SPAWNING HABITS OF CH/ETOPLEURA APICULATA. 237 



SPAWNING UNDER LABORATORY CONDITIONS. 



It may be that the spawning habit and presumably other behavior 

 of animals under laboratory conditions is not a reliable criterion 

 for normal behavior in nature. This comes out most clearly when 

 all of the factors which influence spawning under artificial condi- 

 tions are considered. 



It may almost be stated as a general rule that sexually mature 

 marine animals are likely to shed their ripe eggs when placed under 

 abnormal conditions. It would seem, therefore, to be a futile, or 

 at least an unnecessary procedure, to attempt to duplicate normal 

 conditions in the laboratory as a means of inducing spawning. For 

 instance, in order to secure the eggs of the small lamellibranch, 

 Cumingia, it is only necessary to take them from the sand in which 

 they live and expose them to the air for an hour or two, where- 

 upon, when placed in a pan of quiet sea-water, they begin to spawn 

 abundantly within half an hour. Eggs may be obtained in this 

 manner at almost any time during the summer, and it is not un- 

 common for every female which is brought into the laboratory to 

 spawn. It is not probable that many of these females would have 

 spawned at these particular times if they had been left undisturbed 

 in their normal situations. 



Consider the case of the annelid, Hydroides. In order to cause 

 them to spawn it is sufficient to break away their calcareous tubes 

 and place them in sea water. Under these conditions they shed 

 their sexual products within a few seconds. Dr. E. E. Just states 

 that it is only necessary to pinch their tentacles or snip them off 

 with scissors to induce spawning. They need not be removed from 

 their tubes. It would appear, therefore, that the spawning of 

 mature sexual products, in these cases, is influenced more by shock 

 than by normal conditions. In fact, the more unnatural the con- 

 ditions are made the better. However, after the shock has been 

 applied, they require to be placed in a quiet situation, and presum- 

 ably the more nearly it approaches normal conditions the better. 



If these data have general significance, we may suppose that 

 experiments which are performed in laboratories upon the behavior 

 of animals, especially with reference to spawning, should be 



