IO6 W. C. ALLEE. 



last half of the day of the Ccelenterate group is spent on Pleuro- 

 bracJiia which Mr. G. M. Gray preserves in life-like transparency. 

 These are studied in the original preservative, rather than in 

 water. 



PlatylielniintJics. Three days, lecture and laboratory. This 

 study begins with locomotion and feeding reactions of fresh-water 

 planaria, and regeneration experiments are started. The animals 

 are kept in pond water. We introduce the class to living Syncc?- 

 lidiurn or Bdelloura from the gill books of Linmlus. These have 

 lost their pigment and the structure even to flame cells, is visible. 

 Cross sections have been used of late years to give a better demon- 

 stration of the relation of the proboscis to other structures. The 

 Cestodes are studied with living Crossoboihrium when sand 

 shark spiral valves are available ; if these are not to be had, Rhyn- 

 cobothrhnn and Calliobothrium* from the spiral valve of the dog- 

 fish are substituted. Flame cells are readily seen in the scolex 

 of any of these. The encysted scolex of Otobothrium 2 found in 

 the muscles along the vertebrae of the butterfish gives an example 

 of the everted pleurocerous stage characteristic of the Tetrabo- 

 thridia. In 1921 a study of embryonic stages of Rhyncobothnum 

 was added to supplement the work on the encysted scolex of 

 Otobothrium. The following stages were studied: (i) The 

 freshly laid eggs ; (2) eggs in which the hexacanth embryos were 

 developed; (3) emergence of embryos from egg case; (4) free 

 swimming hexacanth embryos with ciliated embryophore; (5) 

 embryo from which the embryophore has been torn off. Direc- 

 tions for obtaining this material as worked out by Dr. Bowen are 

 given in the appendix (i). 



A half day is spent on Tctrastema, the little nemertean from 

 pilings. These are secured by allowing scrapings taken about 6 

 A.M. to stand for three hours in fairly deep glass jars filled with 

 sea water ; the nemerteans can be picked up with a pipette and a 

 lighted candle held by the jar just below the water level makes 

 them more easily recognized. Scrapings spoil if allowed to stand 



1 Linton, E., " Notes on the Entozoa of Marine Fishes of New England," 

 U. S. Comm. of Fish and Fisheries, Comm. Report, 1886 and 1887. 



2 Linton, E., " A Cestode Parasite in the Flesh of the Butterfish," Bull. 

 Bur. of Fisheries, 26, 1906. 



