658 
president’s address. 
directed at a right-angle to the bough, or there may be some 
correlation here with the pectinated toe nail, which is more 
highly developed in the Nightjar than in any other British 
bird. Peculiar structural modifications, or appendages, in 
any animal have their explanation in the domestic economy 
of the species in which they occur. The long legs of the Crane- 
fly and Harvestman, the brush-like arrangement on the 
Glow-worm’s tail, the powder-down tracts of the Heron, 
the palatal knob of the Bunting, the long hind claw of the 
Skylark, and the moustachial vibrissae of the Nightjar are 
all as specially useful to their respective owners as 
is slime to the Snail, a prickly jacket to the Hedgehog, or 
tails and gills to the Tadpole, whilst a larger eye would be 
worse than useless to the underground Mole, and a shorter tail 
a dangerous defect to a Dormouse. 
The popular fallacy that still, at least through its Latin 
name, connects the Nightjar with Goat sucking, is even more 
absurd than the idea of Hedgehogs sucking Cows — each 
wild thing merely being attracted by the lowlier creatures, 
insects or annelids, which hover around, or are frightened 
out of the ground by the grazing or recumbent quadrupeds. 
During the winter months one often comes across small 
masses of an opaque, gelatinous substance lying on the 
banks of the ditches, or in swampy spots on the common, 
the identification of which has puzzled several scientific 
naturalists. In January, 1903, I sent some up to the 
R. H. Society : it was submitted to Dr. Cooke, the fungologist, 
who said that it closely resembled the fungus (Nostoc) which 
often appears after rain, but he could not identify it at all, 
and suggested my forwarding a specimen to some chemist. 
I sent some to Dr. Nuttall of the Cambridge Laboratory ; 
he conferred with Lister and Professor Marshall Ward, and 
reported : “ The mass is chiefly composed of the capsular 
substance of an Alga, what appears to be a Nostoc, but a yeast 
has also been isolated from the mass. Besides this, 1 found 
