INCREASING FECUNDITY 
Remarkable Effect of Pituitary Substance on Poultry May Have Wide 
Application—Great Increase in Egg Production and Hatchability 
of Eggs Obtained 
ECUNDITY is one of the most 
Fk important factors in the practical 
application of genetics, whether 
it be in eugenics or animal- 
breeding. 
Any method of increasing the fecund- 
ity of valuable strains would be of great 
worth to the eugenist and the breeder. 
One such method seems to have been 
found by Lewis Neilson Clark, of 
Oldham Farm, Port Hope, Ontario, 
Canada, a member of this association 
who has been experimenting with the 
ductless glands of animals, by feeding 
extracts of them to chickens. By the 
use of an extract of the pituitary gland, 
he has increased the egg production of 
hens, sometimes nearly doubling it, and 
at the same time has secured an in- 
creased “‘hatchability”’ of the eggs. 
The pituitary gland of calves, secured 
by Mr. Clark from his local butcher, is 
a small rounded body attached to the 
under side of the brain, and consisting 
of two lobes, an anterior and a posterior. 
It is generally supposed to regulate, 
by its secretions, the nutrition of bone 
and other connective tissue, and to 
have many other far-reaching influences 
on the entire body. For the experiment 
here described, Mr. Clark used only the 
anterior lobe of the gland, which he 
ground up and mixed with sugar of milk 
to form a paste. This paste was 
dried at room temperature, ground to a 
powder, and weighed, the loss in 
weight amounting to 13.5 per cent. In 
the experiments recorded below 69 
milligrams of this powder, representing 
20 milligrams of fresh pituitary sub- 
stance (anterior lobe), were administered 
to each hen per day. 
RECORD OF HENS KNOWN 
“The first experiment attempted,” 
Mr. Clark writes,’ “dealt with thirty- 
five Single Comb White Leghorn hens 
hatched in April, 1913, mated, in two 
pens, to two cockerels of the same 
breed, hatched in May, 1914. These 
two pens were housed in two colony- 
houses, on free range, and had been 
used as breeding-pens for this season’s 
work before the dosing was commenced. 
I have, therefore, records of their egg 
production for several months previous, 
the laying being very steady and 
consistent. For the purpose of illus- 
trating the results of this experiment, 
it will be necessary to give only the 
egg production for a period of fourteen 
days prior to first dosing. It will be 
noted in Table I? that the production 
curve was declining, previous to dosing, 
this being only natural in view of the 
heavy and consistent laying of these 
hens since February. Both hens and 
cockerels were forcibly fed at night 
time with the powder, enclosed in 
gelatin capsules, the dose in each case 
being 69 milligrams. The first dose 
was given on the evening of May 20 and 
the last dose on the evening of May 28. 
A remarkable increase in production 
 -1The Effect of Pituitary Substance on the Egg Production of the Domestic Fowl. By Lewis 
Neilson Clark. 
2 The table is too long to be reprinted here. 
First dose evening of May 20. 
Journal of Biological Chemistry, Vol. XXII, No. 3, pp. 485-491; October, 1915. 
A summary is as follows: 
Last dose evening of May 28. 
Average daily egg production of experimental pens May 7 to May 14, inclusive, 19.25 eggs= 
55 per cent possible. 
Average production May 15 to May 23, inclusive (to 3 days after first dose), 16.11 eggs= 
46 per cent possible. 
Average production May 24 to May 30, inclusive (from 3 days after first dose to 2 days after 
last dose), 32 eggs=91.43 per cent possible. 
Average production May 31 to June 6, inclusive, 21.57 eggs=61.63 per cent possible. The 
pens were broken up on June 7. 
102 
