Blood Pressure in the Leech Hirudo Medicinalis

1. Intravascular pressure recordings in the lateral vessels of the leech, Hirudo medicinalis, show two distinct pressure patterns: high pressure phases (diastolic pressure: 5 ± 3 mmHg, systolic pressure: 48 ± 14mmHg) alternate with low pressure phases (diastolic pressure: 4 ± 2.5 mmHg, systolic pressure: 26 ± 11 mmHg). 2. The lateral vessel of one side produces high pressure pulses during peristaltic action while the other vessel generates low pressure pulses during non-peristaltic action. After 20–60 pulses a transition occurs, which sometimes appears more gradually.

A simple method for oral administration of drugs in solid form to fully conscious rats

The design and application of a simple capsule administration tube for miniature capsules are described. Experiments with rats have shown that the tube is capable of depositing capsules at the distal end of the oesophagus. Regardless of the location of the capsule in the oesophagus, provided normal peristaltic action occurs, the capsule will have reached the stomach and discharged its contents within 10 min. After a short training period of 3-4 days the insertion of the tube does not appear to cause the rats undue discomfort, nor does it cause tissue damage. The procedure, which can be performed rapidly by 1 technician, is ideally suited for dispensing solid materials to fully conscious animals.

IV. On peristaltic induction of electric currents

Recent observations on the propagation of electricity through wires in subaqueous and subterranean telegraphic cables have brought to light phenomena of induced electric currents, which, while they are essentially different from the phenomena of what has hitherto been called electro-dynamic induction, are exactly such as might have been anticipated from the well-established theory of electrical equilibrium, had experiment afforded the data of relation between electrostatical and electro-dynamic units wanted for determining what dimensions of wire would be required to render these phenomena sensible to ordinary observation. They present a very perfect analogy with the mutual influences of a number of elastic tubes bound together laterally throughout their lengths, and surrounded and filled with a liquid which is forced through one or more of them, while the others are left with their ends open ( uninsulated ), or stopped ( insulated ), or subjected to any other particular conditions. The hydrostatic pressure applied to force the liquid through any of the tubes will cause them to swell and to press against the others, which will thus, by peristaltic action, compel the liquid contained in them to move, in different parts of them, in one direction or the other.