558 TRANSACTIONS OF SECTION I. 
this is the case no apneeic pause is to be observed. The probable reason for this 
departure from the normal is that, although the ventilation has produced a 
removal of carbonic acid from the blood, the fall in hydrogen-ion concentration 
is prevented by a formation of acid products of incomplete combustion. 
3. The Action of the Venom of some Australian Snakes on the 
Corpuscles of some Bloods. By Professor D. A. Wsusu, M.D., 
and Dr. H. G. CHAPMAN. 
4. A Comparison of the Activity of Hatracls of the Pars Intermedia 
and Pars Nervosa of the Ox Pituitary. By Professor P. T. 
Herrine, M.D., f.R.C.P.H. 
It is possible to remove from the posterior lobe of the fresh ox pituitary with 
the aid of a fine pair of curved scissors small quantities of the epithelium of the pars 
intermedia. The material thus obtained from a number of pituitaries was dried, 
powdered in a mortar, and made up by boiling in Ringer’s solution into extracts of 
definite percentages of the dried epithelium. Pars nervosa was similarly isolated 
and prepared. 
The extracts were tested upon the virgin rat’s uterus, the method employed being 
a modification of Kehrer’s and Dale’s procedures. The extracts were also tested 
upon the mammary secretion of lactating rats, and upon the blood-pressure, kidney 
volume, and secretion of urine in cats. 
The extracts of both pars intermedia and pars nervosa exercise a powerful stimu- 
lating effect upon the uterus and the secretion of milk, but the pars nervosa gives 
the stronger action in each case. By a comparison of the action of different strengths 
of extracts it is found that the pars nervosa is from two to five times as powerful in its 
effects as pars intermedia. Very minute doses are active ; immersion of the uterus 
for 15 sec. in ‘0005 per cent. of the dried pars nervosa results in a well-marked con- 
traction. The skate pituitary, in which there is no pars nervosa, also yields a material 
which acts on the uterus and mammary secretion in a similar manner. The pure 
pars glandularis of the anterior lobe of the ox pituitary has no such action. It is 
probable, therefore, that the active material has its origin in the epithelial cells of 
the pars intermedia. Many of these cells invade the pars nervosa, undergoing an 
alteration there into hyaline bodies, which are very numerous in the pars nervosa 
of the ox pituitary. 
Extracts of the pars intermedia show no specific action upon the blood-pressure, 
kidney volume, and urinary secretion of cats, even in doses of a ‘5 per cent. extract 
of the dried epithelium. Extracts of skate’s pituitary are similarly inactive. Ex- 
tracts of the pars nervosa on the other hand give marked effects even in very minute 
doses. The injection into the jugular vein of 2 c.c. of a ‘01 per cent. extract of dried 
pars nervosa gives a typical prolonged rise of blood-pressure, great dilatation of the 
kidney, and increase of the secretion of urine. A similar dose of a *001 per tents 
extract shows a slight action of the same nature. 
The evidence points to there being at least two separate active principles in the © 
posterior lobe of the pituitary body. The one, derived from the pars intermedia, 
acts upon the uterus and mammary gland, the other, found only in the pars nervosa, 
brings about the rise of blood-pressure, and acts specifically upon the kidney dilating 
its blood-vessels, and causing increased secretion of urine. 
The principle which acts specifically on the kidney may be derived from the 
ependyma cells of the pars nervosa, but this is unlikely. Extracts of no other part 
of the central nervous system, e.g., the filum terminale of the spinal cord, have any 
such action. Jt is more likely that the material is derived in some manner from a 
further breaking down of the hyaline bodies, and has, therefore, its ultimate source 
also from the epithelial cells of the pars intermedia. 
The expenses of this research have been borne by a grant from the Carnegie Trust. 
5. The Influence of the Thyroid upon the Activity of the Suprarenals 
and Pituitary Body. By . Professor P. T. Herrina, M.D., 
1s cad OR ee 
