350 ABSTRACTS OF PAPERS. [VOL. II. 



asters, and those in the enucleated fragments are smaller still 

 and often not demonstrable. 



The observations indicate that the astral rays, whatever be 

 their other functions, are in part an expression of centripetal 

 currents of hyaloplasm (continuous or interalveolar substance), 

 which lead to the formation of the perinuclear hyaloplasmic 

 zone, and of the clear centers of the cytasters--a conclusion 

 essentially in agreement with the early views of Fol. They 

 show further that the asters (centrosomes) must be regarded 

 as centers of cytoplasmic division, though not ordinarily effect- 

 ive unless connected with nuclear material. They seem to 

 leave no doubt, finally, of the formation de novo of functional 

 asters and centrosomes, capable of division, and show that such 

 formation may be entirely independent of the nucleus. 



XVI. METAMORPHOSIS IN THE HERMIT-CRAB. 



M. T. THOMPSON. 



IN Eupagurus longicarpus only the first six larval stages are 

 distinct : the four zoeas, the important glaucothoe, and the 

 first of the adolescent stages. In the zoeas and the early part 

 of the glaucothoe stage, the "livers" or midgut diverticula 

 are cephalic and thoracic. There are two pairs of these ; a 

 pair of Lesser Lobes opening dorsally into the stomach, and 

 a pair of somewhat four-lobed Greater Lobes opening laterally 

 into the stomach. 



During the glaucothoe stage, however, three of the divi- 

 sions of the greater lobes become atrophied. The fourth or 

 posterior division, at about the time of the second or third day 

 in the shell, grows back into the abdomen. But the lobe of 

 the right side of the body crosses under the intestine to the 

 left, so that both lobes lie on the left of the intestine, which 

 is thrown to the right. At this time the bladders of the 

 Green Glands also migrate into the abdomen. Then the append- 

 ages which will be lost become atrophied, and the body mus- 

 culature alters to the adult type. So the glaucothoe, which was 



