78 



LUCIUINARI.E AND THEIll ALLIES. 



b 



of the middle rank would be designated by the numbers 1, 3, 5, The eiglith 

 tentacle is numbered 6, and is so plured as to alternate with 2 and 4, and presses 

 against their bases. The ninth is numbered G% and holds the same relation to 2" 

 and -i^ that 6 does to 2 and -4. As tlie numbers increase, the tendency is to widen 

 the <noup, by the development of new tentacles in the neighborhood of the oldest. 

 This is seen in the appearance of 6 and 6% so far away from 5, and so near to 2 

 and 2'. We cannot say positively where the next that are to increase the lateral 

 extension will appear, but we have good reason to think that they will arise alter- 

 nate with 1 and 2 on one side, and 1 and 2^ on the other (see cut 4, p. 45), An 

 inspection of the diagram (see cut No. 4) of the taxis of a full-grown group will 

 assist us in this matter. It is plain enough iicre that the tentacles lying on each 

 side of 1 must have originated wliere they stand, and, according to the method 

 exhibited in the diagrams of young groups, after 2 and 2% and consequently on 

 the distal side of the latter. 



156. The relative age of the tentacles on each side of 1 is not to be seen in their 

 proportional size ; but if we follow the curved rank along the distal side of the 

 group (see cut No. 2, p. 43), we shall find that, as we recede from 1, they decrease 

 in magnitude regularly, until they attain a mvnivrum, at the proximal side, in the 

 last one at each side of the row. This would seem to show quite conclusively that 

 there are two lines of progress in the development of the tentacles ; the one trend- 

 ing centripetally, as indicated by the numbers 1, 3, 5, etc., and the other trending 

 laterally on each side of 1, and following the margin of the umbclla. That those 

 in either of these trends succeed each other in one, two, three order is far from 

 true ; but that those in one trend alternate with those of the other trend in the 

 time of their origin and rate of development, is probably indisputable, judging from 

 the diagrams of the taxial succession of the young groups. What formula ex- 

 presses the taxis in the present case we do not pretend to have discovered, and we 

 must leave it to the determination of more ])rofound taxonomists than ourselves. 

 The diagram of the youngest group (^ 15U) which we have met with would indicate 

 the three ranked arrangement if applied to a plant, the formula of which is -\. 

 In the diagram of nine tentacles (^ 155), this taxis seems to be carri,ed out as far as 

 the seventh (No. 5) tentacle ; but tlie introduction of 6 and 6^ alternate with 2 

 and 4, and 2'' and 4* destroys tlie continuity, and evidently introduces the element 

 of another fornnda. 



156a. From the manner in which the tentacles in the diagram (cut No. 4) of an 

 adult group succeed each other, it is plain that the transverse rows should be num- 

 bered thus, row 1 = No. 1 ; row 2 — Nos. 2% 2; row 3 = Nos. 6% 3, 6 ; row 4 = 

 Nos. 4% 4 ; row 5 = No. 5 ; row 6 = A.\ A«; row 7 = B" ; row 8 = C^ C\ etc., to W\ 

 because, starting with No. 1, we saw in the young (§ 20) that 2% 2, developing next, 

 united across the proximal side of 1, and formed row 2; and since 2% 2 separate 

 3 from 1, No. 3 must be in row 3. Then, again, since 4 , 4 stand in the same 

 relation to 3 that 2% 2 do to 1, it follows that 4% 4 belong to the next row within 

 3, i. e., to row 4; and so 5 succeeds in the next, or fifth row. Thus going inward, 

 toward the proximal side of the group, A\ A" are in row 6, and W iu row 7, etc., 

 etc., to ir- 



