INDEPENDENT MOTION OF THE LEUCOCYTES 413 



II. Substances retarding the heart's action. 



a. An induction current of electricity, h. Aconitine, acting energetically. 



acting energetically. i. Potassium nitrate, acting energeti- 



b. Ammonia, acting energetically. cally. 



c. Ethyl ether, acting energetically. g. Ethyl alcohol. 



d. Oxalic acid, acting energetically. h. Chloroform. 



e. Carbolic acid, acting energetically. i. Carbonic oxide. 

 /. Veratrine, acting energetically. j. Carbonic acid. 



g. Atropine, acting energetically. k. Sulphuretted hydrogen. 



III. Substances whose action is indifferent. 



1. Muscarine. 2. Curare. 3. Atropine, acting slowly. 4. Strychnine. 



The above-named substances comprise those which in the vertebrates effect 

 a change in the activity of the motor nerve-ganglia of the heart and the muscu- 

 lar fibres. Hence it follows that the heart of the larval Corethra consists of 

 muscular fibres provided with ganglia, and that the contractions of the muscu- 

 lar fibres are provoked through the agency of the ganglia. But since muscarine, 

 atropine, and curare, whose influence in stopping the heart's action of verte- 

 brates is known, in insects either have no action or only make the pulsations 

 slower; it seems to follow that the heart of the larval Corethra possesses no 

 similar apparatus for lessening the heart's action, and this is also confirmed by 

 anatomical studies. On the contrary, aconite acts, as we must from observations 

 conclude, exclusively on the motor centres and the muscles, but not on the ap- 

 paratus for lessening the heart's action, which, as has been remarked, is not 

 present in the larval Corethra. (Kolbe ex Dogiel.) 



Dewitz has discovered an onward movement of the blood corpuscles, some- 

 what independent of the general circulation. This independent motion of the 

 blood corpuscles is not only a creeping one like the amoeboid motion of the white 

 corpuscles of vertebrates, but they have besides a peculiar swimming movement. 

 Dewitz noticed this in the hind wings of a recently emerged meal-worm beetle 

 ( Tenelmo molitor), still white and soft, after they had been cut off. The tissues 

 forming the matrix within the wings constitute a network filled with blood. 

 The current of blood within the wing thus cut off may be stopped flowing by a 

 tap on the firmly clamped object-bearer on which the wing is placed, or by 

 drawing it by an apparatus described by the same author, to incite in one way 

 or another the blood corpuscles to swim forwards. When a corpuscle is disposed 

 to move, we see it first stirring restlessly, or wabbling about, in this way chang- 

 ing its form ; then it moves forwards, and does not come to a standstill. If it 

 remains still there, after a while, by tapping, it begins again its movements. 



"Should one yet doubt the fact of this spontaneous movement of the blood 

 corpuscles, he will surely be convinced of its correctness by observing the so-to- 

 speak reluctantly springing motion of a blood corpuscle in the wing of Tenebrin 

 molitor witli the simultaneous change of appearance and shape of the corpuscle." 



This spontaneous or independent motion of the blood corpuscles is also pro- 

 duced by the heating apparatus. As soon as the corpuscles lie still in the 

 severed wing and they are warmed, the corpuscles begin to pass through the 

 meshes of the tissue. When cooled, the motion ceases, but as soon as the tem- 

 perature rises to a certain grade, the corpuscles again move onwards. 



To explain this independent motion Dewitz thinks that they take up and then 

 expel the blood-fluid, and in this way cause their motion. This independent 

 motion is necessitated, in order that the stream of blood may become so regu- 



