THE ILEMOSPORIDIA 381 



structure, a compact mass of chromatin or karyosome contained 

 in a vacuole-like space in other words, a protokaryon of the simplest 

 type (compare Breinl and Kindle, 730). The remarkable form 

 Nicollia quadrigemina has an oval nucleus at the blunt end of the 

 body, with two karyosomes, a larger one placed close to the surface, 

 and a smaller one nearly at the centre of the pear-shaped body 

 (Nicolle, 746). 



With the unreliable method so much in vogue until quite recently, of 

 making preparations by drying blood-smears and staining them with the 

 Ronianowsky stain, the nucleus may show various appearances about which 

 much has been written, and which cannot be interpreted with certainty until 

 they have been examined by better cytological methods. In such prepara- 

 tions the appearance is usually presented of a deeply-stained karyosome 

 lying at the edge of, or near to, a diffuse, more or less irregular chroniatin- 

 mass ; or the nucleus as a whole may appear as an evenly-stained mass lying 

 usually at one end of the body in bacillary forms, or near the rounded ex- 

 tremity in the pear-shaped forms. In other cases, in addition to the principal 

 clironiatinic mass, some specimens may exhibit a grain or dot, which from its 

 staining reactions appears to be chromatin. Many efforts have been made 

 to establish on this slender basis a theory of nuclear dimorphism for piro- 

 plasms, and to interpret the second grain as a kinetonucleus ; but it bears no 

 resemblance to any such body in its structural and cytological relations, and is 

 inconstant in its occurrence, being entirely absent as a general rule. 



A question much discussed is that of the occurrence of flagellated forms of 

 piroplasms in the blood of the vertebrate host. In a few rare cases, in parasites 

 preserved by the defective method mentioned in the last paragraph, irregular 

 streaks of substance similar to chromatin in its staining properties have been 

 seen extending from the karyosome even some way be3 T ond the body of the 

 parasite (Fantham, 735; Kinoshita, 741), and these appearances have been 

 interpreted as flagella ; but the published figures of these structures do not 

 in the least favour any such interpretation. Kinoshita suggests that the 

 " flagella " figured by him may represent formation of microgametes. Of 

 more value are the observations of Nuttall and Graham-Smith (748) on the 

 living parasites. They observed that a pear-shaped parasite, when free in 

 the blood- plasma, is capable of moving very rapidly, with the blunt end 

 forwards, while the posterior pointed end exhibits active vibrations which they 

 compare to those of a fish's tail. In some cases the hinder end was observed 

 to be prolonged into a flagellum-like process. The authors cited explain the 

 absence of flagellated forms in permanent blood- preparations by supposing that 

 the flagellum becomes retracted when preserved ; if so, it is a structure of a 

 very different kind to a true flagellum, such as that of a trypanosome, and its 

 relations to the progression of the parasite also differ. 



Breinl and Hindle (730) have figured biflagellate organisms from the blood 

 of dogs dying from piroplasrnosis. The flagellates in question were of transi- 

 tory appearance, and were only found in the blood of the dog the day before 

 its death. The authors interpret these forms as a phase of the piroplasni ; 

 but a consideration of the figures given, and of the circumstances under which 

 the flagellates were found, leave hardly any doubt but that the forms seen 

 were intestinal flagellates, Bodo or Prowazekia sp., which, in the pathological 

 condition of the host, had passed into the blood (see p. 258). 



The development of the parasite in the vertebrate host appears 

 to consist solely of multiplication by fission (Figs. 160, 161), usually 

 either binary or quadruple, within the corpuscle ; though the 

 presence of the annular forms, apparently representing young 



