1. The anatomy of the termination of the thoracic duct in
rabbits is described.
|| 2. At operation, the thoracic duct was exposed and divided;
and uncontaminated lymph obtained.
|| 3. The anti - mitotic alkaloid, colchicine, given intravenously
in doses of 2.5mg. /kg. body weight, was found to increase the
output of both large and small lymphocytes 2 to 3 hours after
the injection, usually without affecting the rate of flow.
That there was no significant decrease in the output of
thoracic duct lymphocytes for 10 hours following colchicine
suggests that the majority of thoracic duct lymphocytes are not formed in the preceding few hours. This suggestion
is in agreement with the observation that only up to 2.5%
of the cells of the thoracic duct were in arrested mitosis
following colchicine. Mitoses were never observed in small
lymphocytes. It is thought that large lymphocytes are capable
of division while small lymphocytes are not. Nuclear
abnormalities, karyolysis and pyknosis, were seen in all types
of lymphocytes and these abnormal forms were also present
in the blood. Cells having mitotic figures were however
not seen in the blood; some evidence is presented that
these were trapped in the pulmonary circulation.
|| 4. A profound granulocytopaenia occurred in the first
hour following colchicine injection. In unanaesthetised
animals this was followed by a granulocytosis. In anaesthetised
or anaesthetised and operated rabbits, the granulocytopaenia
persisted, though anaesthesia or operation by themselves were
found to produce a granulocytosis. The cause of this altered
reaction remains obscure.
|| 5. Colchicine, anaesthesia and operation all produced a fall
in the level in the blood lymphocyte.
|| 6. Occasional normoblasts were found in the peripheral blood
|| 7. The spleens of rabbits receiving colchicine were smaller
|| 8. The number and morphology of small and large lymphocytes
of the thoracic duct in rabbits immunised against S. typhi
did not appear to differ from the normal. The morphology
of the thoracic duct lymphocytes after colchicine was the
same as in unimmunised rabbits.
|| 9. Preliminary observations suggest that the number of large
lymphocytes in the peripheral blood of immunised rabbits is
|| 10. Antibody titres of thoracic duct lymph plasma were
consistently lower than those of blood serum and of thoracic
duct lymphocytes, estimated after homogenization. Colchicine
administration did not alter these titres.
|| 11. Thoracic duct lymphocytes were taken from immunised
rabbits and injected, unhated, into normal rabbits.
Antibody appeared in the recipient, and the titre rose during
the next few days. The titre began to fall at about the 9th
day. Control transfers of cells taken similarity but heated
to 56 °C for 30 minutes produced in most rabbits only a transient
titre in the recipient, the antibody level in these rabbits was,
after the first day, always significantly lower than that in
rabbits receiving unheated cells. It is thought that the
transferred, unheated cells, or their progeny, continued to
produce antibody until the homograft reaction destroyed them.