662 SUMMARY OF CURRENT RESEARCHES RELATING TO 



(2) The period of incubation. — Experimentally it is shown that the 

 greater part of this period is the expression of the time occupied in the 

 conveyance of the toxin from the periphery along the motor nerves to 

 the susceptible centres. 



(3) Tetanus dolorosus. — In all experiments with injection of tetanus 

 toxin into the substance of the spinal cord, there was observed as a first 

 symptom of intoxication a sensory disturbance, consisting in extreme 

 hyperesthesia, strictly localised, even when the muscular rigidity and 

 the exaggeration of the reflexes were becoming general. Experiments 

 made in this connection show that the tetanus toxin never reached the 

 spinal centres by way of the sensory nerves ; that the pain apparatus in 

 the spinal cord is so insulated from the motor that an intoxication of 

 the one group never goes over to the other ; and that the actual move- 

 ment of the toxin in the nervous system takes place, not in the 

 lymphatics but in the protoplasm of the nerves. 



(4) Theory of action of tetanus toxin.— The toxin is taken up from 

 the point of injection by the motor nerves, along which it passes to the 

 motor centres in the cord and excites there an over-irritability, resulting 

 in tetanic rigidity in the affected limb. The excess toxin then passes 

 in the fibres of the cord to the motor apparatus of the corresponding 

 limb of the opposite side. After a time the nearest connected sensory 

 apparatus of the reflex arc in the spinal cord is attacked. If the intoxi- 

 cation proceeds further, the motor tonus and the increased reflex irrita- 

 bility become general. The tetanus of warm-blooded animals consists 

 of two processes. One is primary, a motor intoxication : local muscular 

 rigidity ; the other, secondary, is a local sensory intoxication : a diffused 

 reflex tetanus, starting from the intoxicated neuron. 



(5) The behaviour of the tetanus anti-toxin in the organism. — It was 

 found that when tetanus toxin was introduced direct into a motor 

 nerve, anti-toxin was practically inert. It is concluded therefore that 

 anti-toxin does not reach the substance of the nerve-fibrils and centres, 

 and will therefore render harmless only the toxin in the blood and 

 lymphs, leaving that already in the nerve-substance untouched. 



Experiments with Bacterial Light. * — M. B. Issatchenko has 

 studied the light produced by the Photobacterium phosphorescens, and 

 has made experiments to determine the extent of its power in causing 

 the transformation in plants of protochlorophyll into chlorophyll. All 

 experiments were made in a perfectly dark room. The light was strong 

 enough for small objects to be distinguished, and for the study of its 

 spectrum which was from A = 0*46 to A = 0*55, the clearest part being 

 from A = 0*48 to A = 0*51. In colour the light was greenish. The 

 light from gelatin cultures attained its maximum in from 2-3 days. 

 The experiments were made by exposing to the light for periods varying 

 from 10 to 48 hours germinating seeds of clover, rye, and oats, and 

 afterwards treating the shoots with 95 p.c. alcohol and examining the 

 extract spectroscopically. An alcoholic extract was in all cases made 

 also before the experiment and examined in the same way. In none of 

 the latter was there evidence of chlorophyll, the band of protochloro- 



* Centralbl. Bakt, 2 ,e Abt., x. (1903) pp. 497-9. 



