1888.] Mr Irvine and Dr Woodhead on Lime Secretion. 311 
ia air, the actual shells were found to weigh from 60 to 90 grains 
each, and to consist of — 
"Water, organic matter, &c., . . 23 '47 
Carbonate of lime, . . . 76 '53 
100-00 
The gross weight of the shells of the twenty-one eggs was 1400 
grains. Deducting from this the water and organic matter present, 
328*58 grains, and the lime in the ash of their food calculated into 
carbonate, viz., 117 grains, we have 954*42 grains of carbonate of 
lime elaborated by the birds from sulphate of lime during the period 
of this experiment. The hens ceased to lay eggs, one of them within 
four weeks after confinement, and the other at the date these experi- 
ments were concluded (about six weeks). We attribute this to the 
weather and to the confinement, not to inability longer to effect the 
decomposition of the sulphate, as, on one of the hens being killed 
at the close of these experiments, a perfect egg was found in the 
oviduct in process of receiving its calcareous covering. 
It occurred to us that the birds might be able to store sufficient 
carbonate of lime to account for the formation of the shells of these 
eggs ; and to determine this point, a healthy laying hen was killed 
(not one of those fed with sulphate of lime), and the viscera care- 
fully removed and the ovaries and oviduct exposed, showing a 
number of ova in various stages of development. The viscera and 
contents, oviduct, blood, &c., were treated with nitro-hydro chloric 
acid, evaporated to dryness, ignited, and the lime determined. 
The contents of crop and gizzard, which had been separated, were 
found to consist of partly digested food and gravel, amounting in 
weight to 300 grains or more ; this was digested with dilute hydro- 
chloric acid. 
The lime found (calculated into carbonate) was as follows : — 
In the whole viscera, heart, liver, lungs, blood,. 
&c., less than, 1 grain. 
In the gizzard and crop, . . . , . 9 '08 , , 
10-08 „ 
(This did not include phosphate of lime, which was present in con- 
siderable quantity.) 
