26 



MASS. EXPERIMENT STATION BULLETIN 319 



were incubated at 37° C, and at frequent intervals meat extract peptone agar 

 plates were streaked. The flasks were incubated at 37° C. for three weeks and at 

 room temperature for 11 weeks. While incubating at the higher temperature a 

 heavy scum formation was observed in the flask inoculated with Strain I. Upon 

 agitation of the flask the scum would gravitate to the bottom in floccules. Ring 

 formation was observed in the flask containing Strain II. Heavier growth occurred 

 in the 5 per cent peptone solution than in the meat extract peptone broth. 

 Streaked plates made from the peptone and the broth cultures did not reveal a 

 colony picture which differed from the original. Strains I and II, which are older 

 than Strain IV and are not entirely normal, seemed to thrive better in the peptone 

 solution than Strain IV. The pH increased in each instance during the 14 weeks 

 period. 



Table 4.- 



-Remarks concerning colonial and cellular morphology of 

 isolated variants. 



Original Variant 

 Strain No. 



No. 



Culture 

 Medium* 



Colonial and Cellular Morphology 



IV 



IV 



XII 



XII 



XIII 



IV-a 



XHI-a 



P. A. 



IV-b P. A. 



XH-a P. A. 



Xll-b L. A. 



L. A. 



Experiment No. I 



Small irregular colonies at 24 hours of age; older colonies ap- 

 pear more round and entire; average size of former approximately 

 .1 mm., larger colonies .5 — .75 mm. in diameter. Surface smooth, 

 slightly convex and glistening. Structure coarsely granular to 

 filamentous. Cells — many bizarre forms including thick filament- 

 ous, coccoid and club-shaped. Some contained granules. Typical 

 cells were present. See Figures 3, 4, 5, 6, and 7. After frequent 

 transfer, a colony type was produced as shown in Figure 8, with 

 a less pleomorphic cellular morphology. 



Colonial and cellular morphology at first similar to IV-a. Later 

 a colony type developed which moved in mass, exhibited small 

 projections, was dome-shaped and opaque. See Figure 9. Cellular 

 forms slightly pleomorphic. 



Experiment No. II 



Colony has crenated edge, thin periphery, and is almost trans- 

 parent; markedly convoluted. The interior is raised, level, slightly 

 rough, dull, and opaque. Cellular forms highly pleomorphic. See 

 Figures 10 and 11. 



Colonial and cellular features similar to I-a. 



Colony with undulating edge, semi-dome shape, and prominent 

 central portion with shallow grooves winding outward. Dull in 

 appearance. See Figure 12. Cells markedly pleomorphic, including 

 cells of various lengths, club-shaped and dumb-bell forms, and 

 some filamentous types. 



Colony irregular in outline, periphery flat and thin; central por- 

 tion raised and opaque; surface rough, due to numerous shallow 

 valleys and ridtres; brittle consistency. Size may vary from 7 mm. 

 to less. See Figure 13. Cells slightly pleomorphic, short thicK rods, 

 [ approaching coccoid type. 

 Colony type similar to VIH-a, but cells slightly more pleomorphic. 



I Colony has undulating edge, flat surface varying in roughness 

 and dull in appearance. Some colonies are markedl) convoluted 

 with thin periphery. Isolated colonies may attain a diameter of 

 2 cm. See Figures 14, 15, and 16. Cells are markedly pleomorphic, 

 (long and thick filaments. Some cells are short. 



(Colony is smooth, mound-shaped, undulating in outline, opaque, 

 and moves in mass. See Figure 17. Cells resemble normal, but a 

 few odd shapes and filamentous forms are present. 



Colony has dentated edge and very thin periphery which is 



markedly convoluted, striated and tenacious. Central portion 



'. is raised, dense, and faintly convoluted. See Figure 18. Cells in ihe 



outer portion entirely filamentous, while cells from central portion 



{ approach the normal with slight variation. See Figures 10 and 20, 



Colony has irregular edge and periphery is thin and prominently 



convoluted. Inner portion raised, dense, and marked with faint 



convolutions. Parallel striations are also very prominent at times. 



See Figure 21. Cells are very pleomorphic. 



