THE CHEMISTRY OF MEDUSA 



125 



SESSIONAL PAPER No. 22a 



a few seconds, but in 30 or 40 seconds these faded into irregular twitchings. It 

 became contracted and quiescent at the end of the first minute. On being replaced 

 in fresh-water a strong spasm occurred after five minutes had elapsed, and for 20 

 minutes there was no motion. Irritability continued for some hours, as proved by 

 pinching with forceps, but the effects of the sea-water immersion proved fatal. It 

 was found to live for some hours in brackish or very weak salt-water (1 in 12, or 1 in 

 15), and it lived for days in a still weaker solution (1 in 18). Marine jellyfish can- 

 not endure a high temperature, indeed 70°F. is fatal; but this fresh-water form with- 

 stood 100°F.— its pulsations being 80 per minute at 65° to 75°r., while they increased 

 to 130 per minute at, a temperature of 85°F. Freezing killed Orapedacustas, where- 

 as marine species have been frozen and on being thawed out, they swam about as 

 usual. Again, marine species survive for hours in saturated brine, as Eomanes 

 proved. There is a parallelism, as Dr. W. B. Carpenter long ago pointed out betwee a 

 morphological differentiation and physiological differentiation, and the physiologist 

 may well be impressed by the diverse animal forms, amongst the Metazoa, which are 

 sble to maintain a vigorous vitality in the midst of greatly changed or changing 

 external conditions. They have within themselves the power of compensating for these 

 changes in an extraordinary degree. Above all, the specialized and complex organiza- 

 tion of man possesses surprising capability of resistance to, or rather, independence 

 of, environmental changes. He is capable ^ of sustaining the highest as well as the 

 lowest extremes of temperature and of atmospheric pressure,' to quote from the dis- 

 tinguished authority just referred to. This resistance to varying external changes, 

 is an inherent potency by which organic individuality is to no small extent main- 

 tained. 



To return from this excursus to Professor Macallum's investigation, it seems 

 clear that while the inorganic composition of Aurelia and Cyanea has acquired com- 

 p?rative fixity, the adaptation of these forms to changes in chemical environment is" 

 incomplete and variable. When the salts in sea-water were less abundant than they 

 are now the medusse would, doubtless, acquire a fixed relation to the relatively con- 

 centrated potash salts, while more tolerant of the salts of soda, as they became more 

 concentrated. More than the usual amount of potash salts would be absorbed, in 

 order to retain the physiological equilibrium; but this excess would diminish as the 

 cells accommodated themselves to the altered relation between the potash and the soda 

 salts. The power of taking up sodium and magnesium compounds would increase 

 though not to such a degree as to take in tho full amount present in sea-water. Fur- 

 ther, the power to select lime would early approximate to the limit of the amount 

 in sea-water. 



The amounts, absolute and relative, are detailed in the following table: — 



a. ABSOLUTE AMOUNTS IN 100 PARTS. 





Sp. gr.* 



CI 



SO, 



CaOf 



MgOt 



K 



Na 



Total 

 Salts. 



Sea water, St. Andrews — April. . . 

 M n August, . 



1018-03 

 1023-79 



1023- 49 

 1022 78 



1024- 42 

 1023-52 



1-347 



1-7473 



1-7174 



1-6543 



1-6842 



1 7231 



0- 15126 

 0-20257 

 0-13363 

 0-18931 

 0- 11349 

 0- 12^45 



0- 04105 

 0- 05259 

 0 0515 

 0- 04943 

 0- 048785 

 0- 05375 



0-14888 

 0- 19344 

 0-17556 

 0-18377 

 0- 16946 

 0-18205 



0- 027184 

 0- 035395 

 0- 048745 

 0.033503 

 0 068935 

 0 048103 



0.74236 

 0-988235 



2 41704 

 3 -16566 



Sea water, Canso — /\ = - 1 ' 825° C. 

 Cyanea, Canso — J/\ = - 2 " 137° C. . 

 Aurelia' Canso— tA= -2'01° C . 



0-91898 

 0-89926 

 0-92^773 



2-98264 

 2-9279 

 3 00175 



* As compared with distilled water at 4° C . 



fG'.ven as CaO and MgO to facilitate comparison witn the tables of Dittmar and Forchhanjmer. 

 J Cryoscopic determinations on carefully filtered juice in each case. 



