and Laboratory Methods. 1185 



taxis of Oscillaria, diatoms and desmids, and the Gregarinidse. It is evident 

 that these phenomena of thigmotaxis are very important in the life of the 

 Protozoa. 



This importance is well shown by the effect of the thigmotaxis on the reac- 

 tions to other stimuli. The other reactions studied were the electrotactic and 

 the thermotactic. In regard to the electrotaxis it was found that among some 

 of the ciliates, individuals which were kathodically electrotactic when swimming 

 freely through the water, when in contact with a solid body (i. e., thigmotactic) 

 oriented themselves more or less transversely to the direction of the current with 

 the oral side of the body towards the kathode. This transverse orientation was 

 investigated in a number of forms. It is evidently the same reaction as that 

 which has been described by the reviewer (Amer. Jour. Physiol. Z\ 96-123) 

 and explained as due to the conflict between two sets of ciliary activities. 

 It is now shown to be also in part the result of the thigmotaxis of the animal. 

 The author confirms previous investigators as to the reversal of the cilia on the 

 kathode side of the body during the action of the current. The permanent 

 transverse electrotaxis of Spirostomum is thought to be a result of the thigmo- 

 taxis of the posterior end of the body. Professor Loeb's theory of the action of 

 the external electrolytes in electrotaxis is thoroughly examined and strong 

 evidence against it is presented. The effect of heat or cold is different accord- 

 ing as the animal is, or is not, in contact with a solid body. Many forms 

 (Euglena, Chilodon, Stylonychia, Spirostomum and others) cannot be made to 

 leave the bottom by heating. They die while still thigmotactic. 



The reactions of Stylonychia mytilus are described in more detail than those 

 of any other form and some interesting curves are given showing the relative 

 activities of the different groups of cilia at different temperatures. All the cilia 

 show maximal activity at two widely separated temperatures (5-10° and 

 25-35°C.) while the minimal activity of all is between 15° and 20°C. 



This excellent piece of work puts our knowledge of another of the reactions 

 of the Protozoa on a firm basis. R. p. 



Delage, Y., and Delage, M. Sur les relations In this note are presented the results of 

 entre le constitution chimique des produits rhemiral analvses of the sexual 



sexuels et celle des solutions capables de ^ome ciiemicai analyses or tne sexual 



determiner la parthenogenese. C. R. Ac. productsof the male and female in the sea 

 8ci. Paris, 131 : 1227-1229, 1900. ^^^^^.^^ Strongylocentrotus lividus. The 



starting point of the work is the idea that if, as has been stated, it is the Mg-ion 

 which causes the artificial parthenogenetic development of the egg, and if 

 normal development is the result of the same sort of a process, analysis ought 

 to show a greater proportionate amount of this salt in the sperms than in the 

 eggs. This was not found to be the case. The magnesium content of the 

 products of both sexes is essentially the same, so that normal fertilization cannot 

 depend merely on the bringing of more of this salt into the egg by the sperm. 

 This result in no way affects Professor Loeb's later views, which point to osmotic 

 pressure as the essential factor in the production of artificial parthenogenesis. 



