1882.] of the Perivisceral Fluid of the Sea- Urchin. 



371 



and a clear fluid passes through. This gives no coagulum on dilution, 

 but the corpuscles, if removed from the filter and suspended in a 

 saturated solution of sulphate of magnesia, exude abundance of the 

 coagulable material on the addition of water. This is not unlike the 

 results obtained by Mr. Wooldridge in the Leipzig Laboratory with 

 white corpuscles from the lymphatic glands and from the blood of 

 mammals.* 



I have spoken throughout of the substance, upon the formation or 

 exudation of which from the corpuscles the clotting of the Echinus 

 fluid seems to depend, as coagulable material, and not as fibrine. It 

 does not, in fact, either in its chemical reactions or in its microscopic 

 characters, bear any sort of resemblance to the fibrine of vertebrate 

 blood, but appears to be more nearly allied to mucin, although the pos- 

 session by it of the remarkable property of spontaneously shrinking 

 after its first formation gives it a deceptive similarity to fibrine. 



The detailed account of the above investigation will be published in 

 the " Journal of Physiology."f 



III. " Preliminary Note on the Structure, Development, and 

 - Affinities of Phoronis." By W. H. Caldwell, B.A., Cains 

 College, Cambridge, Demonstrator of Zoology. Communi- 

 cated by Dr. M. Foster, Sec. R.S. Received November 

 24, 1882. 



Owing to the time that must necessarily elapse during the prepara- 

 tion of plates, it has seemed to me advisable to publish the following 

 preliminary account of my observations on the anatomy and develop- 

 ment of Phoronis. These studies were made for the most part in the 

 Zoological Station at Naples. I am much indebted to Dr. Anton 

 Dohrn for his great kindness and assistance. I have not thought 

 it necessary in this preliminary note to refer at any length to the 

 observations of previous investigators, % and the bearing of the facts 

 on recent morphological speculation has at most been indicated in 

 the briefest possible manner. I would, however, specially refer to 

 some observations on the development made in the summer of 1881, 

 by Dr. Hatschek, who most generously not only sent me material, but 

 on his return to Naples resigned his work and drawings to me. 



* " Proc. Roy. Soc," vol. 32, p. 413 ; and " Archiv. f. (Anat. u.) Physiol.," 1881. 



f The opportunity for carrying on these observations was afforded me at the 

 Scottish Zoological Station of Professor J. Cossar Ewart and Mr. Gr. J. Romanes. 



X J- Miiller, Wagener, Krohn, Gregenbaur, Schneider, Kowalewsky, Metschmkow, 

 Claparede, Wright, Dyster, Van Beneden, Mcintosh, Wilson, &c. 



