42 
BUI.I.ETIN OF THE BUREAU OF FISHERIES. 
position of the fleshy ridge and flaps of skin are such, also, that a fish in forward loco- 
motion forces water through the nostrils. A dogfish is, therefore, whether in motion or 
at rest, constantly receiving through its nasal capsules a current of water. 
EXPERIMENTS WITH FUNDUEUS. 
The olfactory apparatus of the killifish, like that of the catfish, consists of a pair of 
sacs each provided with two apertures, one anterior, the other posterior. The anterior 
olfactory aperture is just above the upper lip and dorsal to the angle of the mouth. 
It is a small roundish opening not unlike one of the pores of the lateral line system and 
is on the summit of a low elevation. The posterior aperture is an elongated slit some- 
what dorsal to the anterior limit of the eyeball. The mouth of the posterior aperture 
is partly occupied by a valve-like fold of skin. 
If the quiescent head from a freshly killed Fundulus is examined in water, no 
motion is observable about the olfactory apertures. Suspended carmine is not carried 
into them nor discharged from them; in other words, there is no evidence of a ciliary 
current passing through the olfactory sacs such as is so easily demonstrated in the 
catfish. If a head in which the respiratory movements of the gills are still in progress 
is examined, well-marked currents can be demonstrated in the olfactory organs. Sus- 
pended carmine is taken in at the anterior aperture and discharged from the posterior 
one. With each respiratory movement, the valve in the posterior aperture opens, a 
small amount of water is discharged, and it then closes. This passage of water through 
the olfactory apparatus is apparently due to the changes of pressure produced by the 
rhythmic activity of the muscles of the gills probably acting in conjunction with valves 
within the olfactory sacs. The movement of the valve at the posterior aperture follows 
exactly that of the respiratory apparatus and its automatic character is obvious from 
the fact that if an anterior aperture in an active fish is closed by having its walls stitched 
together so that no current of water can enter the sac at that point, the posterior valve 
of the same side ceases to pulse, though that of the other side continues in normal 
activity. If, now, the closed aperture is reopened by removing the stitches, the valve 
previously quiescent begins again to pulse. Thus, though Fundulus has no continuous 
current through its olfactory sacs, such as the catfish has, it does have a well-developed 
intermittent current that is not inappropriately designated as respiratory, though this 
current is in no direct way concerned with the respiratory function. Apparently as 
long as the gill muscles of Fundulus carry out the respiratory movements, currents of 
water run through the olfactory sacs. 
As a preliminary test to ascertain whether Fundulus could discover hidden food 
or not, packets of cotton cloth containing dogfish meat wrapped so as not to be visible 
and packets made of nothing but cotton cloth were hung in an aquarium in which there 
were a number of hungry Fundulus. After the packet had been thoroughly soaked 
in the sea water, the reactions of the fishes to them were watched. The packets with- 
out meat were occasionally approached and seized, but soon dropped. Those that 
contained meat were sooner or later surrounded by most of the killifish, which carried 
