lumen. Numerous small vacuoles were seen 

 throughout the tissue of both the fed and the 

 nonfed squids. Thus, a large percentage of the 

 cells of squids from both treatments could be 

 considered to be mature. Additionally, a few 

 medium-sized and large vacuoles were found in 

 the nonfed hatchlings (Fig. lA). 



The greatest differences between feeding- 

 treatments were found in the L. forbesi that had 

 survived for more than 1 week. The digestive- 

 gland tissue of the squids that had been offered 

 zooplankton, and presumably had fed because of 



their longevity, consisted of thin walls with 

 many long, thin lamellae that extended into a 

 very large lumen (Fig. 2A, B). The volume of the 

 lumen was much greater than that of the diges- 

 tive-gland tissue. This tissue was characterized 

 by vacuoles that were few but very large (Fig. 

 2B). Conversely, the digestive glands of the 

 squids that had been raised on DOM had grown 

 but had retained an overall appearance very sim- 

 ilar to that of the hatchlings. Digestive-gland 

 tissue was massive, occupying much more 

 volume than the lumen; furthermore, it was 



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4* 

 6 



Figure 1. — Laboratory-hatched Loligo forbesi, < 1 day 

 old: A, .3.8 mm dorsal mantle length (DML), nonfed; B, 

 3.3 mm DML, from a container with zooplankton food organ- 

 isms present; C. 3.9 mm DML, from a container with zoo- 

 plankton food organisms present. Scale bar = 100 (xm. 



Figure 2. — Laboratory-reared Loligo forbesi, > 1 week 

 old: A, 3.4 mm dorsal mantle length (DML). fed: B, 4.0 

 mm DML, fed; C, 4.2 mm DML, from a container with 

 elevated concentrations of dissolved organic matter. Scale 

 bar = 100 jim. 



997 



