312 



The Microscope. 



refringent lense seated in a cup of black or red pigment. The lense 

 arises from the fusion of several refractive globules, and the pigment 

 layer or choroid from the similar coalescence of pigment-granules. 

 The animal, in swimming, always moves the " eye " forwards. — Am. 

 Naturalist. 



Sense-Organs of Sponges. — Von Lendenfeld describes, under 

 the name synocils, some peculiar sense-organs in Grantia, which had 

 previously been described by Stewart as palpocils. From the sur- 

 face pi'oject long conical processes, about 0.1 mm. in length, most 

 numerous near the incurrent pores. These organs consist of pro- 

 longations of the mesodermal intercellular substance, and arc 

 apparently covered with a delicate epithelium. At the base are 

 several oval nuclei, each surrounded with an irregular envelope of 

 protoplasm, which sends out root- like processes, one of which runs 



to the tip of the synocil, (see cut). Von Lendenfeld suggests that 

 the reason why these organs have escaped observation by all who 

 have studied living sponges is that they are ordinarily retracted, and 

 he recalls certain observations which he had previously made on the 

 retracted sense-organs of other sponges. He hints at intei'esting 

 comparisons of these with some of the peculiar sense-organs of the 

 higher Metazoa, but without entering into any detail. — Ajn. Nat- 

 uralist. 



