438 NATURAL niSrOIlY OF BIRDS. 



of the ' edihlo bird's-ncsts.' Thoy breed in deep caves, fastening their gelatinous nests 

 to the rocky walls. It was formerly the belief that the substance which composed 

 the nests was digested algoe growing on the sea-beach or on the walls of the caves, 

 mixed with the excretion of the salivary glands, but it seems now certain that it 

 consists solely of mucus. Mr. II. Pryer, who recently made a visit to the caves of 

 Gomanton, northern J3orneo, situated in a high limestone cliff twelve miles inland 

 from the head of Sandakan Bay, last year i)ublished an interesting account of the 

 breeding there of Collocaliafucijihnfffi, from which we select the following: — 



" After a rest, I ascended the cliff about four hundred feet ; the ascent is quite per- 

 pendicular: in many places ladders are erected, and in otliers the water-worn surface 

 of the limestone gives a foothold. At this ])oint I found myself at the mouth of a 

 cave named Simud Puti'ii, ». t'., tlie White Cave; the entrance is .about forty feet high, 

 by sixty feet wide, and descends very steeply, widening out to a great size, and having 

 a perpendicular luiexplored abyss at its furthest point. This cave is used by the nest- 

 gatherers as their dweUing-])lace, and at tlie entrance are their platforms of .sticks, 

 one of which was jilaced at my disposal by the head man; it is also the cave by which 

 the great body of the swifts enter. 



"At a quarter to six (p.m.) the swifts began to come in to Simud Putih ; a few 

 had been flying in :ind out all day long, but now they began to pour in, at first in 

 tens and then in hundreds, until the sound of their wings was like a strong g.ale of 

 wind whistling through the rigging of a ship. They continued flying in until after 

 midnight, as I could still see them flashing by over my head when I went to sleep. 

 As long as it remained light I found it impossible to catch any with my butterfly-net, 

 but after dark it was oidy necessary to wave the net in the air to secure as many as I 

 wanted. Nevertheless, they must undoubtedly jiossess wonderful powers of sight to 

 fly about in the dark in the darkest recesses of their caves, and to return to their 

 nests, often built in ])laces where no light ever penetrates. 



"Arising before daylight, I witnessed a reversal of the proceedings of the previous 

 night, the swifts now going out of Simud Putih. 



"In this cave I saw the nest-gatherers at work getting in their crop. A thin 

 rattan ladder was fixed to the end of a long pole and wedged against the rock; two 

 men were on the lailder, one cari'ied a long four-jironged spear, a lighteil candle being 

 fixed to it a few inches below the prongs. By the aid of tliis light a snitalile nest is 

 found, and transfixed with the prongs; a slight twist detaches the nest unbroken from 

 the rock; the spear is then withdrawn until the head is within reach of the second 

 man, who takes tlie nest off the prongs and places it in a ])ouch carried at the waist. 

 The nests of best quality are bound up into packets with strips of rattan, the inferior 

 being simply threaded together; the best packets generally weigh one catty (l^lbs.), 

 averaging forty nests, and are sold at $9 each, the annual value of the nests gathered 

 bemg about 6i'2"),000. These caves have been worked for seven generations without 

 any diminution in the quantity; three crops are taken during the year." 



Mr. J. R. Green, of the Physiological Laboratory, Cambridge, Eng., reported on 

 the nests collected as follows : — 



"The specimen gave no evidence under the microscope of any distinct vegetable 

 structures, and similarly gave no chemical evidence of either cellulose or any other 

 distinctly vegetable jiroduct. All the relations went to prove that the great mass of 

 the substance was mucin, and such microscopic features as were a])parent confirmed 

 the view that the nest was formed of strings of mucus plastered together. The 



