LIMNOCODIUM IN THE UNITED STATES. 317 



profound physiological modification in adaptation to changed 

 conditions of life." 



In the summer of 1905, as already pointed out, this medusa 

 appeared in considerable numbers in the aquaria of the Botanical 

 Garden of Munich. In a recent paper (Zeits.f. allgemeine Physiol., 

 Bd. VII.), Maas has recorded a series of experiments made to 

 test the reactions of the medusae to various stimuli, chiefly 

 chemical and mechanical, with brief references also to the in- 

 fluence of temperature. Experiments made with physiological 

 salt solution confirmed in a general way those of Romanes al- 

 ready considered. For example, specimens when first placed in 

 the solution showed quickened, spasmodic and heterochronous 

 contractions, followed later by collapse and finally by death. If 

 left in the solution for only ten minutes and then returned to the 

 normal water the irregularity gradually disappears and the pulsa- 

 tions become synchronous and normal. That these reactions were 

 not due to any difference in temperature he proves by control 

 experiments made on various specimens at the same temper- 

 atures in fresh water, and even in water at very much lower 

 temperatures. 



He also tested the reactions of emarginated specimens in the 

 salt solutions and found the same spasmodic contraction as ob- 

 served in the uninjured specimens. A brief summary of the 

 comparative effects of KC1 and NaCl is given, from which it 

 would appear that the former tends to inhibit reactions, while the 

 latter serves as an active stimulus, though of a very irregular or 

 heterochonous character. 



Maas also points out the somewhat conflicting results of Loeb's 

 experiments on Gonionemus and Poly orchis, those of Bethe on Olin- 

 dias, and Herbst on Obelia; and concludes that among marine 

 medusas there must be essential differences in their chemico- 

 physical relations. 



In the transfer of a delicate creature, such as medusas, from a 

 medium like sea water to that of fresh water it might naturally 

 be expected that reactions more or less remarkable should occur. 

 But what shall be said of similar reactions which follow the 

 transfer from a fresh-water medium, where if any soluble salts 

 be present it must be in homoeopathic doses of high attenuation, 



