isi-'*! Gee: Behavior of Leeches 239 



Next, the Hemiclepsis was placed in the dish with fifteen 

 yonns of the smaller and more active forms. After four days 

 of this comhination had elapsed, none of the young: of Glossi- 

 phonia showed any more fondness for the foreign foster-parent, 

 as evidenced by permanent attachment, than its young had evi- 

 denced for Glossiphonia. While none of the .voung of Hemiclepais 

 were observed to attach themselves to the adult Glossiphonia, 

 the reverse condition was noted in a few eases. The young of 

 the glossiphonid in crawling about in the dish would come in 

 contact with the body of Hemiclepsis and would sometimes attach 

 themselves to the dorsal surface. The adult specimen would 

 under such a condition soon come to rest, the lateral margins of 

 the body closely pressed against the bottom of the dish. In this 

 wa.y the young glossiphonids were prevented from attaching 

 themselves for permanent lodgment, and would soon leave the 

 body, and finally join the collection already made by the other 

 young in the angles of the dish. 



Thus on the part of the parent forms no evideiu'e of a jiarental 

 instinct seemed present. There is recorded at least one species 

 of Glossiphonia (BoLsias. 1911; Houghton, 1863) that seems to 

 lay its eggs on some foreign ob.ject, and to remain over them 

 after deposition until they are hatched. Gibbs (1897-1899) notes 

 a similar behavior in the skate-leech. Pontobclella muricata. Whit- 

 man (1878) says of Clepsine marginata: "The worm remains 

 over the eggs, for the purpose of protection only, till they hatch. 

 The young, soon after exclusion, become fixed to the ventral side 

 of the parent, and are thus borne until they are fully developed 

 and able to provide for themselves." 



In these cases, there does seem evidence for at least a rudi- 

 mentary "brooding" or "incubating" in.stinct. Unfortunately, 

 none of these forms was available for experiments in this con- 

 nection. The chief eagerness for protection in Glossiphonia stag- 

 nalis and Hemiclepsis occidentalis was manifested on the part of 

 the young in the form of stronglj' positive thigmotactic reactions. 

 The discrimination on the part of the young of Hemiclepsis for 

 the parent form of their own species as contrasted with that of 

 a related one is very probably much akin to the recognition of 

 the adult forms for their own species in the process of spermato- 

 phore deposition. 



