152 ZOOPHYTES. 



Numerous simple and compound vesicles are crowded together on the 

 branches of the Sertularia abietina. The former are ovoidal, like those of 

 certain other Sertulariae.— Plate XXIV. fig. 19; XXV. fig. 1. The 

 latter consist of a hollow spherule, with an elevated vertex, sustained on a 

 ventricose pedestal, considerably smaller, this pedestal bearing some resem- 

 blance to the ovoids. Eight or ten such compound vesicles, close in a 

 row, may be compared to apples on the branch of a prolific tree. — 

 Plate XXV. figs. 2, 3 ; Plate XXIV. fig. 3. 



The same specimen sometimes bears both the simple and the com- 

 pound vesicles. 



Each kind of vesicle contains a single, vivid yellow corpusculum, in 

 as far as I have been able to ascertain. 



To determine the nature of the corpusculum, two branches,.each with 

 numerous compound vesicles, were suspended in a tall glass cylinder on 

 the 1st of May. Eighteen planulae could be enumerated at the bottom 

 on the 10th of that month. These seemed nearly half a line long, round, 

 one extremity obtuse, the rest tapering almost to a point, the surface 

 smooth and uniform, of a beautiful vivid yellow colour. Altogether, this 

 subject resembled a minute pear. — Plate XXIV. fig. 4, a, b, c : enlarged, 



A, B, C. 



Some were observed on the side of the vessel. Their peculiar shape 

 and evident solidity seemed unfavourable to ascent. 



Another portion of the same Sertularia had been consigned to a ves- 

 sel wide and shallow, so as to be accessible to the microscope — always a 

 necessary precaution when intermeddling with diminutive objects. Here 

 two or three similar planulse appeared also, on the 10th of May, and on 

 the 12th other two or three. Small yellow spots were seen besides. On 

 May 13, three nascent Sertulariae, all yellow, could be recognised ; one 

 rising as the prominence of a flattened spherule ; a short spine issued from 

 another : and from the third spot a spinous prolongation shot up about two 

 lines, with the summit slightly enlarged. Towards next evening this en- 

 largement was forking ofi" nearly at right angles to the prolongation now 

 seen to be a stem, which rose still higher, and it was evidently acquiring 

 the figure of a cell. At this time the summit of the stem was likewise 



