1870.] Zoology. 291 



progress ; a man is to be kept in the chamber for six to eight hours, 

 and the work done is in the form of crank-turning. 



The Absence of Currents in Uninjured Inactive Muscle. — Pro- 

 fessor Hermann states that if the gastrocnemius muscle of the frog 

 be so prepared for investigation that no coutact between the cuta- 

 neous secretion and the surface of the muscle takes place, then, with 

 an exceedingly delicate galvanometer, only the very smallest deflec- 

 tion ef the needle is obtained. He concludes, therefore, that by still 

 greater care muscles can be obtained perfectly free from currents, 

 and regards previous observations of muscular currents as having a 

 very different significance to what has been supposed, being really 

 artificial phenomena due to certain accidents of manipulation. 



Pasteur s Views on Fermentation. — Professor Liebig disputes 

 Pasteur's theory that the decomposition of sugar in fermentation 

 depends on the development and multiplication of yeast-cells, and 

 that fermentation is only a phenomenon accompanying the vital 

 processes of the yeast. Liebig considers that Pasteur's researches 

 have not explained fermentation, but have only made known another 

 phenomenon — the development of yeast — which equally requires 

 explanation. 



Physiology of Sepia. — A series of interesting experiments have 

 been made by M. Bert on this subject. He finds that the excision 

 of the large supra oesophageal ganglion-mass causes no pain or 

 inconvenience to the animal, but simply deprives it of voluntary 

 motion. He hence infers it to be equivalent to the vertebrate cere- 

 brum. The- contents of the salivary glands, as also of the liver and 

 pancreas (so-called), are acid. The peritoneal cceca excrete uric 

 acid. Strychnia and curare have the same effect on this animal as 

 on vertebrates. 



Morphology. 

 Commensalism. — Professor Yan Beneden, in an interesting ad- 

 dress to the Belgian Academy of Sciences, proposes this word to 

 distinguish a group of animals hitherto confused with what he would 

 term veritable parasites. Commensal parasites, or commensals, do 

 not feed on the animal with which they are found, but hy it : they 

 are not destructive or injurious to their hosts, but often are of ser- 

 vice, if we may judge from the constancy of association and the satis- 

 faction which both parties seem to enjoy. Professor Van Beneden 

 distinguishes fixed and free commensals. Among the fixed we may 

 mention the various barnacles which are attached to whales and sea- 

 turtles ; the Anemone parasitica, which invariably is fixed to a shell 

 inhabited by a particular species of Hermit-crab, said to exhibit great 

 affection for the polyp it bears on its back ; many Polyzoa and Hy- 

 drozoa, which attach themselves to the carapaces of Crustacea, espe- 

 cially the hairy-looking Dromia of our southern coasts. 



