104 



W. C. ALLEE. 



the students' attention to Ephelota and Acineta, the Suctorians 

 found attached to old colonies of Obdia. 



In the identification of protozoa found in the field, it has been 

 found desirable to ask the student to classify as far as possible ; 

 after the order, identification is given or checked by the instructor. 



Porifera. One day, lecture and laboratory. In addition to 

 the more usual study of Lcucosolenla and Grant-la, students per- 

 form H. V. Wilson's experiment 1 on the dissociation of Micro- 

 done cells. After squeezing these through miller's bolting cloth, 

 identifying the cells and watching early stages of the plasmodium 

 formation, the slides are put out in a live car under the wharf 

 and taken in for inspection at the end of the course almost six 

 weeks later. Living Grantia are sectioned and choanocytes and 

 flagella studied in the normal condition. In order to make this 

 successful the material is not exposed to the air even momentarily 

 until it is sectioned, and then for as short time as possible; the 

 Grantia is freshly collected and the razors very sharp. 



Coelenterata. Four days, lecture and laboratory. In 1919 and 

 1920 the work on Coelenterata was begun by starting experiments 

 on regeneration in Tubularia. The attention of the class had pre- 

 viously been called to the recent paper of Garcia-Banus and the 

 conflict between that report and the commonly accepted ideas on 

 Tubularia regeneration. 2 Data were collected each day under the 

 personal supervision of some staff member who inspected each 

 piece of Tubularia and final results were tabulated on the black- 

 board. The results for 1919 are quoted by Hyman 3 (p. 358) and 

 were supported by the data of 1920 and both confirm the results 

 obtained by Child* and Hyman rather than those of Garcia- 

 Banus. Needless to say, class interest in this experiment was in- 

 tense, particularly among the more advanced students. 



The work on the Hydrozoa includes time spent on the structure 



1 Wilson, H. V., " Development of Sponges from Dissociated Tissue Cells," 

 Bull. U. S. Bureau of Fisheries, 30, 1910. 



2 " Is the Theory of Axial Gradient in the Regeneration of Tubularia Sup- 

 ported by Facts?" Jour. Exp. Zodl., 26, pp. 265-275. 



3 " The Axial Gradients in Hydrozoa. III. Experiments on the Gradient 

 of Tubularia," BIOL. BULL., 38, p. 358. 



4 " An Analysis of Form Regulation in Tubularia," Arch. f. Entw'lungs- 

 mech., 24, pp. 128. 



