DEPARTMENT OF MARINE BIOLOGY. 171 



Comparative Zoology at Harvard, already probably the richest gather- 

 ing of specimens of echinoderms in the world. Dr. Clark's report may 

 be awaited with enhanced interest, due to the 100 or more admirably 

 colored drawings of Murray Island echinoderms made from life by 

 Mr. E. M. Grosse and now being lithographed by him in Sydney. 

 Dr. Clark also spent much time in observing the movements and reac- 

 tions to light of the crinoids, but details of these and other matters 

 pertaining to his work will appear in his prehminary report presented 

 on a following page. 



While at the Murray Islands, Dr. E. Newton Harvey, of Princeton 

 University, discovered a large holothurian, Stycopus ananas, or 

 "prickly fish" of the beche de mer industry. The intestines and 

 gonads of this animal are provided with a red pigment which changes 

 to carroty-red in acids and to purple in alkalis, these changes being 

 reversible. The presence of this natural indicator gave Dr. Harvey 

 a unique opportunity to study the rate of penetration of 26 different 

 acids, and he found that Hving cells resist the entrance of all acids with 

 the exception of salicylic, benzoic, and possibly valeric, but this resis- 

 tance is slight compared with that for alkalis. There is no relation 

 between rate of penetration and degree of dissociation, nor between 

 degree of dissociation and toxicity, but there is a fair coordination 

 between penetrability and toxicity, the most toxic being the ones which 

 penetrate most rapidly. Also, with acids as with alkalis, if the acid 

 is soluble in fatty substances, it usually penetrates rapidly, but if 

 insoluble or only shghtly soluble in lipoids, it can enter the cell only 

 slowly, if at all. Details appear in Dr. Harvey's preliminary account 

 published herewith, and his full report is now in press and is to appear 

 in Traube's "Internationale Zeitschrift fiir Phj^sikalische-Chemische 

 Biologie." 



Mr. Frank A. Potts, Fellow of Trinity Hall, Cambridge, and Balfour 

 Student of the University of Cambridge, carried out an interesting 

 series of observations, discovering the male of the so-called gall-forming 

 crab Hapalocarcinus, the female alone of which forms capsules among 

 the branches of the coral Pocillopora, causing the branches to enlarge 

 by the effect of the water-currents from its gills until it becomes 

 imprisoned in a chamber formed by the coral. The minute, free- 

 swimming male probably enters the capsule only when the female 

 molts. 



The life-history of a curious parasitic cirriped, Thylacoplethus, 

 which infests the snapping shrimps, Alpheus, that live among the arms 

 of crinoids, also engaged the attention of Mr. Potts; and he observed 

 that the male of the hermit crab Pagurus deformis has inherited a single 

 sexual character belonging to the female, having, in addition to its male 

 genital apertures, a pair which are without ducts but are homologous 

 in position with those of the female. 



