36 C. M. CHILD. 



of the oblique surface and latest on the most proximal portion 

 (Child, '04^^, pp. 193-205, Figs. 1-6). At least a part of this 

 difference is due to the difference in level of the most distal and 

 most proximal portions of the oblique surface, but in the paper 

 referred to it was shown that the marginal tentacles appear earlier 

 on the most distal portion of an oblique end and later on the most 

 proximal portion than on transverse ends at these two different 

 levels. These and other results led me to suggest that perhaps 

 the currents which pass orally along the inner surface of the body- 

 wall in each interseptal chamber might, as well as the general in- 

 ternal pressure, be a factor in tentacle-development (Child, '04^, 

 pp. 193-205). 



The results of experiment on oblique pieces in C. astuarii are 

 similar : part of the records for one series is given here. 

 Series jj. 



September 75, igo^. — I. The oral ends were removed from 

 four specimens by oblique cuts through the oesophageal region 

 {bb. Fig. I). 



II. The oral ends were removed from four other specimens by 

 transverse cuts as nearly as possible at the same level as 

 the most distal portion of the oblique cuts {aa, Fig. i). No 

 control was made for the lower level of the oblique surface 

 because the rapidity of tentacle-formation on transverse surfaces 

 is not very different at these two levels. The history of one of 

 the oblique pieces and one of the controls is given. 



September ly. — The cut ends in the oblique pieces I. and the 

 control II. were closed : tentacles were not visible in either, but 

 the body-wall was becoming thinner in the most distal portion of 

 the oblique piece (Fig. 6, diagrammatic longitudinal section). 



September 20. — I. Marginal tentacles about 2 mm. long on 

 the most distal portion of the oblique surface and decreasing in 

 length from this point to zero about half way between the 

 extreme distal and proximal portions of the disc. The most 

 proximal portion of the disc shows no preparation for tentacle- 

 formation as yet. Fig. 7 is a diagrammatic longitudinal section 

 and Fig. 8 shows one side of the disc. 



II. Marginal tentacles just appearing about the whole margin 

 of the disc : 0. 5-1 mm. in length (Fig. 9). 



