1912.] On the Systematic Position of the Spirochcets. 189 



of Treponema which I have studied. (A chambered structure cannot be 

 demonstrated with certainty in the small species of Treponema and 

 Spirochceta.)* 



(8) In Gristispira there is a peculiar axial thickening of the pellicle — the 

 crista. I regard this as the homologue of the axial fibre of Spirochceta 

 plicatilis. No similar structure exists in Saprospira and the largest forms of 

 Treponema. (In the smallest species of Spirochceta and Treponema, it is not 

 possible to determine whether any structure of this sort is present or not.) 



(9) Metachromatic granules (" volutin " granules) are present in Cristispira, 

 Saprospira, and Spirochetal Possibly they occur in Treponema also, but I 

 have not succeeded in demonstrating their presence or absence in these 

 forms on account of their very small size. 



(10) Colouring matter (chromophyll) is absent. % 



(11) Cyanophycin granules are absent.§ 



(12) The method of multiplication is always by transverse division — 

 division being simple in Gristispira and Treponema, multiple in Saprospira 

 and Spirochceta. 



(13) Correlated with this method of multiplication there is a marked 

 peculiarity in the variation of the dimensions of the body, in all four 

 genera of the Spirochaets. The individuals of any species show a considerable 

 variability in length — due to growth in one dimension of space — but not in 

 breadth. 



I may add that I have obtained no evidence of spore-formation or sexual 

 processes in any Spirochaet, and I regard as inconclusive all the evidence 

 adduced by others to prove the existence of these phenomena. 



If the Spirochaets be compared, in respect of the characters enumerated 

 above, with the Plagellata, it will be found that the only common characters 

 are those numbered 2, 4, 9, 10, 11. But it will also be found that these 

 characters are common to a very large number of Protista. The differences, 

 on the other hand, are — in my opinion — so pronounced as to exclude the 

 Spirochaets not merely from the Flagellata, but from the whole group of the 

 Protozoa. The combination of characters numbered 1, 3, 5, 7, 8, 13 does not 

 occur in any known protozoon. 



* From Zulzer's just published account of the large Spirochceta plicatilis — a form which 

 I have not studied in detail — it appears that this organism also possesses protoplasm 

 with a chambered structure. 



t They have been demonstrated in Spirochceta plicatilis by Ziilzer. I have not 

 succeeded in demonstrating them in the two much smaller species which I have studied. 



\ This is present in all Cyanophycese. 



§ They are present in all Cyanophycese except Spirulina — so far as I have been able to 

 determine. 



