DEPARTMENT OF MARINE BIOLOGY. 169 



Observations on the Formation of Beach Rock (?) in the Laboratory. 



In the interest of geologists and biologists I am adding a brief note to my 

 report, about the formation of thin sheets of rock-like material in some of 

 my protozoan cultures which were set up with material from Tortugas, Key 

 West, and Miami, Florida. The cultures were set up in quart jars with a 

 considerable quantity of coral sand, algae, and sea-water. After remaining 

 practically undisturbed for about 18 months there was found on the surface 

 of the sand a layer of rock-like material which consisted of coral-sand particles 

 cemented together, apparently with fine calcareous material. Under the 

 microscope the material resembled beach rock very closely. It occurred to 

 me that essentially similar processes might account for the formation of the 

 rock in the jars and of natural beach rock, and I therefore turned over the 

 cultures with data to Professor Richard Field, of the Department of Geology, 

 Princeton University, who kindly agreed to examine the material. 



A Botanical Reconnaissance of Tahiti in the Summer of 1922, hyW. A. Setchell. 

 Progress has been made in working over the collections and towards 

 drawing up reports. Various of the Spermatophytes have been submitted 

 to E. D. Merrill (Manila), I. Burkill (Singapore), A. S. Hitchcock (Washing- 

 ton), R. Schlechter (Berlin-Dahlem), and Paul Standley (Washington), 

 who have furnished identifications, notes, etc. A list, with notes, is in 

 process. The Pteridophytes have all been submitted to W. R. Maxon (Wash- 

 ington), who has his report practically completed. The mosses are in the 

 hands of V. K, Brotherus (Helsingfors), who will report soon. W. R. Pearson 

 (Manchester), to whom the Hepaticse were sent, died before he had proceeded 

 very far and this collection is at present among his effects. The Fungi are 

 ready but have not been sent to any specialist. E. A. Vainio (Helsingfors) 

 has submitted his report on the Lichens and it will go to press very soon. 

 Reports on the soils (C. B. Lipman, Berkeley), the rock samples (G. D. 

 Louderback, Berkeley), and the corals (T. Wayland Vaughan and J. Edward 

 Hofmeister) are under way or have been made in preliminary fashion. The 

 preparation of the report on the general aspects of the vegetation and on the 

 algse, particularly of the reefs, is now in advanced condition. 



Investigations on the Hybridization of Echinoids conducted at the Misaki 

 Marine Biological Station of Tokyo Imperial University, from April 24 

 to August 16, 1923, by D. H. Tennent. 



During these investigations, material for the study of the morphology of 

 the chromosomal groups of 9 echinoids was obtained. This includes series 

 of eggs from 7 straight fertilizations and from 11 cross-activations. Of the 

 latter, 8 are from 4 reciprocal crosses and 3 are from cross-activations made 

 in one direction only. Methods were devised which enabled me to obtain 

 above 95 per cent activation in every cross made. 



The success of the investigations lies in the application of observations 

 on the processes of straight fertilization in the species whose spermatozoa 

 were used as foreign spermatozoa. The investigations have established 

 clearly the fact that the processes of fertilization differ in different species 

 of echinoids. In some, e. g., Temnopleurus toreumaticus, the cortical reac- 

 tion is striking and a widely separated fertilization membrane is formed. 

 On the other hand, the egg of Ileliocidaris tuberculata never forms a widely 

 separated fertilization membrane, the thick membrane which is formed 

 after activation appearing slowly and investing the egg rather closely. 



