3l6 BULLETIN OF THE BUREAU OF FISHERIES. 



By pressing the lips of the spermatic receptacle of a female with internal eggs 

 nearly ripe, I have observed the sperm in a thick grayish mass which gave up its cells 

 freely to sea water. This at all events suggests the possibility that the lobster herself 

 is the direct agent in emptying her receptacle. In any case it is highly probable that 

 the sperms are directed by chemotropism to the eggs after reaching the water. Nothing 

 is known by direct observation of the phenomena of fertilization up to this point. 



What are the locomotor organs by which the sperms leave tlje sperm receptacle or 

 by which they seek and find the eggs in the brood chamber? In our search for an 

 answer to this question we must remember that the lobster lies upon her back when the 

 eggs are laid, so that the force of gravity is a bar rather than a help to the movements 

 of the sperm at this critical period. We may assume first that in leaving the receptacle 

 the locomotor organs of the sperm cells are the rays or processes, which I showed in 1895 

 to be rigid in the testes but limp in the receptaculum. This movement is probably 

 amoeboid in character, consisting in the lengthening and shortening of the protoplasmic 

 element of the process which flows from the neck of the cell. As with the amoeba a 

 solid support is necessary for the process of locomotion to be effective, for according 

 to a recent observer this animal probably- draws itself along by the adhesion of its 

 pseudopodia to the surface over which it creeps. 



How does the cell make its way through the water to the egg? No satisfactory 

 answer can now be given, but if Bumpus was not entirely mistaken in his report of 

 movements of the lobster's sperm, as quoted above, we might plausibly suggest the fol- 

 lowing solution, which is of course purely hypothetical. Upon reaching the water the 

 plug of the capsule is loosened and falls out. Water then enters and fills the inner tube. 

 This water is subsequently ejected by contraction of the vesicle, and the cell is drawn 

 forward by inertia. It should be added here that in some forms (Eupagurus) the cap- 

 sule is covered by a thin protoplasmic layer, and that in this membrane contractile fibers 

 are sometimes seen; transverse rings can be demonstrated in the lobster. The action 

 is supposedly recurrent. The processes direct the cell, as do barbs the arrow. The 

 eggs are big targets, and the moment one is struck orientation of the sperm upon its 

 surface begins. 



At this point speculation gives way in a measure to direct observation, and I return 

 to the account of Koltzoff {172) who, like other observers, was unable to see the minute 

 sperm enter the huge opaque egg. Disclaiming the ability to give a complete account 

 of the movements of the sperm cells, he says: "My observations and experiments can 

 naturally clear up only certain phases of these processes, and a whole string of hypo- 

 thetical conclusions is needed to unite them into a harmonious whole. " 



Contact with a large and possibly moving body, or thigmotaxis, seemed to furnish 

 the most powerful stimulus to the cell processes, which have been observed to shorten 

 and lengthen, though not to the extent of more than one-tenth of their length. Once 

 in touch with the egg the sperms begin to orient themselves in such a way that the cell 

 comes to stand upon its thin elastic processes as upon a tripod, so that the head is placed 

 in direct contact with the surface of the egg. The elastic process or processes in con- 



