ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 791 



higher Invertebrata (Arthropoda, Mollusca) and the lower Vertebrata 

 (Pisces, Cyclostomata), not only of cardiac but of vasomotor and 

 secretory nerves and of nerves aflfecting the respiratory and other 

 nervous centres. 



The respiratory centre of the Octopus seems already to offer a 

 most interesting field for research. 



In the meantime it is jirobable that investigations into the in- 

 fluence on the metabolism of cardiac muscle exercised by vagus 

 (inhibitor) and sympathetic nerve (accelerator) respectively would 

 produce results of the greatest interest. If it could be shown that 

 the true vagus fibres of a tortoise or a frog in any way tended to 

 increase conductive metabolism, while the sympathetic favoured the 

 destructive processes, a step would already be taken in harmonizing 

 the phenomena presented by Mollusca and Vertebrata and in forming 

 a general interpretation applicable to all. 



Physiology of the Unstriated Muscles of Invertebrata.* — From 

 a study of the unstriated muscles of Invertebrata, M. H. de Varigny 

 concludes that no essential difference exists between the physiology of 

 the unstriated and the striated muscles. The unstriated muscles under 

 certain conditions even surpass the striated ones from a physiological 

 point of view. In the Invertebrata their role is an important one, for 

 whilst remaining the active agents of the movements for nutrition, 

 they become the agents of voluntary movements and in contact with 

 the nerves of voluntary motion derive such an energy and acquire so 

 perfect a physiological development, that they occupy in the functional 

 hierarchy a superior rank to that of certain striated muscles ; whilst 

 the striated muscle is the most perfect and most developed contractile 

 agent and the one whose evolution is most advanced. 



There is no ground for dividing the physiology of muscles into 

 two classes, the differences existing in certain points are not essential, 

 but of a secondary order only. 



Temperature Maxima for Marine Animals.t — Dr. J. Frenzel 

 commenced his observations on the influence of heat on marine 

 animals at a temperature of 40^ C. ; this was supported by a Holo- 

 thurian for two hours : a Diopatra died in about five minutes ; a 

 large Pleurohranchiea meckelii exhibited at first lively movements, 

 but after five minutes became torpid, but was not killed. Four 

 minutes were enough for a Scyllarus. As the Holothurian was the 

 largest of the animals experimented on, the author points out that 

 although the chief reason for its power of resistance might be sought 

 for in its size, yet the others were conquered too rapidly. We can 

 only say tliat the Holothurian is capable of resisting heat. 



In a second series of experiments he started at 30° C, and found 

 that Antedon began to break up in two seconds ; Diopatra survived 

 for eighteen hours, but Terehella was more sensitive, showing tlio 

 effect of heat at 25^ C. Aplysia can live at 2G^, Murex bore 30° C. 



• CornptcH RfiirluH, c. (\^S:>) pp. (\r>G-H. 



t Arch. f. Go.iarmut. rhywiol. (I'fliigor), xxxvi. (1885) pp. 458-GG. 



3 F 2 



