SERTULARIA. 137 



taceous stem, tending to lapidescence, with rows of cells but without ova- 

 rian vesicles. 



Endeavouring to reform the Systema, later naturalists have greatly 

 restricted the genus Sertularia, by mutilating it of many important mem- 

 bers. Of these they have constituted various new genera, not always suc- 

 cessfully, and sometimes under rather capricious denominations, as well as 

 founded on characters too vague and indefinite. Likewise the living sub- 

 jects having been seldom studied, or even beheld in them, while the skele- 

 ton was not rare, has perhaps led more readily to the assumption of re- 

 cently dead, and especially of dried specimens, as a guide for systematic 

 aiTangement. 



Thus the inorganic parts are the basis of definition, — in the structure 

 of the stem, distribution of the branches, the shape, position, and number 

 of the cells ; while the figure and the properties of their fugitive tenants 

 remain totally unknown. Such must have been the obvious consequence 

 of the method pursued. Many may have found it difficult to do otherwise. 



A modem author, however, Dr George Johnston, in a comprehensive 

 and excellent work on the subject, has gone far to rectify this defect, by 

 arranging the zoophytes with due attention to the nature of the animals 

 belonging to them. That author is entitled to the greater merit from the 

 labour and diflficulty of accomplishing such a task, for it has exacted equal 

 skill and industry. 



Naturalists attempting to extend and improve the general Systema, 

 have been often unjustly and harshly blamed for apparent confusion and 

 defective precision, — faults not their own, but originating with those 

 writers whose works they were compelled to follow for want of better. 

 Had figures always accompanied descriptions, how much would it not have 

 promoted truth — ^how many complaints, and what grievous annoyances 

 would it not have prevented 



Having disposed of the Tubularia, and by some examples deduced 

 from the nature of the hydra, having spoke of the process of increment, 

 whereby zoophytes are enlarged, we shall resume an examination of seve- 

 ral other subjects. But, always recollecting that as these are only a col- 

 VOL. I. s 



