M. ANANTARAMAN                                   129

No. 13 also infected likewise previous to 23 October 1940 continues to dis-
charge eggs to this day, 9 June 1941.

In artificial infections, the same technique as was employed for 0.
columbianum was adopted here. Both gradual and sudden infections were
caused and the calf that took superimposed doses of larvæ died sooner than the
one which had an intake of larvæ in one instalment.

Death of the host may be due to two varieties of œsophagostomiasis,
(1) traumatic and (2) toxic.

In calf No. 4. which had had repeated doses of larvæ from 16 October
1939 to 27 December 1939 in 23 instalments each ranging from 100 to
1200 in number, death was caused during the larval development of the
worm. The motion was loose and sloppy on 28 December 1939 and 29
December 1939 ; the animal went off feed from 18 January 1940, showed an
inordinate thirst on the 21 and 22, and started a mucus and blood-tinged
diarrhoea from the 18, which persisted till death and with which numerous
ourth-stage and adult 0. radiatum were passed. The attitude was dull and
indifferent, the abdomen tucked up, and the body was trembling, for two days
prior to its death on the 22 January 1940. There was a general physical
decay in the last stages. Numerous worms, adult and larval, were present
in the intestine.

(2) Calf No. 2 was drenched with 1500 larvæ on 12 September 1939.
Symptoms definitely attributable to this infection were not observed until
several months had passed. During the last days, constipation and diarrhoea
alternated in a mild form, and the animal had been much weakened. Its
Weight on 19 September 1939 was 112 lb., which gradually increased to 132
lb., on 18 January 1940 and thereafter declined to 116 lb. on 9 May 1940.
There was a good appetite. The debility was enormous in the last stages and
the animal was unable to stand steady due to muscular weakness of the hind-
limbs, and frequently fell on the floor in attempting to rise. The last fall on
12 May 1940 resulted in abrasions over the body and probably a sprained
back. The animal proved unequal to the strain and expired during the night
of 14 May 1940. About 40 worms were present inside. Here death may be
ascribed to verminous intoxication.

                             GENERAL CONSIDERATIONS

The development of O. radiatum proceeds on the same lines as Bunostomum,
Haemonchus and other species of Oesophagostomum, being in five larval stages
and with an ecdysis between two successive stages. The following table
represents in a summarised form the order and place of their occurrence.

*Eggs of O. radiatum are discovered in the faeces of the calf even on 31 March 1942,
So, the infection may be regarded as lasting for at least 17 months.