294 J. JACKSON CLARKE. 



paper, I may add that it arises as a modificatiou of the peri- 

 pheral distributioa of chroraatia already described, but here the 

 particles are rod-shaped, and at certain stages are connected 

 with a central nuclear mass by a beautiful arrangement of 

 achromatic lines, as shown in optical section in fig. 17, where 

 within the host-cell (a) the central nuclear mass {b) is con- 

 nected by achromatic filaments with nuclear rods (c) at the 

 periphery. When once this system of peripheral rods is con- 

 stituted, the subdivision of the parasite by iu-dippings of the 

 surface would appear to be the rule. Fig. 18 shows in a sur- 

 face view an example of such a parasite in which subdivision has 

 proceeded to some extent. Some of the parasites with peri- 

 pheral rods are of considerable size, and show evidence of 

 having changed their form by active movement. The arrange- 

 ment of the deep blue rods is then often most complex ; this is 

 shown in fig. 19, where the large parasite (a) touches the base- 

 ment membrane on one side of a dip between two papillae, and 

 on the other the nucleus of a cell, so suggesting a previous 

 conjugation of two parasites. It also has two dark bodies on 

 its surface near its base. These bodies have an appearance 

 quite similar to the polar bodies referred to in gregariues. 



The general arrangement of chromatin in the swarm-sporing 

 process in Coccid. ovi forme thus agrees with Wolters's de- 

 scription of Klossia, and also with what L. PfeifFer (loc. cit., 

 p. 31) observed in coccidia : " Rasch folgen auf diese 

 anflockerung des primaren Kernes eine Reihe von Kerntheil- 

 ungen wie sie die Bilder in fig. 12 wiedergeben. Die 

 zahlreiche Tochterkerne liegen an dera Mantel der Parasiten 

 Kugel dicht an und oft in schoner geometrischer Anordnung." 

 As far as I am aware, the description of nuclear spindles in 

 coccidia is here given for the first time. What may be the 

 more minute features of the nuclear figures, i.e. with regard to 

 the attraction-spheres, remains yet to be shown. The different 

 behaviour of the parasites with peripheral rods of protoplasm 

 as compared with such as the one shown, fig. 14, may perhaps 

 prove to throw light on direct nuclear division described by 

 Arnold, as compared with the more commonly observed 



