SPONGILLA. 153 



crowded in one place, while they are entirely wanting in another." 

 They are about the size of turnip-seed, of a globular shape 

 and yellowish colour, with a rough external surface, but which 

 is not ciliated, neither have they any power of locomotion.* 

 They are composed P. of contained globules essentially similar 

 to the gelatinous granules already described ; and 2°. of an elastic 

 cartilaginous envelope which, according to M. Gervais, consists 

 of two layers, — an inner one, which is firm and reddish, and an 

 outer one, which is tomentose and tinted with a gilded yellow. 

 There may be observed on most of the sphgerulas, a spot to 

 which attention was first called by Link and Raspail. They 

 considered it to be a hihcm, but Gervais is of opinion that it 

 cannot be so, because the sphaerula has no pedicle or funiculum, 

 lying loose amidst the green globules, and because this pre- 

 tended hilum is sometimes multiplicate, viz. it is sometimes 

 double, and still oftener triple or quadruple. The spot in ques- 

 tion has usually the reddish colour of the inner envelope, for it 

 is in fact formed by a portion of this becoming visible in con- 

 sequence of the partial obliteration of the external tunic. It is 

 at this spot that the contained globules burst through, and after 

 they have escaped, there remains a very perceptible hole. While 

 still enclosed in the sphaerula the globules lie sometimes scat- 

 tered confusedly in the interior, but occasionally they are united 

 in little it)undish masses without any peculiar envelope. In some 



* " Autumnali tempore in luijus poris sparsis glohulos caerulescentes 

 magnitudine seminum tliymi, nitidos in flainma candelre fulgiirantes ob- 



servavit C. Blom. M. D. an corpora peregrina ?" Lin. Syst. 1299. In 



a letter to Ellis, Limiffiiis thus describes the same bodies: — " Tbere is 

 lately come to my hands, from one of our Swecdish lakes, a most beau- 

 tiful Spongia, though in a dried state, in which I can distinctly see some 

 animalcula in their transparent vesicles. The branches of this Spongia, 

 when brought to the flame of a candle, take fire with a bright effulgence, 

 and the animalcules explode in little fiery globules of a very lively blue." 

 Lin. Corresp. i. p. 183. 



