PRODUCED BY ATROPIA IN COLD-BLOODED ANIMALS. 451 



series of clonic spasms. During the first attacks of tetanus the posterior ex- 

 tremities are often more or less abducted, and immediately after each attack 

 they become flaccid ; but the anterior extremities almost always remain rigidly 

 flexed. At a somewhat later period tetanus of a still more violent character, 

 and of longer duration, may be excited, and the attacks are now almost in- 

 variably emprosthotonic. During them, the posterior extremities are rigidly 

 extended ; while at their conclusion, not only do the anterior extremities remain 

 flexed, but the head continues bent downwards by tonic spasm of the muscles of 

 the abdomen, chest, and neck. 



A series of such attacks may be produced by repeated touches of the skin ; but 

 when a number are excited in quick succession, the convulsions become shorter, 

 and rather less violent, though they reacquire all their former violence after a 

 period of rest. 



During the convulsive stage, and especially at its latter portion, the animal 

 may execute various movements ; but from the difficulty with which these are 

 performed, even when they do not themselves excite spasms and convulsions, it 

 is apparent that the power of voluntary movement is still considerably impaired. 



The period during which this tetanic condition remains was found to vary 

 greatly in different experiments ; and, as might have been anticipated, the larger, 

 within certain limits, the dose of atropia administered, the longer the continuance 

 of this condition It has been observed to continue in some experiments for only 

 a few hours ; in others, for several days ; and, in one experiment, for even so 

 long as seventeen days. 



This great protraction of the stage of tetanus occurred in an experiment in 

 which a small fatal dose of the sulphate was administered, and this experiment 

 will now be described, as it admirably illustrates the usual sequence of the 

 phenomena. 



Experiment XIX* — A solution of Q-45 grain of sulphate of atropia, in eight 

 minims of distilled water, was injected, by means of a Wood's hypodermic 

 syringe, f into the abdominal cavity of a healthy male frog, weighing 455 grains. 

 For some minutes afterwards, the frog jumped abotit very actively; but in about 

 eight minutes its movements were slow and sluggish, and some weakness 

 occurred in the anterior extremities, and in ten minutes it was unable to jump 

 with normal activity, and when undisturbed lay quietly on the abdomen and 

 chest. A few minutes later, the respiratory movements of the abdominal and 

 chest muscles ceased, those of the throat muscles, however, continuing, and the 

 head rested on the lower jaw. In twenty-one minutes, the frog was placed on the 

 back, and it then made some feeble voluntary movements of the limbs, which 



* The numbers of the expei-iments of which detailed descriptions are given in this section have 

 reference to the arrangement in Table I. at the end of the section. 



•j- This instrument was employed in all the experiments in this investigation. 



