260 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [III, III.

tion would have been higher even than in the crossbreds, whilst in purebred Indian
cattle the condition might have been rare. Such a result, of course, would indicate
the possibility of a dietary deficiency due to innate lack of metabolic adaptation
in the imported cattle.

As that character of the animal known as " constitution " rests no doubt on a
multiple factor basis, it is obvious that the crossbred cattle would not inherit either
of the parents' " constitutions " in a clear-cut Mendelian manner. The metabolic
adaptation of the crossbreds would be more or less deficient and this would be more
pronounced, from the genetical multiple factor point of view, in the cross genera-
tion, quite apart from the fact that in addition these individuals would be three-
quarters European blood. From your records I see that many of the defective
calves are such three-quarter breds. You will see, however, that the actual condi-
tion does not appear to be directly due to a genetical factor, but to an indirect
constitutional factor which allows the development of such a condition in the
presence of some dietary deficiency. I should be pleased to hear further from you
if any good results accrue from phosphate feeding of the cattle."

With reference to the two important points raised in the above reply, it is
to be noted that (1) the conditions are not restricted to the crossbreds only, as a
few cases of the same condition have been seen in several villages in Sindh
and also in two buffalo calves at Quetta, and (2) bone meal, lime and potassium
iodide have been added to the fodder without any apparent results.

The circumstances of the origin of amaurosis would make one suspect some
disturbance of central origin due to an animal or vegetable toxin, bacterial infec-
tion or impaired circulation during intrauterine life. For the last four or five years,
vaccination against abortion has been practised on all the heifers and newly
purchased animals, but the condition existed at the Farm even prior to the intro-
duction of this vaccination and hence the vaccine can scarcely be incriminated.

The influence of the amount of moisture and temperature of this locality on
the development of Mendelian characters has to be examined. It is
said that there is a deficiency of phosphates in the forage at Quetta and if
it is so, phosphate therapy should be beneficial. It is understood that there
occurs in man a peculiar night-blindness (Hemorolopea) which readily responds to
phosphate, treatment. A similar condition of "night-blindness "(nyctalopia) is
known to occur in the Madras Presidency and Raghavan and Thiagaraj (1920)
consider that severe sunlight and errors in diet are probably the causal factors in
this condition. Defective hormonic secretion may also be involved. Lethal
factors like those in the production of earless sheep [Wriedt, 1921] and semilethal
factors as in cases of microphthalmia, coloboma and glaucoma in a certain breed of