302 EMBRYONIC VISION, 



pear strong reasons in favour of the former conclusion. 

 Whether the intermediate cavities containing granules, 

 be auditory organs, or rudimentary tentacles, I can- 

 not determine. It is interesting to see in this case, as 

 well as in that of the Feather Plumularia, before de- 

 scribed, the presence of eyes in the free roving Medu- 

 soid, while they are absent in the fixed and stationary 

 Polype. Where these organs are of service, they are 

 provided ; where they would be useless, they are not 

 only denied, but obliterated. The very same phe- 

 nomena are presented by the tubicolous, and therefore 

 stationary, Rotifera, as Steplianoceros, Floscularia, 

 &c., which are sightless when adult, but have two 

 brilliant ruby-like visual specks in the active and 

 swimming young. How beautifully such disci'imina- 

 tions show the minute, individualising care exercised 

 by the Only Wise God in creation! 



From the lateral aspect of the globe, carefully de- 

 picted at Fig. 3, I infer that the substance of which 

 it is composed varies in thickness in diiferent parts ; 

 being thickest at the top, and thinnest towards the 

 marginal canal. From the centre of the roof, hangs 

 down freely within the cavity an organ of granular 

 flesh, somewhat trumpet-shaped and four-sided, its 

 free extremity forming four thickened lips, capable of 

 much alteration of form, and apparently very sensi- 

 tive. From its base diverge four canals, passing ap- 

 parently along the interior of the globe, and joining 

 the marginal canal at the four points where the bulbs 

 of the filaments originate. These four canals are 

 permeated by a circulating colourless fluid ; for at a 

 point about midway in their course, where each en- 



