5 PROTOZOA AND DISEASE 



variola subdivide into minute spore-like bodies without leaving the 

 nucleus, whilst those in the alveolar sarcoma require to escape. 



FIG. 13. CYTORYCTES VARIOLA GUARNIERI. (Copied from the coloured plates 

 illustrating G. N. Calkin's section of ' Studies of the Pathology and on the 

 Etiology of Variola and of Vaccinia,' published in the Journal of Medical 

 Research, 1904.) 



i, A cell from a section of a small-pox lesion : three gemmules are present in the 

 cytoplasm close to the nucleus ; 2., a cell containing an older gemmule in the 

 cytoplasm ; 3, a cell containing a large amoeboid parasite in the cytoplasm ; 

 4, a cell containing an amoeboid parasite in process of gemmule-formation, 

 and, above, a round dense body, probably a microgametocyte ; 5, a cell con- 

 taining an amoeboid parasite in process of gemmule-formation : some of the 

 gemmules are escaping into the cytoplasm ; 6, a cell the nucleus of which 

 contains five spores and three secondary sporoblasts developed from spores : 

 there is one spore in the cytoplasm ; 7, a cell the nucleus of which contains 

 secondary sporoblasts ; 8, a cell the nucleus of which contains a reticular 

 sporoblast, with spores, some of which have escaped from the meshwork ; 

 9, a cell the nucleus of which has been replaced by a large sporoblast, from 

 which some of the spores have escaped into the cytoplasm. 



The results obtained by Bosc 1 agree very closely with those of the 

 American observers. 



1 F. J. Bosc, Cent, fur Bakt.^ 1904, part i., vol. xxxvii., section i. 



