104 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. X, NO. 4. 



in P. a/rchitecta they are used in building the tubes. II. B. Torrey (22) has made the interest- 

 ing-observation that in some specimens of P. pacifica the lophophoral organs are like those in 

 P. australis, while in others they are like those in /'. architecta. It is probable that in part of 

 the specimens which Torrey examined the lophophoral organs were not full grown, while in the 

 rest they had reached their full development. 



Our observations indicate that Andrews" supposition concerning the tube-building function 

 of the lophophoral organs can not be held. Individuals without the lophophoral organs 

 build new tubes covered with sand grains just as do those with the organs, and young specimens 

 of Phoronis architecta, which are in possession of tubes, never have lophophoral organs. These 

 two facts prove quite conclusively that the lophophoral organs of Phoronis architecta are not 

 used for tube building. 



Masterman's view that the lophophoral organs of P. buskii are glandular, and that they fur- 

 nish mucus to hold the eggs and embryos in masses can not be applied to P. architecta, for in 

 this species the eggs and embryos are not held in masses. 



Specimens ai Phoronis architecta have been examined during almost every month in the year 

 in order to discover whether or not there is any relation between the lophophoral organs and the 

 breeding season During the months of dune, July. August, September, and October examina- 

 tion of many specimens of Phoronis architecta shows that more than one-half are with lopho- 

 phoral organs — i. e., with the "carpel-like organs" and the "'spherical sense lobes" (Andrews). 

 Examination of specimens taken during these months shows that some contain ovaries and eggs 

 while others do not, and that all contain spermatozoa in the body cavity, but that only those 

 without ovaries contain testes. Occasionally an egg floating freely in the body cavity is found 

 in specimens with testes. These facts are correlated with the presence or the absence of the 

 lophophoral organs, for these organs are present in specimens with testes and without ovaries 

 and absent in specimens with ovaries and without testes. 



During the latter part of December and the tirst part of January specimens of J', architecta, 

 some of which were collected in Beaufort Harbor at that time and some of which had been kept 

 alive in the laboratory of Johns Hopkins University since the summer months were examined. 



Many of these specimens (Ho or 40) were examined by crushing the posterior end and also 

 by cutting sections, but with one exception all of these individuals were found to be without 

 ovaries and testes. In the case of the exception, a few ovarian eggs were present, but the ovaries 

 were still very young. The blood ca*ca at this time are surrounded by a great abundance of the 

 peculiar peritoneal tissue, which later gives rise to the reproductive organs. Lophophoral organs 

 were absent both in specimens collected at Beaufort during the first part of January and in speci- 

 mens collected during the summer and kept in the laboratory. 



During the months of February, March, and April the specimens in the aquaria at Johns 

 Hopkins University were examined quite frequently, but until March or April there was no sign 

 of lophophoral organs. Then they began gradually to develop in some specimens until by the 

 first of May they were full size. At this time another lot of live material was received from 

 Beaufort which afforded some very interesting observations. The number of individuals with 

 and without lophophoral organs were in about the same ratio as during the summer months. 

 At this time, in specimens with lophophoral organs, the testes are 'present but the ovaries are 

 not, while specimens without lophophoral organs possess ovaries and contain ovarian eggs. 

 Quite of ten specimens with lophophoral organs have large bunches of spermatozoa floating freely 

 in the body cavity, and in some cases these occur inside the nephridia. In one individual a large 

 bunch of spermatozoa was found lodged in the end of the lophophoral organ's pocket-like 

 cavity. 



Judging from our observations, it seems that the relation of the lophophoral organs to the 

 breeding season is as follows: Some adults are giving rise to eggs throughout the months of 

 May, June, July. August, September, and October. None of the individuals arising from 

 these eggs become sexually mature until March or April of the next year. Those which are 

 the oldest — i. e., those born in the early months of the year before — develop testes and lopho- 

 phoral organs in March or April. Then they lose their lophophoral organs, the testes disap- 



