SPOROZOA. LEPTOTHRIX: ACTINOMYCES 41 



parasites similar to the plasmodia, with which they have been associated 

 to form a new group, the Haemosporidia. Their complete life-histories 

 are unknown, and clinical descriptions are wanting. The best known 

 species is Drepanidium ranae, from the blood of the frog. Formerly 

 described as a Cytozoon, it was at one time regarded with great interest, as 

 it was thought to be not a parasite, but a tissue element of the frog. Its 

 parasitic nature is now, however, generally recognized. There may be 

 mentioned here the numerous kinds of parasitic micro-organisms, which are 

 classed together as Sporozoa (Gregarinae, Coccidia, Sarcosporidid). They 

 are all very imperfectly known, as it has not been possible to study them in 

 pure cultures. 



Among the organisms that have been at different times reckoned as 

 bacteria is a small group of fungi, some of them pathogenic, known as 

 Streptothrix. They form felted mycelial masses of extremely delicate 

 branched hyphae. In pure cultures they are in some cases sterile, but in 

 others bear fructifications in the form of conidia, either single or in short 

 chains, arising from the hyphae, resembling in this respect the lowest fungi 

 (Haplotnycetes, Hyphomycetes), to which they undoubtedly belong. They 

 have nothing in common with the bacteria. 



There seems to be reason to think that the genus Streptothrix (Oospore?) 

 will meet the same fate as the so-called Leptomitus. Leptomitus was the 

 name formerly given to all and every kind of filamentous fungal growth 

 that made its appearance in neglected solutions in druggists' shops, in ink, 

 &c, &c. We now know that these are not the complete forms of any specific 

 fungus, but merely the sterile mycelia of various moulds growing slowly and 

 abnormally in more or less unsuitable media. There can be little doubt 

 that many growths now termed streptothrix will in like manner turn out 

 to belong to well-known genera of hyphomycetes, which will complete their 

 life-history when planted on suitable media. Even the best known species 

 of Streptothrix, 5. actinomyces (Actinomyces bovis), the ray-fungus, does not 

 seem to run through its entire cycle of growth in our artificial cultures. 

 Its thallus consists of branched filaments made up of cylindrical cells just as 

 in an ordinary mould-fungus, and it grows upon agar or blood-serum in the 

 form of thick wrinkled mats with a ' pile '-like surface. This velvety coat is 

 due to the aerial hyphae which rise vertically from the mycelium and break 

 up at their free ends into rounded cells like conidia. Whether these really 

 are spores or not remains to be proved. 



The ray-fungus gives rise in cattle, and sometimes in man, to peculiar 

 hard tumours, commonly in the tongue or jaw ('lumpy jaw '). These tumours 

 suppurate sooner or later and often spread to other parts. Infection seems 

 to be effected by the agency of sharp awns of rye and other cereals on which 

 the fungus probably grows as a mould. They pierce the mucous membrane 

 of the mouth, and carry the spores into the subcutaneous tissue. Attempts to 



