170 THE MICHIGAN ACADEMY OF SCIENCE. 



have regarded as the spores produced by the organism. However, even 

 these probably are not true spores, as indicated by the thermal death 

 point of the cultures. The mycelium may be made up of interlaced 

 filaments, or may appear as wavy, somewhat parallel strands, suggesting 

 a horse's mane; in old cultures, a marked fragmentation of the mycelium 

 may be observed. Club-shaped enlargements of the ends of the fila- 

 ments and of short lateral branches are frequently encountered, particu- 

 larily in old cultures. These frequently show what may be termed polar 

 bodies and transverse bands, resembling in appearance the club-shaped 

 forms of B. diphtherias The width of the mycelium is not constant, and 

 may, in places, assume a diameter many times that of the neighboring 

 filaments and portions of the same filament. In general, the width is 

 about 0.4 of a micron. The broadened filaments may be thickly studded 

 with the above mentioned coccules. scattered irregularly, or the whole 

 diameter nmy be taken up by the solid, deeply staining protoplasm. I 

 have not observed thus far in any of the preparations examined, fruit 

 hyphae containing rows of conid^a. The morphology of the organism on 

 the various media has not yet been systematically worked out. 



Cover-glass pre])arations stain readily with the ordinary dyes and 

 also take Gram's stain. On applying Ziehl-Neelsen's solution, the organ- 

 ism is found to be alcohol-fast but not acid-resisting. 



Thermal death point determinations show that sporulating cultures re- 

 sist 45° perfectly for sixt}^ minutes, but are destroyed by 65° in less than 

 five minutes. 



The cultures grow best in the presence of air, but can be grown in 

 the absence of oxygen. However, growth under the latter condition is 

 sloAv, and pigment production is decreased. The anaerobic conditions 

 employed were displacement of the air by hydrogen, and the absorption 

 of oxygen by the pyrogallic method. 



.Growth occurs at room temperature, at 22°, and at 37°, but best at 

 37°. 



The pigment is a brilliant orange on almost all the media employed. 

 It is evidently insoluble in alcohol, chloroform, ether or Avater. In one 

 instance it was observed to diffuse slightly through a liquefied gelatin. 



On agar plates the colonies are round, raised, moist, hard and of a 

 brilliant orange color. Microscopically, a deep yellow center is seen, sur- 

 rounded by a lighter, less dense zone of branching filaments, producing 

 a ray appearance. In young colonies, the inner zone cannot be dif- 

 ferentiated, and the colony appears as a ball of interwoven filaments, 

 with peripheral radiations. 



The growth on inclined agar consists of round, elevated, moist colonies, 

 of an intense orange color, and firmly implanted in the medium. In 

 order to obtain growth, the implanted nmterial must be rubbed strongly 

 into the inclined surface of the agar. The growth appears at first 

 as minute, pin-head, roundish elevations of a pale orange color. Deep 

 colonies, closely resembling these, also occnr. The surface colonies grad- 

 ually increase in size, assuming a somewhat deeper pigment, and during 

 the growth, adjacent colonies may coalesce, forming a circumscribed, 

 wrinkled growth. In no instance have I observed a chalky efflorescence, 

 due to air-hypha?, covering the surface of the colonies, as has been de- 

 scribed for many streptothrices. Descending filaments are probably the 

 ■cause of the firm implantation of the colonies in the medium. The 



