192 CARNEGIE INSTITUTION OF WASHINGTON. 



While collecting algae, the investigator happened to find another sub- 

 merged aquatic in its blooming period. This was the dioecious plant 

 Thalassia testudinum. Both sexes were collected and the manner of pollina- 

 tion was studied in the Laboratory, as well as the germination of the pollen- 

 grains. Of this latter subject a number of drawings were made. 



The Laboratory closed on July 27, but the author was furnished by the 

 Director with a launch and a man to continue his research about 200 miles 

 north of the Tortugas, on the mainland of Florida, in the vicinity of Miami, 

 as mentioned above. Here, in addition to the taking of transpiration-rate 

 records on the pneumatophore prop-roots of old trees, the writer made an 

 extensive series of hydrometric observations on the waters of the Miami 

 River and Biscayne Bay. These observations were made every half mile, 

 starting out in the Atlantic, crossing the bay, and up the river as far as any 

 mangroves extended, the data bearing on the distribution of Rhizophora in 

 the Florida coast region. The water was taken both at the surface and on 

 the bottom by the use of the deep-sea water-sampling apparatus designed by 

 Dr. A. G. Mayer and used by the late Mr. Drew in his work on the bacterial 

 content of the sea-water of the Florida Key region. The peculiar conditions 

 of the overlapping strata of water near the mouth of the Miami River made 

 these results most interesting. The same sort of observations were also made 

 on Arch Creek, v*^hich hkewise empties into Biscayne Bay. 



Herbarium specimens of a number of noteworthy species and also material 

 of Rhizophora for histologic study on the structure of leaves from plants 

 growing in fresh water and those in salt water were collected in the vicinity 

 of Miami. Live material of the Tillandsias growing on the mangroves as 

 epiphytes was sent north for future study and cultivation in the green- 

 houses, as well as some young Rhizophora plants. On the upward trip, 

 aboard the yacht, notes were taken and maps made of all the keys on which 

 mangroves were lacking from Key West to Miami. As nearly all the Florida 

 Keys support a luxuriant flora of mangroves, these maps note only the excep- 

 tions. The reasons for the lack of Rhizophora at these particular places will 

 be given in a larger paper dealing with this research. 



The author plans to continue the work in a future season, at a tropical 

 laboratory, on the physiology of special cells in the plant's embryonic struc- 

 ture. Such work Avould require more abundant material and more rapid 

 manipulation of the material than the Tortugas station affords. The hope 

 is here expressed that the Institution will soon be supplied with a permanent 

 tropical laboratory, so situated that botanical research similar in char- 

 acter and scope to that done at Buitenzorg, etc., may be pursued in this 

 hemisphere under the Institution's auspices. 



Report on Studies at Tobago, British West Indies, by Hubert Lyman Clark. 



The abundance of echinoderms on the reefs near Pigeon Point, Tobago, 

 made the location of the laboratory there an ideal one for me. My work 

 developed along three lines, each of which gives promise of valuable results. 



The discovery of a crinoid living in shallow water in Buccoo Bay, where 

 it was common and easily accessible, enabled me to study the habits and 

 reactions of a group not hitherto available for such study, for this crinoid, 

 Tropiometra carinata (Lam.), belongs to a family of free-living forms (coma- 

 tulids), so poorly represented at the Murray Islands, Torres Strait, that it 

 was not included in the comatulid studies I made there at the Carnegie 

 laboratory in 1913. I have thus been able to supplement those studies, 

 and the results are of no little interest, Tropiometra carinata being a much 

 hardier species tlian any hitherto observed. This hardiness was shown not 



