Birds of Celebes: Cypselidae. 
333 
continued for nearly a week, to fix scraps of moss, the commencement of their 
nest, on the painted ceiling of a room, “but failed to get a single piece to stick, 
and so at last gave it up as a bad job”. 
The nests are chiefly formed of the saliva of the birds more or less inter- 
mixed with feathers and sometimes with moss. The high value (as an aphro- 
disiacum) set upon them by the Chinese for soup is well known, and it is said 
that nests of the purest quality — the white ones — are worth their weight 
in silver^). According to Mr. Daly, the white nests of C. fuciphaga are those 
which are gathered before the bird has commenced to lay any eggs, and which 
are composed of clear transparent mucilaginous matter, with very few feathers 
mixed up with them. The next quality is the red or grey nest, partly mixed 
with feathers and in which eggs are sometimes found; the least valuable are 
the black nests, which are much mixed with feathers and sometimes contain 
fledglings. The black nests have been supposed to belong to different species 
or varieties, but Mr. Daly says these nests are those which have been “over- 
looked at the previous gathering and have darkened or deteriorated from expo- 
sure to water and to the atmosphere of the caves. The partial decomposition 
of the mucous matter renders them the least valuable”. 
Bernstein (d 2) has called attention to the enormous development of the 
salivary glands in these birds, especially the glandulae sublinguales. Their great 
size is attained only during the time that the birds are building their nests, 
“after this, even during the laying of the eggs, they atrophy and appear but 
little bigger than those of other birds. At that time (the building time) they 
appear, when the bill of the bird is opened, like two large pads at the side of 
the tongue. They secrete in quantities a thick, adhesive slime . . . resembling 
gum-arabic . . . which can be drawn out of the mouth in somewhat long threads. 
If the end of such a thread of slime is placed on the point of a bit of stick 
and the latter is then turned slowly on its axis, in this manner the whole mass 
of saliva for the moment present can be drawn out of the mouth and even out 
of the orifices of the glands”. As Bernstein found from some tame specimens 
the supply of saliva stands in direct relation to the quantity of food supplied: 
“it was very small, when the birds had gone hungry a few hours”. Bernstein 
came to the conclusion that the giue-like substance of the nest was formed 
solely by these secretions of the bird, and believed that the feathers seen in 
the nest are such as have been caught and stuck by this adhesive matter when 
half dry. Nevertheless, chemical analysis ultimately proved the presence also, 
in addition to the bird’s saliva, of a gumlike substance from an Alga in the 
nests of C. fuciphaga obtained by Fryer in North Borneo (8). That C. fuciphaga 
should employ such foreign substances sometimes or always is not surprising, 
since some other Collocaliae are known to make use of moss, lichens, etc., as 
does C. fuciphaga itself in India (c 2). 
1) In 1896 there were imported into China 3,600 000 edible birds-nests. 
