BACILLUS TETANI 513 
to the bottom of the vessel, and development is at an end. Spores are 
found in abundance is the sedimented culture. 
Growth in milk is feeble, and there is no obvious change in the appear- 
ance of the medium. Coagulated serum is unaltered in appearance, 
but development proceeds with moderate luxuriance. Meat medium 
is unaltered in appearance, and there is no suggestion of liquefaction 
or other proteolytic change. Gelatin may be very slowly liquefied. 
Ammonia is produced only in small quantities, apj)roximating that 
characteristic of B. diphtheria^. Indol, mercaptan and hydrogen sul- 
phide are formed in appreciable amounts. The organism in pure cul- 
ture is toxicogenic, but only slightly proteolytic.^ 
Products of Growth. — Gelatin, coagulated blood serum, meat medium, 
coagulated egg and casein, furnish suitable nitrogenous nutriment for 
B. tetani, but the organism fails to induce noteworthy or deep-seated 
chemical changes in these media. The older observations attributed 
marked proteolytic powers to the organism, however. Improve- 
ments in methods of obtaining pure cidtures have been followed by the 
isolation of tetanus strains which are less and less proteolytic. Thus, 
Tissier and Martelly^ found that their cultin-es of tetanus bacilli were 
less proteolytic than those previously recorded. They concluded that 
the tetanus bacillus secreted little or no soluble proteolytic enzyme, 
which would act upon albuminous substances. Still later studies have 
shown that B. tetani is culturally relatively inert in so far as deep seated 
chemical changes upon protein are concerned. In like manner, the 
older observations that B. tetani formed large amounts of gas incidental 
to its growth have been shown to be fallacious. Achalme-^ stated that 
B. tetani has no apparent action upon hexoses— glucose or galactose; 
bioses— maltose, lactose and saccharose; hexose alcohols — sorbitol 
mannitol and dulcitol; nor upon other carbohydrates. It appears to 
be true, however, that some acid is produced in all protein media 
incidental to the development of the organism. 
Toxin.— The most characteristic and striking metabolic product 
formed by B. tetani is an extremely potent, soluble or extracellular 
toxin. Ehrlich^ has shown that this toxin consists of at least two 
components, which may occur in variable proportions in different 
cultures. These components are recognizable only by the physiological 
reactions they induce when injected into suitable experimental animals. 
One of these, a neurotoxin, has been designated Tetanospasmin; this 
is relatively thermolabile and incites the distinctive toxic contractions 
or spasms which are characteristic of the disease tetanus. The other 
component, Tetanolij.nu,^ is relatively thermostabile, and dissolves red 
bloofl cells. It is doubtful if the tetanolysin is of great significance in 
the clinical manifestations of tetanus. 
' This is not in accord with published descriptions. A careful study of cultures of 
unquestioned purity has shown that strong to.xin-producing strains do not exhibit the 
evidences of proteolysis ordinarily ascribed to them. 
= Ann. Inst. Pasteur, 1902, 16. 865. ' Ibid., 1902, 16, 633. 
' Berl. klin. Wchnschr., 1898, 35, 273. ' Madsen: Ztschr. f. Hyg., 1899, 32, 214. 
33 
