THE BRITISH ASSOCIATION. 
249 
among the species of crocodiles, from the eiyor of some naturalists 
regarding the young and the adult as different species — an error arising 
from the short and rounded form of the face when first hatched. In 
process of growth, however, the muzzle elongates, and the hones increase 
in size for supporting the teeth. The author remarked that this well 
illustrated the necessity of studying all the kinds of animals in every 
stage of their growth. No species could he said to have been properly 
observed until all these circumstances had been duly examined and noted ; 
and though the notice of a single individual, or state of an animal, was 
certainly of value, it could only be regarded as a sign-post, indicating the 
existence of an animal which required further study and examination. 
Dr. Gray went on to point out that great confusion had arisen among the 
species of Crocodiles and Alligators. The character of the “ teeth fitted 
into notches in the margin” was one, however, which was peculiar to 
crocodiles, and not common to both ; nor is the African crocodile found in 
India, as supposed. 
R. Garner, F.L.S. : “ On Pearls : their Parasitic Origin.” Mr. Garner 
had examined the pearls formed in the Conway and Lancashire mussel ; 
not the beautiful pearls of the Alasmadon, from the Upper Conway, at 
Llanrwst, but those of the salt-water mussel. He attributed the same 
origin to all pearls, viz., the deposit of eggs by a minute species of 
Distoma, causing their formation much in the same way as galls are 
formed in plants. 
Dr. Cobbold was not ready to accept Mr. Garner’s explanation, for he 
had not seen the Distoma within the pearl, nor investigated the anatomy 
of the parasite ; and knew not, therefore, whether it was a perfect 
Distoma or a larva. 
Mr. Garner replied that the pearls of Alasmadon are not diseased ova, 
for it has its ova in the foot and gills, where the pearls do not occur ; nor 
are they produced in the renal organs. They might be produced by 
grains of sand, &c., but then such foreign bodies could not get access to 
the mantle, as it is attached all round to the shell ; and on splitting a 
pearl no grain of sand is found, but a little dark-coloured animal matter, 
which he considered to be the remains of the Distoma, its exuviae, &c. 
In the Lancashire mussels, the Distoma was always to be found as a little 
yellow speck (to the naked eye) enclosed in a condensed cellular envelope, 
and sometimes might be found in a calcifying state. He did not think he 
was called upon to follow out the anatomy of the parasite. 
Professor Rolleston, F.R.S. : “ Diastase in the Saliva, and its Action 
upon Starch and Inuline.” Inuline, a kind of starch found in the dahlia, 
artichoke, &c., differs from true starch in not being changed into sugar by 
the converting agency of the diastase contained in the saliva, unless, 
indeed, it contains sugar at first. Moreover, the saliva of infants contains 
so small an amount of diastase, that even common starch is inconvertible 
by it, and therefore innutritious. Important practical results follow from 
this ; first, that artichokes cannot be used as a substitute for potatoes, 
since they contain inuline instead of starch ; and second, starch foods are 
useless in the early months of infancy, since the salivary diastase at such 
a period is inactive. 
VOL. II. — NO. VI. 
S 
