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The Nervous System and Subradular Organ 

 in two Genera of Solenogastres. 



By 



Harold Heath, 



Leland Stanford Jr. University, California. 



With Plate 27. 



Among the material collected by the U. S. F. C. Str. Albatross 

 in the vicinity of the Hawaiian Islands during the spring and summer 

 of 1902 were a small number of Solenogastres that have come into 

 my possession. An additional collection was made while I was acting 

 naturalist aboard the same vessel in Alaska during the past summer. 

 Complete reports on these species will appear in the Bulletin of the 

 Fish Commission ; but permission has kindly been granted me by Com- 

 missioner G. M. Bowers and his staff to publish this preliminary 

 paper on some features connected with the nervous system. 



All the Hawaiian specimens were killed and fixed in 50 °/o alcohol 

 for an hour or so when the percentage was gradually increased to 85. 

 The same method was employed with several specimens of Alaskan 

 species and the results in all cases were highly satisfactory. Contrary 

 to a commonly expressed belief the cuticle covering the body is fairly 

 porous and experiments show that it is by no means impervious to 

 the ordinary fixing solutions. Where alcohol of low grade is used as 

 a killing fluid it is desirable to keep the material at a temperature 

 not exceeding 15 "^ C to prevent maceration ; otherwise no precautions 

 are necessary. 



In this connection it may be of value to give the results of fix- 

 ation with other reagents where the preservation of the spicules and 

 the normal external appearance was not a desideratum. Formaldehyde, 

 corrosive sublimate, corrosive acetic, alcohol of different grades, picro- 

 acetic, Gilson's, Flemming's and Vom Rath's fluids and several other 

 mixtures that proved valueless were used. The first two gave indiffer- 

 ent results at best; corrosive acetic and Gilson's fluid were very good; 



