1140 Journal of Applied Microscopy 



when oxygen is admitted. Warming the eggs to 32° or 33° C. for from two to 

 four minutes causes the clear areas to appear, and segmentation to occur, after 

 the return to sea water of ordinary temperature. Segmentation is also caused by 

 exposing the eggs to the action of sea water in which either ether, or alcohol, or 

 chloroform has been dissolved. In all cases division did not occur until the 

 eggs were brought back into ordinary sea water. In his theoretical conclusions, 

 drawn from these experiments, the author is inclined to abandon his earlier 

 view that karyokinesis is allied to the process of blood clotting, and states that 

 he believes " that whatever the details of the process may prove to be, the essen- 

 tial basis of karyokinetic cell division is the production of localized areas of 

 liquefaction in the protoplasm." In view of the great ease with which Arbacia 

 eggs can be made to segment by a variety of stimuli of different physical and 

 chemical character, such a broad generalization, having as a basis the phenomena 

 shown by these eggs under a particular set of conditions, seems to be of uncer- 

 tain value. R. P. 



Carlgren, 0. Ueber die Einwirkung des con- ^j^g f^^g^ ^f ^.^ese papers makes a note- 



stanten galvanischen btromes auf niedere '^ '^ 



Organismen. Arch. Anat. u. Physiol. Abth., worthy advance in our knowledge of 



1899 pp^49-76, I Taf. ^^^ gl=fect of the constant current on 

 Ueber die Einwirkung u. s. w. : Zweite Mitth. 



Versuche an Verschiedenen Entwicklungs- organisms, since it demonstrates the 



stadien^emiger Evertebraten. Ibid, 1900, importance of the kataphoric, or SO- 



called " osmotic" action of the current. 

 It is principally given to an account of the electrotactic response of Volvox. 

 The sense of the reaction is at first kathodic, but later changes to anodic. Strik- 

 ing changes in the form of the body are produced by the current. The anode 

 side of the colony becomes crumpled, while the kathode side is correspondingly 

 swollen out. The parthenogonidia move to the anode side of the colony. These 

 changes in body forms and movements of the parthenogonidia are entirely passive 

 phenomena, the anode crumpling and kathode swelling occurring in colonies 

 which have been killed in formalin in the same way as in living specimens. 

 Various Protozoa killed in weak formalin or ether solution show the same 

 changes in form under the action of the current. Carlgren concludes that the 

 purely physical, kataphoric action which produces these results is of very great 

 significance as a factor in the effect of the current on organisms. 



In the second paper descriptions are given of the electrotactic responses of a 

 number of marine invertebrates. The point of most general interest is in regard 

 to the reactions of the larva; of certain echinoderms {Strongylocentrotus lividus, 

 Spharechinus granulans, Ophiothrixfragilis, ?iuA Aster acanthion glacialis). Young, 

 free-swimming stages of these forms gave no response whatever, while older 

 larvae, Plutei and Bipennaria;, became oriented and went to the kathode. Theor- 

 etical discussion of the results is left for a later paper. No new methods of 

 work are described. R. p. 



Warren, E. On the Reaction of Daphnia -pj^^ experiments described in this 

 magna (Straus) to Certain Changes in its ' 



Environment. Q. J. Mic. Sci. N. S. 43 : paper have to do with the effect on 



'99-224, 1900- Daphnia of certain changes in the con- 



ditions of life. It was found that the time of killing in solutions of NaCl of 



