I04 EDWARD POTTS : 



distinct membranes, of which the inner becomes the velum, 

 and the outer, dividing from the marginal canal towards the 

 centre into eight portions, gathers into these the thread cells, 

 that are, afterward, found so abundantly upon the tentacles." 



It is possible that a few medusae were seen after their first 

 discovery in 1897, say in 1898 or 1899, but no opportunity 

 was found for such observation as was above suggested until 

 May 1 6th of last year. On that morning a bud was doubt- 

 fully suspected, watched during that day and the next, and 

 by 9 p. m. of the 17th the evidence of a coming medusa 

 became convincing. Yet its position on the side of a jar, and 

 in relation to the other members of the group was not such as 

 made possible the determination of the first two points named 

 above. The "microscopical observatory" had not, at that date, 

 been devised, and the best we could do was to stand the jar 

 upon a pile of books before a Welsbach gas light and examine 

 it with a Coddington lens or, later, through the tube removed 

 from a compound microscope and laid across another pile of 

 books. 



This was the situation when, at 9.30 p. m., five of us 

 determined not to lose sight of it during the night ; wherefore 

 one or more were continuously on the watch until 6.30 a. m, 

 of May 18th. The first differentiation of parts had appeared 

 about 9.30 p. m., May 17th, and all hands took part, though 

 without artistic skill or scientific training, in recording what 

 we saw, b}' drawings, the most characteristic features of 

 which I have here preserved. (See Plate III, Figures i to 8). 

 An examination of them will show the first recognizable 

 feature to have been the marnibrium at the proximal extremity- 

 of the bud — bearing upon its summit a circular or spherical 

 figure more or less complete in every figure, though variable 

 in size ; whose meaning must be left to elucidation through 

 other specimens. Above or beyond this there was always a 

 light-cavity of varying size and shape ; and, almost from the 

 beginning, transverse lines were to be seen at the distal end 

 of the bud, suggestive of two membranes ; and, still more 



