296 J. JACKSON CLARKE. 



remains unchanged for a timCj the first indication of karyo- 

 kinetic activity being the separation of hsematoxylin- stained ' 

 chromatin particles joined by achromatic filaments (figs, d, e, 

 and h). When this is the case the unchanged part of the 

 nucleus stains but faintly with hseraatoxylin alone, and when 

 eosin after staining is used assumes a red colour. Sometimes 

 the whole of the nucleus stains deep blue with hsematoxylin 

 at first without any appearance of nuclear filaments. In such 

 cases the nucleus has the appearance shown in fig. /. 

 Irregular mitoses are abundant. Such are shown in figs. 

 / and g. In such mitoses the first portions separated from 

 the main nucleus frequently give the crimson reaction to 

 hsematoxylin. Nothing is more striking than the growth of 

 chromatin in coccidia. In the final multinucleate condition 

 the coccidia possess more than a hundred times the amount of 

 chromatin they had at the commencement of the process. 



Once more reverting to the parasites with peripheral chro- 

 matin rods, it should be observed that in a few cases, which can 

 only be found by patient search, the rods are replaced by fine 

 granules of chromatin, as shown in fig. m. Others of the 

 parasites with peripheral rods appear to break up into an 

 immense number of extremely minute sickles without previous 

 subdivision into segments. Finally, with regard to the seg- 

 mentation of the parasites in the phase marked by peripheral 

 rods of chromatin, it is sometimes seen that the subdivisions 

 possess sickle-shaped outlines like the one seen in optical 

 section in fig. n. It is to be observed, however, that such 

 crescentic segments are not homologous with single sickles, 

 but that each peripheral chromatin rod is the potential nucleus 

 of a spore. 



I would now turn to mention, and it can be but too briefly, 

 L. PfeiflFer's recent work on the Myxo-, Sarco-, and Micro- 

 sporidia.^ In these groups Pfeiffer has added much to bio- 



1 See L. Pfeiffer, ' Protozoen als Krankheitserriger,' 1891, and 'Unter- 

 sucliungen iiber der Krebs,' 1891. 



For a general account, of the Sporozoa and the groups included, together 

 with figures of most of the important forms, see Lankester's ' Zoological 

 Articles' (A. and C. Black), article "Protozoa," 



