TRANSACTIONS OF SECTION I. 901 
4. On Protamines, the Simplest Proteids. By Professor A. Kosserr. 
5. Protamines and their Oleavage Products: their Physiological Effects. 
By Professor W. H. Tuompson. 
6. The Vascular Mechanism of the Testis. 
By Wauter E. Dixon, M.D., B.Sc. London. 
The method adopted was the Plethysmographic, both testes being rapidly 
shelled out, and, after incising or removing the tunica vaginalis, enclosing them 
in a gutta-percha oncometer. The animals used were mainly dogs and cats, 
although rabbits and goats were occasionally employed. By this method it was 
shown that the testis undergoes changes in volume passively as a result of altera- 
tions in blood pressure, and active changes due to vasomotor nerves. 
The following were the main conclusions which were drawn :— 
1. Operations involving the testis are usually followed by some vascular disturb- 
ance, the blood pressure falling and the heart beating more feebly. 
2, The sympathetic filaments in the spermatic cord may be divided into three 
groups according to the effect produced on the testis whilst stimulating their 
peripheral end, viz.: (a) vaso-constrictors ; () vaso-dilators ; (c) those producing 
no alteration in volume, these probably being afferent fibres associated with 
testicular sensation. 
3. The vaso-constrictor nerves to the testis were traced and shown to pass 
mainly through the anterior roots of the thirteenth dorsal and first and second 
lumbar nerves in the dog. There is still some doubt with regard to the position 
of the vaso-dilators. 
4, Injections of testicular extract produce a different effect in different animals ; 
in the cat there is a fall of blood-pressure with marked inhibition, whilst in the 
goat there is a considerable rise without the inhibition. The chief active con- 
stituent is nucleo-proteid. In every case the ultimate effect on the testis is one of 
dilatation. 
5. The substances having the most marked effect on testicular volume were the 
following :— 
(a) Gold Chloride—In small doses there is comparatively little effect on 
blood pressure. The testis first contracts and then gradually dilates, the dilated 
condition being considerable and permanent. 
(b) Cantharidin.—In very small doses (‘001 gramme to an animal of three or 
four kilos) there is first a rise in pressure with slowing, followed by a very insignifi- 
cant fall ; the intestinal area is dilated, and the testes and kidneys undergo marked 
constriction. This active testicular constriction is greater and more prolonged 
than that which could be produced with any other substance, and is followed by a 
stage of very considerable dilatation. 
(c) Valerian.—A concentrated infusion in medicinal doses produces ultimately 
a passive slight testicular dilatation. 
(d) Anhalonnine produces an entirely passive dilatation of testis as a result of 
rise in blood pressure. 
(e) Other substances.—The following substances all produced some testicular 
, generally insignificant: strychnine, cannabis indica, amyl nitrite, ergot, 
alcohol. 
