16

Experiment I—contd.

B.

       Rats and fleas were put in various positions on the floor—the rats in cages
and the fleas in test-tubes with the glass end removed and both ends covered by
some netting to allow of proper diffusion of the gas.

POSITION. RATS. FLEAS. REMARKS.
Dead. Sick. Alive. Dead. Alive.
On the floor     ... 1 2 ... ...  
  4 feet from floor   2 ... 1 ... ...  
  7            do.     ... 1* ... All ... * Escaped, but found
   outside sick.
10            do.     ... 1 2 All ...  
15            do.     .. 1 2 All ...  

C.

       Twenty fleas were placed in each of four cages,—two containing sand at
the bottom and two bran. At the end of 51 minutes the cages were examined
and guinea-pigs put into the cages on three separate occasions to recover the fleas.

CAGES. No. of fleas
put into each
cage.		 Result, i.e., recovered alive
after exposure of 55
minutes.		 REMARKS.
Cage No. 1 with
   bran at the
   bottom.		 20 4  
Cage No. 2 with
   bran at the
   bottom.		 20 None.  
Cage No. 1 with
   sand at the
   bottom.		 20 2  
Cage No. 2 with
   sand at the
   bottom.		 20 2  

       For a control to this, see the end of Experiment III.