TRANSACTIONS OF SECTION I. 643 
to their insolubility in aqueous media, the nitric esters of the acids owing 
apparently to what we may term the inhibiting influence of the carboxyl group. 
In the case of some of the ethyl esters of the last-named compounds a fall of 
blood-pressure commences some minutes after an intravenous injection, the cause 
of which has not yet been ascertained. 
The first group—the nitric esters of monhydric aleohols—are relatively weak 
vaso-dilators. Methyl nitrate, for example, injected intravenously, is more 
than ten times weaker than glycerol trinitrate, and when administered by the 
stomach to man, is more than a hundred times weaker. They can be given in 
sufficiently large doses to rabbits to produce unconsciousness without causing 
death. 
The vaso-dilating action of the remaining group—the nitric esters of the 
polyhydric alcohols and sugars—considering their solubility, is powerful. The 
differences exhibited by the various substances are mainly quantitative and are 
largely due to the differences in solubility of the substances in aqueous media. 
The presence of hydroxyl groups, however, diminishes the action of a substance 
as compared with the fully nitrated compound very considerably. 
The action of the nitric esters seems to be associated with their suscepti- 
bility to reduction and conversion into nitrites under the influence of caustic 
alkalies, and it is not improbable that a similar reduction occurs in the muscle- 
cells themselves. 
15. On Coriamyrtin and Tutin. By C. R. Marswat. 
Coriamyrtin is the active glucosidal principle in Coriaria myrtifolia (L.), an 
ornamental shrub indigenous to many countries bordering the Mediterranean. 
Tutin is a similar principle, present in the New Zealand species of Coriaria— 
viz., O. ruscifolia (L.), C. thymifolia (Humb. and Bonp.), and C. angustissima 
(Hook.). Both are colourless crystalline substances, but they differ in chemical 
composition and in physical characters. 
Both substances produce similar pharmacological effects, but coriamyrtin is 
more powerful, more rapid, and more transient in its action than tutin. When 
injected subcutaneously into rabbits they produce a marked increase in the fre- 
enency of the respirations and a slowing of the pulse-rate, often salivation, 
followed, if the dose is sufficiently large, by convulsions. After large doses 
the earlier convulsions are partly tetanic in character, the later ones are usually 
wholly clonic. After small convulsive doses the whole of the convulsions are 
generally clonic in character. They commence in the head, and extend, if they 
do extend, posteriorly. The Jacksonian character of these convulsions is better 
seen after tutin than after coriamyrtin. Both substances produce a fairly con- 
stant type of ‘forced movements.’ They occur most typically as end-reactions 
after large convulsive but non-toxic doses of tutin. A fall of body temperature 
is produced both by convulsive and non-convulsive doses of the two substances. 
The resniratory and cardise effects are due to stimulation of the medullary 
centres. There is also stimulation of the vasomotor centre. The convulsions 
are due to increased excitability of all parts of the central nervous system. 
The cortical motor-centres are most susceptible, but clonic convulsions are 
obtained after excision of the cerebral hemisvheres, and tonic-clonic movements 
may be obtained in the hind limbs of cats after the division of the spinal cord 
in the lower dorsal region. This increased excitability of the spinal cord is 
more easily obtained with coriamyrtin than with tutin. 
Anesthetics, and especially chloroform, greatly diminish and may annul the 
stimulant action of these substances on the medullary centres. The respiratory 
centre seems most susceptible to this change. Instead of a large increase in the 
frequency of the respirations there is, with full anesthesia, a diminution, with 
deeper and more prolonged inspiration. This effect. appears relatively late. and 
is usually accompanied or quickly followed by slight twitches of the limbs. 
It is, therefore, probably to be ascribed to an increase in tone of the respiratory 
muscles rather than to a specific action on the respiratory centre. 
In frogs these substances produce increase in the frequency of the respiration, 
the appearance of muscular stiffness, with slnggishness of movement and inco- 
ordination, so that the animal assumes bizarre positions and sinks on the table, 
and later convulsions, mainly tonic in form. The main difference between the 
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