SIXTEENTH ANNUM. MEETING. 49 



small, are nevertheless outside the limits of error of analysis, 

 and must, like those of the salts, represent actual changes in the 

 composition of the liquids. 



The experiments give no reliable data for the determinations 

 of the absolute increase and decrease of the liquids and their 

 constituents, so that it is imposible to say with entire certainty 

 whether there was or was not an actual gain of protein or fats 

 or carbohydrates. It would seem extremely probable however 

 that the liquids received and retained small quantities of these 

 materials from the flesh (bodies) of the animals. 



CHANGES IN THE COMPOSITION OF THE WHOLE SHELL-CONTENTS, 

 FLESH AND LIQUIDS. 



4. Comparing the average percentage composition of the 

 total shell-contents before and after floating in the two experi- 

 ments, it appears that: — 



„,, ^ - Before After 



Ihe percentages of Dialysis. Dialysis. 



Water rose from 85.2 to 87.1 



Water-free substance fell from 14.8 •' 12.9 



Total loo.o loo.o 



Protein (N. X. 6.25) fell from 6.8 '• 6.5 



Fats, (ether extract) fell from 1.4 " 1.2 



Carbohj'^drates, &c., fell from 4.3 " 3.7 



Mineral salts, (ash) fell from 2.3 • 1.5 



Total water-free substance 14.8 12.9 



After so much detail, I ought perhaps to simply summarise 

 the results in a few words and close. But one or two matters 

 call for brief notice. 



If the changes in composition of the oysters in Hoating were 

 due to osmose or dialysis alone, we should expect simply a gain 

 of water and loss of salts (and perhaps of carbohydrates). But 

 the flesh seems to have lost a little carbohydrates and fats and 

 probably protein also, along with the salts, while it was absorb- 

 ing water. A way in which this may have come about is sug- 

 gested by my colleague. Prof. H. W. Conn, who calls attention to 

 the fact that some mollusks, when irritated, produce an extremely 



