92 



A. OKA. 



sive sublimate or a weak «olation (0.1%) of cliromic acid, previous to 

 hardening. For staining-, borax-carmin and picro-carmin were chiefly 

 used. In cutting sections, I imbedded sometimes a whole colony, 

 sometimes separate polypides, in celloidin and paraffin. 



In studying the development of the polypide within the stato- 

 blast, I proceeded in the following way. First, a statoblast was put 

 into alcohol to harden its contents which in tlie fresh state consist 

 of a thick milky fluid. Then it was held between two pieces of elder 

 pith, and the edge was cut with a sharp razor so as to make an open- 

 ing in the chitinous shell. Next, it was stained and kept in alcohol 

 until it was to be cut. In cutting tlie statoblast, celloidin v/as in- 

 dispensable, for, the shell being too hard, it was impossible to get 

 good sections with paraffin only. 



For examining fresh specimens, the only thing I had to do was 

 to put a colony (stupefied with Cocain) or a part of it on a slide,' and 

 cover it, putting a wire ring under the cover-glass to prevent over- 

 pressure. In this condition, the polypides had no power to retract, 

 and the ciliae were in vi^'orous motion. 



To study their habits, I kept colonies alive in a glass vessel. I 

 kept also the statoblast in a vessel, in which a contrivance was made 

 to have water always flowing. At last the shells burst, and the little 

 polypides peeped out of the sutures, carrying about the shells like a 

 tiny bivalve. Each of them floats about for a very short time, and 

 then attaches itself by means of the gelatinous ectocyst to any object 

 it may meet with, and gives rise to a new colony. 



A. Anatomy. 



The branched membranaceous tube (cœnœcial endocyst) forming 

 the greater part of the mass of a colony, together with the gelatinous 

 covering (ectocyst) over it, constitutes the cœnœcium. The terminal 



