I So HOLMES. [VOL. II. 



shock of the operation has a very temporary effect, for in a 

 few hours the animals behave with their usual activity. Meat 

 brought in contact with the second antennae is generally not 

 seized. This, however, is not always the case, for in several 

 instances I have found that contact with the second antennae 

 causes the grasping reflex. I was inclined at first to attribute 

 a certain olfactory sensibility to the second antennae, but I 

 found later that the animal reacts about as well to olfactory 

 stimuli when both antennae are removed as when the second 

 alone remain. In specimens with both antennae removed near 

 the base, leaving only the first joint of the peduncle of each 

 pair, there was no reaction to food placed in what would have 

 been within easy reach of the antennae before their removal. 

 If a piece of meat is placed about 2 mm. from the mouth of the 

 amphipod, it is generally allowed to remain untouched for 

 several seconds and then suddenly seized and eaten. The 

 morsel is seized by the gnathopods and at the same time 

 bitten at with the mouth parts. The reaction is not an imme- 

 diate one, such as is brought about by contact of the anten- 

 nules with food. It appears to be necessary for the food to 

 remain awhile in close proximity to the animal before its edible 

 nature is perceived ; when this occurs the seizing takes place 

 quickly enough. I have tried to induce the animals to take 

 bits of substance of the general appearance of fragments of 

 meat and brought very close to the mouth parts, but they are 

 apparently able to distinguish, before any contact with the 

 object occurs, whether or not it is of an edible nature. It is 

 true that Amphithoe often grasps objects that lie near by, 

 pulls them back, and incorporates them into the structure of 

 its nest, and it might be inferred that the seizing of meat lying 

 close to its mouth by a specimen with both antennae removed 

 is an expression of the nest-building instinct to seize any small 

 object within reach for building material. The reactions in 

 the two cases, which I have observed many times, differ. An 

 object used for the construction of the nest is reached for and 

 pulled back to the nest and not as a rule brought in contact 

 with the mouth. A bit of meat is grabbed at and bitten at in 

 the same act. This difference in reaction and the fact that 



