FORMS OF GROWTH. 



33 



Fig. 3. According to a remark of Emmerich's, these arcuate forms 

 of growth are more especially abundant in muciferous substances, 

 e.g. in the excrement of snails, which is rich in mucin, as also 

 among the algas (already in a state of decomposition, and therefore 

 abounding in vegetable mucus) frequently covering the sides of 

 drains and watercourses. 



E. WEIBEL (I.) has published a series of observations on these 

 forms of growth, while fuller information concerning the spirilla 

 frequently to be found in the drainings from manure heaps can be 

 obtained from KUTSCHER'S (I.) treatise on this subject. 



FIG. 3. Spirocheeta and Spirilla. Mag. 950. (After P. Baumgarten.) 



1. Spirochsete Obermeieri, the cause of relapsing fever (Febris recurrens). 



2. Spirochseta from human dental mucus. 



3. Denecke's Spirochsete from putrescent cheese. 



4. Spirochsetal form of Koch's Cholera asiatica bacillus. 



5. Spirillum volutans, Conn. 



When the longitudinal development is excessive, then the 

 name of thread bacteria is given to the cells, which are further 

 distinguishable into the forms to be noticed later Cladothrix, 

 Streptothrix, Crenothrix, and Leptothrix being described in Chapter 

 xxxiv., and Beggiatoa and Thiotlirix in Chapter xxxv. More 

 detailed notices of the Diplococcus, Streptococcus, Pediococcus, 

 Staphylococcus, and Sarcina forms of growth will be found in 

 Chapter iv. 



28. Dimensions of Bacteria. 



Notwithstanding our previous statement that the bacteria are 

 the smallest of all known living organisms, it can be established 

 that the differences (Fig. 4) in their size hitherto observed must 

 be characterised as very considerable. In the smallest kinds the 

 dimensions are under i n, i.e. are less than o.ooi m.m. For 

 instance, the diameter of a lactic-acid-producing Coccus examined 



VOL. I. C 



