76 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



METHODS. 



Most of- the material eggs, larvee, and adults was fixed in a saturated solution of corrosive 

 sublimate, to which had been added 2 per cent of glacial acetic acid. A fresh solution was made 

 as soon as the tine white precipitate appeared, which is usually present in old solutions. This 

 fibrins- aerent Brave very erood results. Material tixed in Perenyi's fluid was found more valuable 

 in some few respects than the acetic sublimate. When segmentation stages were treated with a 

 5 per cent solution of formaldehyde, the blastomeres stood out almost as distinctly as in the 

 living material. The larger species of the two Actinotrocha found in Beaufort Harbor is much 

 more active than the other, and when it comes in contact with the fixing fluid the preoral lobe is 

 bent upward into an unusual position. Consequently a few drops of 4 per cent solution of 

 muriate of cocaine in 50 per cent alcohol was added to the water containing the Actinotrochse. 

 After this treatment they died in their usual form when put in the fixing fluid. 



Flemming's fluid, as well as the acetic sublimate, was found to be a very valuable fixing 

 agent for the Actmotroch.se. Heidenhain's iron hematoxylin was used in staining sections of the 

 adult, and a secondary stain of alcoholic eosin or rubin gave very good results. The most satis- 

 factory stain for sections of young larvse and Actinotrocha was found to be a solution of safranin 

 in anilin water. Since it was very desirable to make a study of the adults throughout the year, 

 and as it was not possible to remain in Beaufort for this purpose during the winter and spring 

 months, specimens were collected and sent to Johns Hopkins University at different times. 

 Here they were placed in aquaria filled with sea water, which was kept in good condition by 

 a rich growth of diatoms on top of a layer of sand. Not only did the diatoms keep the water 

 from becoming polluted, but they also afforded abundant food for the Phoronis, so that healthy 

 individuals with their lophophoral tentacles fully expanded were continually at hand for a live 

 study. The authors are much indebted to Dr. Caswell Grave, the originator of the diatom method 

 in rearing Echinoo\ rm larvse, for the use of his aquaria. Drew's modification of Patton's method 

 for embedding and orienting eggs was used with fairly good success, although a large percentage 

 of the embryos were broken during the process. Most of the embryos were cut into sections 3 

 p. thick, but for some purposes sections 2 // thick were used. 



BREEDING HABITS. 



Andrews's (1) observations on Phoronis architecta bring him to the conclusion that either the 

 sexes are separate in that species or that if the individuals are hermaphroditic the male and 

 female elements mature at different times. Many specimens examined by us during May, June, 

 July, August, September, and October, both by means of sections and when alive, showed in no 

 ease ovaries and testes occurring at the same time in an individual, but ovaries and testes 

 undoubtedly occur together in the same individual in /'. australis. Benham (2) has observed 

 this, as we have also, in material sent to us by Mr. Ikeda. 



During the month of January the peritoneal tissues surrounding the blood ereea is very 

 abundant, but as a rule at this time no eggs or spermatozoa are found in it. In one individual 

 out of some 20 or 30 a few ovarian eggs were found, however. All of these specimens 

 collected in January were without lophophoral organs, and we kept many of them in aquaria until 

 the 1st of May. At this time lophophoral organs began to make their appearance in some, 

 while in others thev were absent. In all the specimens, however, either ovaries or testes were 

 present, as was also the case in specimens collected at Beaufort in the early part of May. 

 Further reference will be made to the lophophoral organs and their relation to the breeding 

 season under the section which deals with the structure of the adult. 



The breeding season of Phoronis archik eta extends from March or April to November or 

 December. Ikeda (9) has stated that "the breeding season of Phoronis ijimai ranges through 

 about half of the year, say from November to June or July." There seems to be a surprising 

 difference in the time of breeding between these two species. The Actinotrocha at Beaufort are 

 found throughout the summer and autumn, but they arc especially abundant during August and 

 September. Ikeda has suggested that Phoronis annually " changes its generation." It does not 



