128 A NEW BACILLUS PATHOGENIC TO FISH, 



highly refractile spore slowly enlarged, and at the same time 

 became less and less refractile. The rod emerged from one of the 

 poles and grew outwards until the protruded end was as long as 

 the spore case. By this time the distinction between rod and 

 spore had practically disappeared. A protrusion then appeared at 

 the other end of the spore case, and growth proceeded in two 

 directions. The spore case was then thrown off, and this was 

 followed by a division of the lengthened rod into two parts. 

 The daughter bacillus, formed from the end last to emerge, slowly 

 bent round until it was at an angle of 45° with the other rod, 

 when it suddenly slipped along the side of the latter. Germina- 

 tion occurred in 3^ hours at laboratory temperature (20°); an 

 hour later there were two cells and in another, four bacilli. The 

 dimensions of the mature rod after division and whilst thus 

 imbedded in gelatine were 1 -5 : 7 '5 /x. 



The early gelatine cultures. — The characteristics that have been 

 described appear to be permanent, for the characters of the 

 twelfth transfer or crop were identical with the third. The first 

 and second crops in gelatine differed markedly from the later. 

 The gelatine stab infected from the first agar plate produced an 

 arborescent growth along the needle track — an appearance similar 

 to that of anthrax. Cultures from this, however, failed to repro- 

 duce a similar appearance. There developed instead the uncharac- 

 teristic filiform growth. The early colonies in gelatine plate 

 culture grew as white points from which there radiated straight 

 processes about 0-5 cm. long, and these gave the colony the 

 appearance of a tuft of delicate crystalline needles. When 

 magnified 60-fold the older rays were seen to be corkscrew-like, 

 the younger ones straight. By the third transfer the rayed 

 appearance had changed to the zonal, which has been described. 



Affinities. 



The organism has many points in common with Bac. subtilis, 

 the common hay bacillus, but differs from it in the folded appear- 

 ance in agar culture and the rosette-like folded processes of the 

 young surface colonies in gelatine plate culture. Other differences 



