Zoology 139 



When starved Cassiopea loses weight according to the formula y=w (1 a~)x 

 where y is the weight at the end of x days, w is the weight when starving begins, 

 and a is a fractional constant. Thus the loss in weight always remains propor- 

 tional to the body-weight of the animal. 



Dr. A. J. Goldfarb shows that in Cassiopea the maximum rate of regeneration 

 is attained in diluted sea-water containing about 90 parts of sea-water to 10 parts 

 of distilled water. Regeneration is normal again in about 85 per cent sea-water and 

 declines in rate on further dilution. In concentrations of sea-water over and above 

 normal, the rate of regeneration declines rapidly. Thus in Cassiopea, Eudendriutn, 

 and Tubularia the rate of regeneration is most rapid in diluted sea-water. 



Dr. Goldfarb shows that the marine annelid Amphinoma can regenerate without 

 the contact of or stimulation from the central nerve cord. 



By treating the recently fertilized eggs of echini with sodium chloride in sea- 

 water, Dr. Goldfarb succeeded in producing large numbers of fused larvae. He 

 made a detailed study of the causes of these fusions and the various fates of the 

 fused larvae, and the causes of their form equilibrium. 



Dr. J. F. McClendon shows experimentally that the permeability of eggs to ions 

 increases upon being fertilized. 



Dr. E. Newton Harvey found that, as in the case of fresh-water organisms, the 

 tissues of marine animals are penetrated more rapidly by weakly dissociated than 

 by strongly dissociated alkalies. 



Dr. Merkel H. Jacobs shows that there are remarkable differences in the resist- 

 ance of the four common internal parasites of Diadema, and thus the similar habit 

 of life in these four forms is not due to physiological similarity except in certain 

 adaptive characters which are a sine qua non for life within the same host, such as 

 ability to resist the digestive juices. Thus physiological characters of an organism 

 are not merely the result of its environment, but may be as fundamental and char- 

 acteristic as its morphological ones. 



Professor Ulric Dahlgren finds that the electric tissues of Gymnarchus are de- 

 veloped by the differentiation of certain portions of its striated muscle-tissues during 

 the larval period between the ninth and forty-second day of embryonic life. He 

 traces this process, using serial sections, and gives a detailed account of the anatomy 

 and histology of the electric organs, the development of which gives a strong clew 

 to the probable development of the electric tissues in the other mormyrid fishes. 



Dr. Edwin E. Reinke studied the origin of the dimorphic spermatozoa of 

 Strombus and shows that the apyrene spermatozoa in their adult condition are de- 

 void of nuclear material and may serve as nurse cells to the eupyrene spermatozoa 

 or liberate some substance which may activate or sustain the eupyrene sperm. The 

 eupyrene spermatozoa are the only ones concerned in the direct act of fertilization. 



Professor E. W. Gudger presents a scholarly review of all literature relating to 

 the spotted eagle ray, and gives an exhaustive account of its anatomy, habits, and 

 distribution. 



No. 211. Papers from the Department of Marine Biology of the Carnegie Institu- 

 tion of Washington. Vol. VII. Octavo, 128 pages, 9 plates, 19 text 

 figures. Published 1915. Price $1.50. 

 This book contains the following papers, not sold separately: 



WATSON, J. B., and K. S. LASHLEY. Homing and Related Activities of Birds. 75 



pages, 7 plates, 7 figs. 



WATSON, J. B. Studies on the Spectral Sensitivity of Birds. 19 pages, 2 figs. 

 LASHLEY, K. S. The Acquisition of Skill in Archery. 14 pages, 2 plates, 9 figs. 



The principal object of these investigations was to secure exact data on certain 

 phases of distant orientation in birds. The field experiments were carried out 

 upon the noddy and sooty terns at Bird Key, Tortugas, Florida. Several flights 

 were made from distant poincs, e.g., Cape Hatteras, Mobile, and Galveston. Re- 

 turns were secured from places which lie north of the limits of distribution of these 

 (tropical) birds and from Galveston Harbor, which is nearly 900 miles over un- 

 broken water from Tortugas. This last flight establishes the fact that birds can 

 home over territory which can offer no visual landmarks. 



In order properly to control experiments on homing, it was necessary to go 

 further into the instinctive and habit life of the terns than was done in our 1907 



