622 TRICHOMYCETES, ACTINOMYCETES, HYPHOMYCETES 
Rats are quite susceptible to inoculation with pus from lesions or 
from cultures. The disease may follow an acute or a chronic course, 
but the cutaneous nodules are not regularly produced in this animal 
—otherwise the lesions are fairly typical. In the acute disease the 
animal usually dies within two weeks, frequently in consequence of a 
degeneration of the parenchyma of the kidney. The organism may be 
recovered from the blood stream or the kidneys— a true sporotrichon 
septicemia. In the chronic type of the disease the mold localizes and 
results in the formation of multiple abscesses in the internal organs 
and especially in the testes. Intraperitoneal injections usually lead 
to the appearance of small nodules in the testes and internal organs 
which may remain discrete or become confluent, with central necrosis 
and suppuration. They resemble miliary tubercles superficially. 
Microscopically the relatively large oval spores, but not the mycelia 
are found. The disease appears to occur spontaneously in rats, espe- 
cially the testicular type. It is also common in horses.^ 
The serum from cases of sporotrichosis frequently agglutinates the 
spores of the organism (best obtained by grinding cultures to dryness 
in a sterile mortar, then diluting with salt solution and filtering through 
filter paper) in dilution from 1 to 200 even 1 to 1000. The sera of 
normal individuals possesses no agglutinating power for the organism. 
Actinomycotic serum may agglutinate with the organism in dilutions 
as great as 1 to 50, suggesting common group agglutinins for both 
organisms. Complement-fixation is apparently not specific. 
SACCHAROMYCETES. 
The Saccharomycetes or yeasts are especially characterized by their 
method of multiplication. Unlike the Bacteriaceae, which reproduce 
by transverse fission, the resulting cells being of equal size, the yeasts 
reproduce by budding. A yeast cell about to reproduce sends out an 
evagination or bud, which is first visible as a minute enlargement on 
the surface of the parent organism. This gradually increases in size, 
still maintaining an ovoid shape and remaining adherent by a small 
isthmus until it reaches approximately the size of the original cell. 
The isthmus then is broken, continuity between the two cells is inter- 
rupted and the fully mature individual reproduces in like manner. 
It is not uncommon to find budding in the daughter cell before it 
severs its connection with the mother cell, if the environmental 
conditions are favorable for rapid growth. Many yeasts form highly 
refractile bodies— ascospores— within their cytoplasm when environ- 
mental conditions become unfavorable for further development and, 
unlike the bacteria, each yeast commonly produces more than 1 spore, 
usually 2, 3 or 4, but rarely or never more than 4. The ascospore 
is outlined by a doubly contoured membrane and usually it remains 
I Meyer: Jour. Am. Med. Assn., 1915, 65, 579, 
