BLOOD-PAEASITES OF FISHES OCCUREING AT ROVIGNO. 147 



perhaps, by Twort ; in the case of films stained Avith iron- 

 haematoxylin, the stain must be very well extracted, or else 

 the whole karyosomatic mass is too heavily stained for them 

 to be made out. This is evident by comparing our various 

 figures. Fi'om ynany of the figures in the above-mentioned 

 papers we should say that extraction in those cases had not 

 been carried far enough for this purpose. For instance, in 

 most of the resting nuclei of the various trypanosomes 

 drawn by Rosenbusch (I.e.), the karyosome is too dark to 

 show the central granule. 



There can be no doubt that this granule or centriole is the 

 intra-nuclear centrosome first described by Schaudinn in the 

 trophonucleus of his trypanosome in the little owl. It is also 

 evident that it acts as a division-centre, and forms an intra- 

 nuclear spindle at the commencement of nuclear division. 

 This phase is well shown by several of Rosenbusch's figures. 

 Again, to compare a dividing stage described from a Giemsa- 

 stained preparation, Minchin, in his account of T. gray i (11), 

 figures an intra-nuclear granule at each end of the spindle 

 still connecting two daughter-nuclei, immediately after division 

 has taken place. Hence this intra-nuclear centrosome^ is 

 doubtless a regular constituent of the trophonucleus of a 

 Trypanosome. 



It will be noticed from our figures that, in the Griemsa- 

 stained preparations of T. raiee; the red-stained part of the 

 nucleus is fairly uniform or homogeneous in appearance. It 

 is more usual, however, for the nucleus of trypanosomes 

 stained by the Romanowsky method to appear granular in 

 structure, apparently consisting of small or medium-sized 

 granules in close contact, and forming a compact mass (cf . 

 the selected figures, either in the article on "Trypanosomes" in 

 Lankester's ' Treatise on Zoology,' or in Liihe's article in 

 Mense's ' Handbuch der Tropenkrankheiten'). This appear- 



' Moore and Breinl (14a) use the term "intra-nuclear centrosome" 

 in a diiferent sense from ourselves, namely, for the entire central body 

 which we regard as the karyosome. They do not seem to have dis- 

 tinguished at all the centriole contained in the karyosome. 



