaining a " pure culture," as Novy and McNeal 

 consider: the Trypanosomes are not Bacteria. As will be seen later, some 

 of the opinions to which the authors are led, as a result of practically 

 limiting themselves to this method of investigation, are — to say the least — 

 not generally accepted. 



