Record. xlvii 



November 18, 1912. 



President Engler in the chair ; attendance 31. 

 Professor James F. Abbott addressed the Academy on 

 ** Permeability of Animal Membranes." 



The "Fiddler Crabs" of the genus Uca accommodate themselves 

 readily to immersion either in fresh or salt water, or to life in the 

 open air. 



This is due to a special mechanism for storing water in a capacious 

 gill-chamber. When the gill-chamber is opened and rinsed out, they 

 do not live longer than four hours in pure distilled water. Under 

 such circumstances they gain in weight by the absorption of water, 

 and lose salts to the surrounding medium by diffusion. They will 

 live indefinitely in a mixture of NaCl and KCl of much lower concen- 

 tration than that of sea water, although either salt is toxic by itself 

 in the same concentration. 



Dr. C. H. Turner gave a short talk on ' ' The History of 

 an Orphan Colony of the Paper-Making Wasp, Polistes 

 pallipes. ' ' 



A colony of this wasp, consisting of nine capped cells containing 

 pupae and fifteen open cells containing larvae, had been deprived 

 of its "widow mother" and transferred to an insectary. This paper 

 was a discussion of some incidents in the life of the wasps that 

 emerged from the cells of that nest. The following conclusions were 

 reached : 



1. These wasps, which had never seen their mother nor associ- 

 ated with other wasps, performed all of the ordinary activities of 

 such wasps except egg-laying and paper-making. 



2. Large larvae that had nearly completed their larval, after 

 fasting for eight days, then feeding on honey for two days and on 

 their normal diet for the remainder of their larval life, spun normal 

 cocoons and emerged normal wasps. Young larvae when submitted 

 to this treatment died. Two large larvae after fasting for eight days 

 and feeding on honey for two days, wove normal cocoons and 

 emerged normal wasps. This result was a surprise, for Pabre's 

 experiments on several different wasps (not of this species) has 

 caused the belief that hymenopterous larvae that feed on insect food 

 will die if fed honey. 



3. After being restricted to a honey diet for several days, these 

 wasps became cannibals, upcapping a pupal cell and feeding on the 

 contents of the pupa. 



4. From the first the wasps were so tame that they would ac- 

 cept honey or insect food when offered them on glass rods, steel 

 spatulas or the fingers. 



5. Lepidopterous larvae captured for food are not stung. Grasp- 

 ing the caterpillar with her forelegs, the wasp rotates it on its longi- 

 tudinal axis and gradually elevates the insect while she malaxates 

 the posterior end until her jaws are filled with a ball of pulpy 



