lo6 BRITISH SPONGES: 



sponge, and the oscules and cells or pores formed by the inter- 

 lacing and crossing of the young fibres with the sharp and pro- 

 minent spicula. As a few of these bodies, after several days, 

 did not germinate, I squeezed them sufficiently hard, so as to 

 break their envelopes or shells, and pressed out a little of the 

 inner opake substance, which then very readily grew and en- 

 larged." * 



The various opinions entertained by naturalists relative to the 

 nature of Spongilla have been already mentioned.f Mr Hogg 

 is the latest and most strenuous advocate of its vegetability. 

 From numerous observations and experiments, made with care 

 and under favourable circumstances, he found that the intensity 

 of the greenness of the Spongilla depends upon its more or less 

 direct exposure to the light, for specimens were alternately 

 blanched and greened by turning dowTi the surface of the stone 

 on which they grew, and, after a due season, reversing its posi- 

 tion.:}: Now, as light has exactly the same effect on plants, and 

 is not known to have any similar influence on the colour of ani- 

 mals, the experiments afford a strong presumption that this pro- 

 duction is more nearly allied to the algae or fungi than to any 

 member of the animal kingdom, and Mr Hogg strengthened 

 this inference by other facts. He fomid, for example, that the 



* See some recent observations by Laurent on tbe I'eproductive or- 

 gans of Spongilla in the Microscopic Journal, i. p. 78. 



f In addition to those names of naturalists who advocated the vege- 

 table nature of sponges, especially of the Spongilla, those of Bhimenbach 

 (Elem. Nat. Hist. Trans, p. 271), and De La Pylaye should be added. 

 The latter confounded the Cristatellaj with Spongilla. Bidl. des Sci- 

 ences Nat. xvii. p. 99. 



I Lamouroux ascribed the variable colour of the Spongilla to the na- 

 ture of the sites from which it grew : Bory St Vincent to the presence 

 of the Anabaina impalpabilis. " S' introduit dans I'Eponge d'eau douce, 

 et lui donne dans certains endroits cette couleur verte, qu'elle n'a point 

 quand I'Anabaine ne croit pas dans son voisinage." Ency. Method. Zoo- 

 logie- For this reference I am indebted to my friend, William Thompson, 

 Esq. 



