FOOT—DISSECTION OF AN AYLESBURY DUCK. 201 
the large amount of organic matter it contains. It may be remarked 
that the blood of the duck in particular is rich in solid constituents, it 
has been found to possess the largest amount of solid constituents among 
specimens of the blood of nineteen animals analyzed by Dumas and 
Prevost.* Another cause of this phenomenon may be that the active 
oxidation, which is characteristic of this class, tends to be constantly 
converting the albumen of their blood into fibrine. According to Thack- 
rah,} the period required for the coagulation of the blood of the duck 
is from one to two minutes; of fowl, from half a minute to a minute and 
a-half; while in pigeons it occurs almost instantaneously ; whereas in 
the ox it requires from two to twelve minutes; in the horse, from five 
to thirteen ; and in man, from seven to sixteen minutes. 
With regard to the very remarkable size of the testicles, I am not 
able to say whether the enlargement is normal or abnormal. I am not 
aware of the maximum size to which these glands can attain in a highly 
bred and well-fed drake, such as this was; but I am inclined to think 
that these organs must exceed their usual dimensions, although, as I 
observed before, there were none of the ordinary indications of disease 
in the glands themselves or their neighbourhood. I regret that no mi- 
eroscopical examination of theirinternal structure was made, 
In the same month of the year I examined the body of a very hand- 
some Dorking cock for Mr. Williams; it had died of apoplexy, and was, 
I think, a heavier bird than the drake; these are its testicles preserved ; 
they weighed together 6 drachms ‘34 grs., a little more than three-quar- 
ters of an ounce, less than a fifth of the weight of the drake’s testicles; the 
right one measured one inch and three-quarters in length, seven-eighths 
of an inch in breadth ; the left, one inch seven-eighths in length, an inch 
in breadth. Compared with the testicles even of an ostrich, those of the 
drake have the advantage in size. The right testicle of an ostrich, which 
died in the month of January, 1864, measured three inches in length, 
one and three-quarters in breadth; the left, three inches and a-half in 
length, one and three-quarters in breadth. They are also more than 
double the size and weight of the human testicles, which average each 
about six drachms, and measure from an inch and a-half to two inches 
in length, and nearly an inch from side to side. It must, however, 
be borne in mind that the periodic increase in birds of these glands is 
very surprising ; and if the month of June be the time of maximum 
size for the drake, much of the hypertrophy will be accounted for. 
On the subject of the periodical increase of the testicles in birds, 
John Hunter remarks :—‘‘ If a cock sparrow is killed in the winter, 
before the days have begun to lengthen, the testicle will be found very 
small; but if this organ is examined at different times in other spar- 
rows, as the warmth of the weather increases, and if this examination 
is continued to the breeding season, the difference in the size of the 
* Simon, ‘‘ An. Chem.,” vol. i., p. 349. 
+ Flint, ‘‘ Physiology of Man,” vol. i., p. 144, note. 
