46 G. MNDSTRÖM, IIELIOLITIDiE. 



3 3 3 



areas arise, as it seems in a quincunxial arrangemeut 2 2 (see figs. 25, 27), whicli, how- 



ever, soon is disturbed through the enlargement of the polypary with a great numbei' of 

 new calicles. Tabulte have been secreted at an early period, almost immediately after the 

 wall (fig. 28), thus appearing before the septa. 



Gemmation. This is of three different sorts: 1. Coenenchymal, 2. Iniracalieinal, 

 3. Epithecal. 



1. Coenenchymal (pl. i figs. 32, i — iv and fig. 33). The series of sections, representing 

 this change, has been obtained hj scraping down with a knife the little calicle and cau- 

 tiously observing ever}- change. It embraces only a depth of one millim. ere unaltered 

 coenenchyma was reached. Beginning from below (fig. 32, i) some nine coenenchymal 

 tubes are seen to have assumed a deeper colour than the surrounding tubes and a reduc- 

 tion has set in at the lowest riglit corner. Next, as seen in the bottom of section ii, which 

 actually includes two stages, the walls of several tubes have been reduced or absorbed at 

 the right hand while they are still complete on the upper side at left. In sect. ii proper 

 all tubes have vanished and an open area is created. Then the new septa begin to grow 

 out irregularly, of unequal size, being already twelve in section nr. In the last stage figured, 

 sect. IV, they have grown still longer, tending towards the centre of the calicle. The com- 

 pletion of this, other specimens taken in consideration, seems to be, that the ne\v formed 

 septa attaiti the centrum, that a columella is formed by their union, that a new reduction in 

 size sets in and the normal structure of the species is attained. In a longitudinal section 

 representing the coenenchymal gemmation (pl. i f. 33) we also see how the coenenchyma 

 gradually is dissolved, how the tabulce are deranged, how soon a large calicular tabula is 

 formed still interrupted by some irregular, remaining tubular walls, till at last the calicular 

 tube is ready formed with its regular tabula?. 



2. The intvacalicinal gemmation (pl. i figs. 34, i — iv and 35). The notion of its various 

 phases has been obtained in the same way as in the previous case. A regular calicle, at 

 the same level as the surrounding coenenchyma (sect. i) half and half of interstinctus and 

 decipiens type, as so often occurs, with eight short septa on one side, and none on the other 

 begins to raise its margin (sect. ii), which thus becomes osculating and rises more and more 

 above the coenenchyma so as to assume the shape of a little erect tube. In this stage 

 there has been formed all around the septa, which now are distinctly twelve, between 

 them and the theca a zone of coenenchymal tubes. This new theca, which of course 

 did not exist before the calicle began to grow upwavds, has origiuated at the same ti me 

 the rising took place, and in sect. ii we find its presence by the two small tubuli of inci- 

 pient coenenchyma at the lowest, left corner. In the third stage iii the coenenchymal 

 ring has widened and been finished all round with its own strong and well marked theca. 

 There are now two theca?, an interiör one from which the septa start, being the primi- 

 tive calicular theca from which the septa emanate and an exteriör one, enclosing both 

 coenench5'ma and calicle. Tlie calicle and the septa have changcd their aspect during 

 this procedure, the septa are twelve, but irregular, broad, ingoing folds. The newformed 

 coenenchyma is ovidently an outgrowth from the interiör theca, because the walls which divide 

 its tubuli, regularly proreed from tlie angles between the. septa towards the exteriör theca. 



