450 THE NERVOUS SYSTEM. 
fungiformia and their trabecule, and the increase of the pro- 
cerebral lobes, which I take to be the lateral lobes of the 
middle protocerebron of Viallanes. This structure in the 
higher Insecta, as in the Blow-fly, assumes a new import from 
its remarkable connections and its cerebroid character. 
c. Details of the Structure of the Brain of the Blow-fly Imago. 
The brain of the imago of the Blow-fly, and under this term 
I include all the cephalic nerve centres, agrees in structure 
very closely with that of all the higher Insecta. It is formed 
upon the same ground plan as that of the Arthropoda in 
general. 
Size of the Brain as compared to the Body-weight.—The propor- 
tionate bulk of the brain in insects to that of the body has 
been frequently estimated, and the following table, taken from 
Graber [10], represents the results arrived at. The bulk of 
the brain is: 
In Dytiscus sooo Of that of the body. 
In Melolontha vulgaris 3'5o: 
In Ichneumon Sp. (?) sdo- 
In the Honey-bee =$y- 
In the Ant zi: 
In the Blow-fly I find it to be z}»- 
These numbers do not, however, fairly represent the propor- 
tion owing to the large air-spaces of the body. I have en- 
deavoured to determine the relation of the weight of the 
brain as compared to that of the body in the Blow-fly, and it 
may be set down approximately at between z}q and shy of the 
body-weight. Taking the Bee and Wasp as standards of com- 
parison, its proportionate weight is less than in these Hymenop- 
tera, in which I should estimate it as between yjp and gp of 
the body-weight. Cuvier gave an estimate of the proportion 
of the weight of the brain to that of the body in several groups 
of Mammals, and he found the weight of the brain in the 
larger carnivora varied between yjy and 3 $y of the body- 
weight. In small birds it is about ten times greater, or from 
