No; 424.].. THE BLOOD FLOW: IN LUMBRICUS. 321 
regarding the coutse-of the flow have been. made out by this 
means, although the injection gives.a good demonstration of 
the-anatomy of the Hpasiiatu fuo qus 
DESCRIPTION oF x2 whe? 
Many experiments. give no definite results,- owing to thd 
condition of the worm or to violent disturbance of the circula- 
tion. Great care is required in recognizing and interpreting 
the results, especially in observing pulsations. It has been 
found that when fairly clear and definite results are obtained, 
the same result is given by the different methods. 
I. The Dorsal Vessel. —'The fact that the blood flows for- 
ward in the dorsal vessel up to the hearts is clearly shown by 
the course of the pulsations, In front of the hearts the pulsa- 
tions are not conspicuous, and special attention was given to 
determining the course of flow. in this part of the dorsal. 
Among the many worms dissected afew- were found in which 
the pulsations of the dorsal were distinctly seen running for- 
ward to the pharynx. The dorsal vessel. was clamped in front 
of the hearts in.a number of worms, and in all cases the blood 
collected behind the clamp and disappeared in front of it. The 
blood flows forward throughout the whole length of the dorsal. 
2. The Ventral Vessel. — The experiments noted below 
and the general agreement of authors make it. certain that 
the blood- flows backward in the ventral vessel back of the 
hearts. The course of the flow. in front of the hearts was 
shown by clamping the ventral vessel in the seventh somite. 
In every case the blood collected behind the clamp and disap- 
peared in front of it, indicating a forward flow. 
3. The Subneural and Lateral Neurals. — The best results 
are obtained. on these vessels by opening the worms from the 
ventral side. When the subneural.vessel was cut the blood 
flowed only- from the anterior cut end, Ze, backward. The 
same result was obtained constantly. by pinching the subneural 
with forceps: the blod collated: aen distinctly in front of the 
forceps and di ^ These ——_ were 
tried in all regions. of the worm. 1s 

