670 TRANSACTIONS OF SECTION I. 
derive great pecuniary benefit from the existence of knowledge which would put 
us in a position to guide him in such difficulties. 
Sexual Characteristics.—Almost every text-book on animal husbandry which 
has appeared in the last hundred years tells the reader that he should choose a 
sire showing ‘male character,’ and that such character denotes fecundity, &c. ; 
but the information as to how such character may be recognised is very scanty. 
It seems necessary to attract the attention of the trained zoologist to such a 
question to make further progress in our knowledge. For if external indications 
of these faculties exist, it must be worth while defining and describing their 
appearance; if they do not exist, frequent mention of them in text-books only 
adds to the already difficult task of learning to judge stock. 
Periodicity.—The practical man has many views upon this point. As many 
of the views held and expressed are often contradictory to one another, and as 
the matter is of great commercial importance, it would seem worthy of further 
investigation. 
The Correlation of Fecundity and Productivity.—it is often held by those 
having charge of milch cows that conception will not take place until any 
abnormal flow of milk has ceased. The writer’s own experience among poultry 
at one time led him to believe that hens laying a very great number of eggs 
often failed, through the eggs being ‘clear.’ to reproduce themselves in great 
numbers. Both these points seem worthy of further investigation. Even such 
points as the relative profitableness of a crop of twin lambs, compared with a 
fall of ‘singles,’ or the advantage of large and small litters of pigs, ought not 
to be left severely alone as they have been in the past. 
It seems to the writer important for this meeting to discuss the part played by 
environment, as well as by individuality, in these and all other matters of the 
kind, for only too often in the past even the scanty data available have been 
obtained from foreign breeds of live stock living in countries and under con- 
ditions other than our own. 
(u) The Effect of Reproductive Cycle on Glycogen and Fat Metabolism in 
Crustacea. By GEorFREY SMITH. 
In all animals reproductive and growth cycles are probably correlated with 
metabolic changes in various internal organs. In a large Crustacean, such as 
Carcinus meenas, it is possible to show that the ‘liver,’ which corresponds to 
almost the entire digestive and metabolic apparatus of the higher animals, varies 
greatly in its composition, according to the condition of the crab in respect to 
two functions—moulting and reproduction. The composition of the blood also 
varies in the same way. 
If we take crabs with soft shells which have quite recently moulted and 
determine the percentage of fat and glycogen in the liver, we find a compara- 
tively small amount—from 0°4 to 05 per cent. glycogen, and 5 to 10 per cent. fat.? 
The blood is colourless, and yields a small percentage of fat—-about 0°05 per cent. 
If we take large male crabs with hard shells which are in an intermediate 
period between two moults, we &nd a higher percentage of glycogen—one to two 
per cent.—in the liver, and a larger quantity of this substance under the skin, 
especially as the crab approaches the period of a fresh moult. The amount of fat 
in the liver is variable, with an average of about 10 per cent. The blood is 
generally coloured pink, due to the presence of tetronerythrin which is deposited 
-in the skin. The percentage of fatty material in the blood is about 0°08 per cent. 
If we take female crabs which are maturing their ovaries preparatory to breed- 
ing, we find the liver is richly supplied with fat (13 per cent.), and has a fair 
quantity of glycogen (1 per cent.), but the most striking feature is that the 
blood is bright yellow, owing to the presence of Intein, the yellow substance of 
the yolk which is being formed in the liver and transferred across the blood to 
the ovary. Analysis of the yellow blood of females shows a very high percent- 
age of fatty material—about 0:2 per cent.. or more. After the eggs have been 
shed the blood becomes colourless again. These internal changes, which differ so 
* Determinations of fat by Leathes’s method, of glycogen by Pfluger’s. 
Cay 
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