OBSERVATIONS ON VARIOUS SPOROZOA. 296 



indirect division of cells. During the subdivision of parasites 

 such as the one shown in fig. 18, when acid hsematoxylin is 

 used alone, bright crimson particles of chromatin are sometimes 

 visible in the interior of the segments. 



The process of nuclear division is not limited to the larger 

 parasites. Some of the smaller (6 — 8 /x) intra-cellular coccidia 

 present nuclei which are dividing indirectly, see PI. 32, fig. 

 21, a. The chromatin is, as a rule, not arranged into chro- 

 mosomes which can be separately distinguished, but is arranged 

 in what under a magnification of 1000 diameters appear to be 

 masses of material which stain purple or blue with hsematoxylin. 

 Such small parasites have no large food-granules, and in propor- 

 tion as the nuclei multiply the cytoplasm and the chromatin 

 increase in amount, giving rise to bodies such as those shown 

 in PI. 32, fig. 21, b, and in PI. 31, fig. 19, b. 



Achromatic filaments are distinctly recognisable in many of 

 the parasites in this modification. The usual termination of 

 the process is the formation of sporogonia which contain 

 several minute nuclear masses embedded in eosin-stainiug 

 protoplasm. The sporogonia subdivide into sickles of the 

 ordinary form. Not infrequently, however, sickles are formed 

 directly, i. e. without a sporogonium stage. Again, the growth 

 of this non-granular form of coccidia may pass beyond the 

 average size (fig. 19, a), and the chromatin becomes minutely 

 subdivided and arranged at the periphery, thus producing the 

 phase marked by peripheral rods, as shown iu PI. 32, fig. 21, d. 

 Returning to the larger granular coccidia, I would here ex- 

 plain that regular mitotic figures, such as PL 31, fig. 12, are 

 extremely few in number. Not so infrequent are typical but 

 slightly irregular spindles, in which all the chromatin of the 

 original nucleus is concerned. Examples are given in PI. 32, 

 fig. 20, a, b, and i. The whole of the chromatin may become 

 active without the formation of a spindle, as shown in figs, c, 

 k, and I. In the parasite represented in fig. k the peripheral 

 collection of chromatin (2) gave a metachromatic (crimson) 

 reaction, whilst the other (1) extremity stained dark blue. In 

 the greater number of the parasites the main mass of the nucleus 



