A. A. MERLIN ON BACILLI OF BUBONIC PLAGUE. 389 



endoplasm. The protuberant knob or boss is a common feature 

 in many such micrococci, and when present appears to be in- 

 variably situated on the Hne of one of the internal divisional 

 partitions ; the flagellum also, when observable, having its point of 

 attachment so placed. The protuberances may therefore be partly 

 due to the contracted or coiled-up flagella. 



Almost all micrococci of the plague and other species examined, 

 such as those of pneumonia, swine fever, gonococci, etc., exhibit 

 the characteristic quadripartition of their contents ; but as many 

 individual examples are considerably under the 40^00 ^^^ of ^.n 

 inch in diameter, the details of their internal structure are in 

 such instances beyond the range of our present optical means, 

 although traces of the divisional partitions may be detected in 

 smaller forms than might be expected. 



Fig. 8 represents a double gonococcus, about the xeioo"^^ ^^ ^^^ 

 inch in longitudinal diameter, showing a quadripartite arrange- 

 ment of both cell contents. 



It is believed that most of the bacteria with figure-of-8 or 

 micrococcus forms will be found to possess a structural disposition 

 of their endoplasm analogous to some one of the above examples. 

 Micrococci in zoogloea exhibit a similar appearance to that shown 

 in fig. 4. 



Of the rod-like and filamentous varieties the B. anthracis will 

 prove interesting. Fig. 9 represents a segment from a long 

 filament of this microbe in process of spore formation. The 

 endoplasm is here arranged in a tetragonal form on either side 

 of the translucent and highly refractive spore, each tetragon 

 having its contents divided into four equal parts as figured. 

 The spore is in this instance not fully grown, mature spores being 

 usually more elongated. Yery large spores occupy much of the 

 available space in the segments, thus crowding and greatly 

 compressing the adjacent endoplasm. 



Fig. 10 shows the structure of two sporeless segments from 

 another filament on the same slide. The partitioned squares of 

 endoplasm are in this case arranged in pairs. From the study 

 of other specimens it would seem that the spore is found between 

 such contiguous squares, gradually pushing them apart in the 

 progress of its growth until each segment resembles Fig. 9. 



Fig. 11 is of a long segment, the contents of which are 

 somewhat curiously disordered. An irregular disposition of the 



