90 



In the siiiallei' buds, wliicli were generated principally in tlie 

 marginal regions of tlie nnder surface the development of tlie skeleton 

 can easily be traced, as the bnd.s differ very much in age. They are 

 of a n)uch more regular structure tlian the larger ones. 



In the youngest buds, with a diameter of about 0.5 mm., nothing 

 of the skeleton is visible except the theca, which appears as a thin 

 wall, stretching obliquely u[)ward and consequently looks like a 

 truncated cone. (Textfig. (i). 



Fig. a. X 45. 



Fig. /.. X 45. 



Fig. c. X 4B. 



The theca has no perforations, which come forth only in much 

 older buds. Soon after this the first cycle of six septa spring up. 

 They |)roceed from the theca further towards the centre of the bud. 

 (Textfig. b). The u|)per rim of the theca rises above the septa. The 

 columella also develops in this phase as short projections in the 

 basal parts of the bud. In buds of this size there are never more 

 than six se|ita. They originate almost simultaneously, buds with a 

 smaller number of septa occurring only very seldom. The number 

 of similar buds with less than six septa is too small to ascertain 

 whether the septa arise in a definite order. 



The next cycle of septa can only be observed in buds of about 

 1 m.m. in diameter. In ihem the septa of the first cycle have 

 already considerably increased in size and in thickness, and are 

 already provided with some dentations. (Textfig. c). Likewise the 

 columella has grown larger in this stage. The septa of the second 

 cycle are distinguishable at first sight from those of the first cycle 

 by their being less developed and being shorter. The bud has now 

 attained the length of the youngest stage described by Bourne'), 



1) G. C. Bourne, On the Posterabryonic Development of Fungia. Transact. Roy. 

 Dublin Soc. Vol. V, 1893. 



