March 10, 190.5.] 



SCIENCE. 



387 



Experimental Studies of Adaptation and 

 Selective Elimination in Fishes: Francis 

 B. Sumner, College of the City of New 

 York. No abstract. 



Habits and Reactions of Grabs hearing 

 Actinians in their Chelipeds: J. E. Duer- 

 DEN, University of Michigan. 

 Mobius in 1880 first made known the 

 fact that the crab, Melia tessellata Latr., 

 has the remarkable habit of carrying a liv- 

 ing actinian in each claw. The polyps are 

 carried about in front of the crab, held in 

 a kind of defensive attitude, and it is as- 

 sumed that the actinians, by means of their 

 stinging threads, may be useful to the crab 

 for purposes of offense and defense, while 

 the activity of the crab may serve to bring 

 the actinian into the neighborhood of more 

 prey. During a recent visit of the writer 

 to the Hawaiian Islands, under the auspices 

 of the Carnegie Institution, two specimens 

 of Melia, both bearing an actinian in each 

 claw, were collected, and observations made 

 upon their habits and reactions. These 

 may be summarized as follows: 



1. The eommensalism is not restricted to 

 a single species of actinian. One crab car- 

 ried a Bunodeopsis and the other a Sagar- 

 tid. The species are interchangeable, and 

 the crabs will dislodge a small polyp to take 

 up a larger. Apparently the crab is not 

 aware of the presence of an actinian until 

 it comes in actual contact with it ; dislodg- 

 ment of a fixed actinian is brought about 

 by means of the first pair of ambulatory 

 limbs. 



2. When irritated the crab moves its 

 chelipeds so as to place the actinians in 

 such a position as to best serve as a means 

 of defense. Food given the polyps is ab- 

 stracted by the crab by means of its first 

 pair of walking limbs, the stimulus to ac- 

 tivity being probably derived from the 

 diffusion of the meat juices. 



3. Melia has lost the direct use of its 



chelipeds as organs of defense and offense, 

 or for grasping objects other than the ac- 

 tinians; in correlation with this the func- 

 tions of the first ambulatory appendages 

 have become largely modified. 



4. A second species of crab, Polydectus, 

 was also found which bears an actinian, 

 Phellia, in its chelipeds. 



On the Structure of the Larval Oyster and 

 its Occurrence in the Plankton: Joseph 



5. Stafford, McGill University. Read 

 by title. 



A Statistical Study of Correlation and 

 Selection in Lepidoptera: Henry E. 

 Crampton, Barnard College. Read by 

 title. Henry S. Pratt, 



Secretary. 



SCIENTIFIC BOOKS. 

 Vorlesungen ixher Pflanzenphysiologie. Lud- 



wiG JosT. Jena, Gustav Fischei-. 1904. 



Pp. xiii + 695; 172 figures. 



In the form of forty odd lectures the au- 

 thor presents a comprehensive view of the 

 whole field of plant physiology. In the pref- 

 ace he states that it is his purpose to supply, 

 in this volume, a book for the student, which 

 will fill the gap between Pfefler's exhaustive 

 treatise and the short accounts found in va- 

 rious general text-books. In this he has suc- 

 ceeded and has filled a long-felt want for the 

 reader who wishes a full, but not too detailed, 

 account of the important facts and problems 

 of plant physiology. There is a departure 

 from the usual mode of treatment, in that the 

 subject is divided under three main heads, 

 instead of two. The first of these concerns 

 the chemistry and nutrition of the plant and 

 occupies somewhat less than half of the book. 

 The rest is about equally divided between a 

 section entitled ' Formwechsel,' treating of 

 growth and reproduction, and another en- 

 titled ' Energiewechsel,' which has to do with 

 movements of both growth and locomotion. 



In general the treatment of nutrition does 

 not differ materially from that of many other 

 books, except that it is fuller. Under the 

 general term assimilation is considered both 



