6 T. KOMAI : STUDIES ON TWO ABERRANT CTENOPHORES. 



the }'ears 19 16-19 19. The\' were observed alive or as fixed and sectioned 

 preparations. Owing to the extremely delicate texture of the body, it 

 is a rather difficult matter to secure good results in killing and fixing 

 Coeloplana. Of various fixing reagents tried for the purpose, Flemming's 

 strong solution was found to be the best suited. A reagent consisting 

 of 100 parts of saturated aqueous solution of corrosive sublimate and of 

 3 parts of glacial acetic acid or 10 parts of formalin gave also fairly good 

 results, but the object must not be allowed to remain too long in it. 

 Double imbedding in paraffin and celloidin after Samassa's prescription 

 ('92) has proved to be the most reliable method for sectioning with 

 histological purpose. But tolerably good results may be obtained by the 

 simple paraffin method too, and for anatomical purpose this method was 

 quite sufficient. For the staining of the material fixed with Flemming's 

 solution, iron-haematoxylin and safranin have proved to be the best, while 

 for the corrosive-sublimate material I have employed with preference 

 Delafield's haematoxylin combined with eosin. Narcotization of the 

 animal always led to discouraging results, since the tissues are very apt 

 to become distintegrated thereby. 



External Features and Life-habits. 



Coeloplana is represented in the waters of Misaki by three distinct 

 species, viz. C. willeyi Abbott, C. mitstikiirii Abbott, and C. bocki 

 KoMAi. All the three species are found in the littoral, C. willeyi and 

 C. mitsukurii on various sea-weeds, but most commonly on certain 

 species of Sargasstcm, and C bocki on stocks of an alcyonacean of the 

 genus Dendrojiephthya. All the species are rather common and may be 

 collected without difficulty. Examples of C. zvilleyi and C inits7ikurii 

 may be obtained by searching carefully among the sea-weeds at all 

 seasons of the year, but the winter is, in my experience, the most 

 favourable time for collecting the material in plentiful supply. The 

 frequency of their occurrence seems to be subject to considerable lluctua- 

 tions in different years and .seasons. In 191 6 I found C. willeyi to be 

 very common especially from Januar)' to April, when a day's search 

 yielded fifty or more individuals of it without much difficulty, while in 

 the summer of the same year, ten individuals of the same were about 

 the utmost that could be collected in a day. C. mitsukurii, which may 

 be found on the same frond of sea-weed together with C zvilleyi, is of 

 a rarer occurrence. This was particularly the case with during those 



