CONTRIBUTIONS TO THE CYTOLOGY OF THE BACTERIA. 458 



generally to be found in my preparations, but usually in small 

 numbers. 



Good preparations can be obtained by the osmic acid or 

 formalin method with Giemsa staining (see p. 415), and Heid- 

 enhain's iron-hasmatoxylin — when sharp differentiation has 

 been achieved — gives very good pictures of the structure of 

 these organisms. 



In PI. 18, figs. 113 and 114, will be seen some fusiform 

 organisms from a moist fihn preparation of the contents of 

 the large intestine of L. mural is, fixed with sublimate- 

 alcohol and stained with Heidenhain. It will be seen that 

 each cell contains a single, darkly staining, centrally situated, 

 spherical mass, which I believe to be the nucleus. I have 

 not obtained any satisfactory preparations which show a divi- 

 sion of this body in this particular form, but from analogy 

 with similar organisms, I have little doubt that it divides in 

 the course of cell division. 



Small single individuals (fig. 114) have the characteristic 

 spindle shape, and measure 4 /i —4"5 /^ in length. The ends 

 are sharply pointed. No other structures besides the nucleus 

 were visible in the cells. 



In this form — as in all the other fusiform organisms which 

 I have investigated — double individuals are very common 

 (fig. llo) . They arise from dividing single individuals through 

 an incomplete separation of the daughter-cells — in the same 

 way that D i p 1 o c o c c u s form s are produced by Micrococci. 



Smaller forms than those just described also occur in the 

 lizard. They all show a similar structure. Fig. 68, PI. 17 

 is of a small double form, stained with Giemsa's stain. Each 

 individual shows a distinct nucleus, as in the Heidenhain- 

 stained individuals. The length of this double organism was 

 approximately 5^^. 



(b) "Fusiform Bacteria " from Frogs and Toads. 



The common English frog and toad (R. temper aria and 

 B. vulgaris) occasionally contain fusiform organisms in 



