186 VETERINARY SURGICAL THERAPEUTICS. 
Kitasato has succeeded in isolating it in pure cultures (1889). It 
is polymorphous ; sometimes it has the form of a regular rod (baton- 
net) with blunt ends, or of a delicate rod, short and sporulated 
(batonnet en battant de cloche), or of a spore. Under its bacillar 
form itis very vulnerable, succumbs in a few minutes to the action 
of a heat of 75°, or to the action of most antiseptics ; but the spores, 
which are constantly in tetanic matters, enjoy a great vital energy; 
they resist the action of antiseptics and require a temperature of 
105° and 115° to destroy them. , 
Vaillard and Vincent have observed that pure cultures of tetanic 
bacilli or spores act only by the toxines that they contain. Not only the 
microbe does not propagate in the tissues where it is deposited, but it 
disappears rapidly, and if, before it is inoculated, it is deprived of the 
toxine to which it is associated, the disease does not develop. It can- 
not produce its worst effects except when acting with some chemical 
substances or some ordinary microbes, especially the pyogenous. 
Inoculated alone, it is rapidly surrounded and destroyed by phagocytes ; 
in company with other micro-organisms, as it occurs with wounds in 
ordinary circumstances, these attract the phagocytes, absorb their 
activity and leave to the tetagenous elements all freedom to act. From 
the wound where it is elaborated, the tetanic toxine spreads and arrives 
in the blood vessels ; it fixes itself in the elements of the centers. The 
nervous cells contain in their protoplasm groups of elements possessing 
a special affinity for tetanic toxine, which they attract with great force; 
once the toxine is fixed on these elements, it rerhains on them fora 
long time and the lesions of the cells disappear but slowly. They take 
place as long as the wound remains infected, as long as the microbian 
pullulation lasts; ultimately, it penetrates either in small quantity 
(chronic tetanus) or in doses rapidly fatal (acute-tetanus). Thus are 
explained the persistency and increasing severity of the symptoms. 
The tetanic toxine gives rise to very different effects, according to 
the doses in which it is injected. On this, we have (1) doses that 
kill; (2) weaker doses, which give rise to more or less serious dis- 
turbances, but are not fatal; (3) still weaker doses, allowing immuniza- 
tion of animals without producing visible troubles. 
In 1891 Behring and Kitasato found that the liquids of animals 
made refractory to tetanus by the injection of toxine had obtained 
antitoxic properties. Those liquids (humours) contain an antitoxine 
which may inhibit, render harmless, an enormous proportion of tetanic 
poisons. The injection of a small quantity of serum renders animals 
refractory to tetanus insensible to the action of a large dose of toxine. 
It allows preventive and therapeutical interference. Kitasato having 
found that antitoxine subsists for some time in the organism of the 
horse, recommended already serum to treat the disease in that animal. 
