110 Dr Grant on the Structure and Nature of' Flustr/t. 



the older rows, and cause them to diverge outwards, Pallas 

 imagined (Elench. Zooph. p. 34.) that sometimes the same cell 

 discharges two reproductive gemmules. And as we always ob- 

 serve the first cell of a new row small and deformed, he ima- 

 gined that the two gemmules were discharged at different times, 

 and that the second never arrived at a perfect state. We are 

 still far from being sufficiently acquainted with the intimate 

 structure and economy of animals thus low in the scale, to pre- 

 dict, from the appearance of their dried axis, what may be the 

 real nature^ the mode of growth, or the mode of generation of 

 Flustras ; but it is very obvious, that if the generally received 

 opinion, that they are not compound animals, prove correct, they 

 ought no longer to be placed among zoophytes, whose polypi 

 are always connected together by a com.mon axis, so as to form 

 compound animals, the whole of whose parts are animated by 

 one common principle of life and growth. 



The chief difficulties in examining the living phenomena of 

 Flustrae, and which have probably retarded our knowledge of 

 the structure and economy of these beautiful marine produc- 

 tions, are the extreme minuteness, the shyness, and the compli- 

 cated structure of the polypi ; the quantity of earthy matter in 

 the parietes of the cells, rendering them somewhat opaque; the 

 circumstance of the most common branched species, as the Flus- 

 trajbliacea, F. truncata, &c. having the cells disposed in two 

 opposite planes, which are closely connected to each other, back 

 to back, and which prevents the accurate examination of these 

 branched species under the microscope by transmitted light ; 

 and the circumstance of the sessile species being fixed imniove- 

 ably on the surface of solid bodies, whose opacity likewise pre- 

 vents their minute examination by transmitted light. The nu- 

 merous species of Flustros in the Frith of Forth, and their great 

 abundance, both in deep water and near the shore, present a 

 very favourable opportunity of examining the recent structure, 

 and watching the living phenomena, of these animals at all sea- 

 sons of the year ; and a careful examination of a single species, 

 would not only illustrate the history of this numerous and ob- 

 scure genus, but would likewise throw much light on the equal- 

 ly unknown nature of Cellepores^ Discopores^ Tubulipores, Es- 

 charce, and some other nearly allied calcareous zoophytes. The 



