278 PROCEEDINGS OF THE ACADEMY OP [Jline, 



America, for Sporozoan parasites. In the list of Sporozoa and their 

 hosts recently compiled by Minchin,^ Bufo lentiginosus is given as the 

 host of one known species, Leptotheca (Chloromyxum) ohlmacheri, a 

 Myxosporidian which was first described in 1893 by Ohlmacher,^ who 

 found it in the renal tubules. In but two other instances have Sporo- 

 zoan parasites been found in any species of Bufo, and comparatively 

 few cases of infection have been recorded for the different species of 

 Rana. As presumably the amphibians are as subject to parasitic 

 infection as are the other vertebrates, they would seem to afford a 

 profitable field of investigation for the discovery of new Sporozoan 

 forms. 



Explanation of Plate XXII. 



All figures were drawn with the aid of a camera lucida under a Zeiss apoc. obj. 

 1.5 mm. Oc. 8. 



Fig. 1. — ^The young parasite and its division stages. 

 Fig. 2. — Trophozoite at the beginning of the growth period. 

 Fig. 3. — Mitotic division of the nuclei of the young trophozoite. 

 Fig. 4. — Formation of the cyst wall around the trophozoite. 

 Fig. 5. — Mature trophozoite before its division into spores. 

 Fig. 6. — Division of tlie trophozoite into spores. 

 Fig. 7. — Cyst containing young spores. 



Figs. 8-16. — Stages in the development of spores according to Type I. 

 Figs. 17-23. — Stages in the development of spores according to Type II. 

 Figs. 24-31. — Spores showing apparent deviations from the usual modes of 

 development. 



^ Minchin, E. A., Sporozoa: A Treatise on Zoology, edited bv E. Ra}' Lancaster, 

 Pt. I, 1903. 



^ Olilmacher, A. P., Myxosporidia in the Common Toad, with Preliminary 

 Observations on the Chromophilis Substance in the Spore, Journ. Amer. Med. 

 Assoc, Vol. XX, 1893. 



