276 FRANCIS H. Hf^RRICK 



liable to adhere to some of the increments, and has been de- 

 tected in one or two instances , but the chief use of the salivary 

 glue is in the wafer sometimes placed on the twig support 

 {w. fig. 1 6). The saliva of the hummingbird, when dried out, 

 becomes hard, brittle, and transparent like gum Arabic; when 

 wet with cold water it swells and is opaque, but does not per- 

 ceptibly dissolve, or at least not for a long time. No impression 

 seemed to be made on bits of this substance experimented with, 

 after immersion for several days, but in hot water solution is both 

 prompt and complete. 



The ruby throat's nest (see especially No. i of table V) is 

 often so perfectly modelled, that it appears as if pressed in a 

 mold and stamped out of soft felt or papier mache, so true and 

 even are its outer and inner walls and so perfect the rim of the 

 cup (see figs. 15, 16 and 18), the only irregularity being seen at 

 the base where the twig was enveloped. In this fine specimen 

 of the hummer's work the whole outer surface is well encrusted 

 with bits of a thin gray lichen down to the very brim, which is 

 curiously bent inwards or overhung (fig. 16). The lichens are 

 treated rather indifferently, being laid now with light gray 

 face, now with brown underside uppermost (fig. 15), but they 

 are attached uniformly throughout with spiders' silk, and so 

 far as can be determined with nothing else. 



Eighty years ago a controversy was started in England on 

 the nest building habits of the hummingbirds, Audubon having 

 affirmed that the ruby throat of America glued the lichens in 

 place by means of saliva. Charles Waterton, his great and 

 unreasonable adversary at that time, maintained that this was 

 impossible, since the very first rain would undo the work of the 

 salivary gland. 



Audubon's account of the ruby throat's nest which was chal- 

 lenged by Waterton, w^as as follows:^' "the external parts 

 being formed of a light gray lichen found on the branches of 

 trees, or on decayed fence-rails, and so neatly arranged round 

 the whole nest, as w^ell as to some distance from the spot where 

 it is attached, as to seem part of the branch or stem itself, 



^* Op. cit., vol. 1, p. 25. For Waterton's attack, see "Mr. Audubon and his 

 work, the Biography of Birds." Loudon's Magazine of Natural History. London, 

 1834, vol. vii, p. 67-74, followed by four distinct articles, the third on the Hum- 

 mingbird (p. 67-74). 



