I46 REPORTS ON INVESTIGATIONS AND PROJECTS. 



the noddies can pass the whole night in the water and still arise from it in the 

 morning. The sooties, on the contrary, perish in nearly every case if forced 

 to remain long in the water. If, however, small wooden floats are left in 

 the water, the sooties immediately utilize them and can spend the whole night 

 under such conditions, and be little the worse for the experience on the fol- 

 lowing morning. 



It follows from these experiments that the sooties can not be expected to 

 return over water from a distance greater than that which can be covered in 

 a day's flight. If the bird were lucky enough to meet with driftwood at the 

 proper time it would doubtless survive. The noddies are not so limited in 

 their water capacities. We yet have hopes of getting returns from Galves- 

 ton and Mobile with them. 



Report of Prof. Dr. B. Jorgensen, of the Cathedral School of Bergen, 



Norway. 



My visit to the marine laboratory at the Tortugas occupied three weeks 

 and a half, during which time I was engaged in a life-study of the Peridinea. 



As the laboratory is somewhat near the Gulf Stream, a thorough exam- 

 ination of the plankton there should be of more than usual importance, for it 

 would give one the opportunity to compare the Gulf Stream plankton with 

 that of the seas of northern Europe. On the whole, the plankton of the 

 Tortugas is rather rich, considering its subtropical situation and the well- 

 known fact that the plankton of the tropical and subtropical regions is often 

 very poor as to quantity. Some of the groups of the Peridinea were well 

 represented, while others occurred only sparingly. There were only few 

 Ceratia, so that the material was scarcely sufficient for the decision of sev- 

 eral important questions ; for instance, the manner in which active motion of 

 these forms is produced. It is well known that the Ceratia are highly differ- 

 entiated drifting organisms; their often strikingly "luxuriant" and remark- 

 able forms are produced (as a more thorough examination will show) by 

 more or less perfect adaptations to their life as passively drifting organisms. 



The more perfect this adaptation the more closely will the cell be confined 

 to the particle of water in which it is living; therefore it should a priori 

 seem probable that the forms provided with floating apparatus and on the 

 whole best adapted to drifting in the water should be those least capable of 

 active motions. This should especially be true concerning the power of 

 rotation, which in highly specialized floating forms may be expected to be 

 greatly reduced. According to my experience, from the small amount of 

 material obtained at the Tortugas, the Ceratia really seems, from a state of 

 active movability in the lower forms, to have developed to a passive drifting 

 in the higher, and this to such a degree that I was not able to make out any 

 active power of motion by the long-horned forms. It should, however, be 

 stated that the Peridinea are usually very difficult to keep alive and do not 

 well endure being placed on an object-glass for direct study under the micro- 

 scope. It would therefore be rather rash to declare that the specialized 

 floating forms of Ceratia have really lost all their power of active motion, 

 yet it would seem safe to conclude that the long-horned species have lost 

 more or less completely their power of rotation, especially such forms as 

 C. trichoceros and C. tenne. 



Several species of the genus Peridininm were studied. This genus is a 

 difficult one and includes a great many species, very few of which have as 

 yet been defined with sufficient accuracy. 



