DEPARTMI;nT OF MARINE BIOLOGY- 1 19 



perfectly with a portion of the abdomen, which had been cut from a mature 

 female and then fixed to a stick supported by wire "legs." This, I believe, is 

 the first successful experiment to cause a male insect to pair with a portion 

 of a female or even with one fatally disabled. 



(2) A small minnow, Atherina laticeps, was used to test the influence of 

 the osmotic pressures produced by solutions of glucose and cane-sugar, as 

 well as to ascertain the resistance of this fish to dilute and concentrated sea- 

 water solutions. Hypertonic solutions were found to be decidedly more 

 injurious than hypotonic, the fish often living longer in the latter than in 

 normal sea-water. No difference could be observed between the effects pro- 

 duced by the two kinds of sugars. This fish is rather delicate and not a 

 favorable subject for such studies. 



(3) A series of experiments were conducted to find, if possible, some rela- 

 tion between the extent of injury and the rate of regeneration, also to test 

 the influence of movement or activity on the regeneration rate, as well as the 

 influence of the nervous tissues. Finally, the effects of the metallic ions Ca, 

 K, Na, and Mg on regeneration were studied for comparison with the influ- 

 ences that these elements are known to produce on contractile tissues. _ The 

 animal used in these experiments was the very hardy jelly-fish Cassiopea 

 xamachana, so abundant in this region. I found Cassiopea favorable material 

 for such studies, since its circular shape and radial structure enables the 

 observer to perform several experiments on one and the same individual, 

 thus facilitating comparisons ; for example, a ring of tissue cut from the 

 periphery of this jelly-fish will readily begin to regenerate. Now, with such 

 a preparation one may remove the sense-organs from half the ring, then 

 insulate the two halves, causing one to cease pulsating while the other main- 

 tains its normal pulsations. Thus the influence of rest and activity may be 

 observed on the regenerating surface. Many such experiments are made 

 possible with this animal. 



Individuals having a number of mouth-arms removed regenerate these 

 arms at rates which vary as much as does the rate of regeneration between 

 the individual with one or a few removed arms and others with many arms 

 removed. In other words, I do not find it to be always the case that the 

 individual having the larger number of removed appendages regenerates 

 each of these arms more rapidly than will an individual with fewer removed 

 arms. I have not, however, up to this time, had an opportunity to make a 

 careful study of the measurements contained in my notes, and it may possibly 

 be that on calculating averages the results may accord more closely with 

 those of Zeleny, 



Tissues removed from various parts of the disk regenerate more rapidly 

 the nearer they are to the disk center and less rapidly as the periphery is 

 approached. Cuts of different shapes were made in the disk, and in all of 

 these experiments the manner of regeneration from the different parts of the 

 cuts was identical with that which Morgan has found for the regenerating 

 fish's fin. The detailed results of this investigation will be published by the 

 Carnegie Institution. 



Dr. P. A. Stromsten preserved about 450 embryos of the loggerhead turtle 

 in various stages of development, with a view to a determination of the 

 development of the venous system. He will be unable to report upon this 

 research until he has completed the study of extensive series of sections. 



