and Laboratory Methods. 2711 



killing dehydrate rapidly, clear in cedar oil and preserve in paraffin. Insect 

 tissue loses its finer structure if preserved in alcohol and becomes more difficult 

 to section. No method of softening chitin vi'as found which left the tissues unin- 

 jured. Proper fixation, careful embedding, sharp knives, and patience are nec- 

 essary for good sections of hard chitinous structures. c. a. k. 



Eycleshymer, A. C. The Early Development of The fish were taken by spearing in 

 LLpiilostcns ossnts. Dec. Pub. Univ. Chi- lakes in Michigan and Wisconsin in 

 cago, 10: 259-276,015. 17, 18, 1903. , , ^, ^.r- ■ ,, r 



■^^ ^ '^ June, and the eggs were artificially fer- 



tilized. Eggs and sperm obtained by stripping were more favorable than those 

 obtained by excision. Formalin in 8 to 10 per cent, aqueous solution followed 

 by haemalin surface staining clearly defined the cleavage grooves ; chrom-acetic 

 to which a little 1 per cent, osmic acid had been added also gave most excellent 

 results. Material killed in corrosive-acetic was most satisfactory for sectioning, 

 and for section staining. Picro-acetic and picro-sulphuric while fairly good for 

 larval stages caused distortion and swelling of early stages obscuring the cleav- 

 age furrows. c. A. K. 



GENERAL PHYSIOLOGY. 



RAYMOND PEARL, University of Michigan. 



Books and Papers for Review should be Sent to Raymond Pearl, Zoological Laboratory, 

 University of Michigan, Ann Arbor, Mich. 



Loeb, J. Ueber die Befruchtung von Seeigel- ^s a result of his experiments on the 

 eierm durch Seesternsamen. Arch. f. d. ges. cross-fertilization of sea-urchin eggs 

 y • • j-3 j5 ' 9 J- ^j,.]^ Star-fish sperm, Loeb finds that 



the composition of the solution in which the eggs are placed is the determining 

 factor for successful crossing. In ordinary sea water or in a van't Hoff' s solu- 

 tion (a solution with the following substances in the proportions indicated : 

 100 NaCl, 7.8 MgCl.^, 3.8 MgSO^, ±'2 KCl, 1 CaCl2) to which has been added 

 0.1 to 0.2 ccm. h/10 NaOH, or 0.4 to 2 ccm. 5,8 m NaHCO,,, per 100 ccm. of 

 the solution, eggs of Str-ongylocentrotus purpiiratus can be easily fertilized with the 

 sperm of the same species. In these solutions it is not possible to fertilize any, 

 or at best but very few of these eggs with star-fish sperm {Asterias ochracea was 

 the form used). If, however, there be added to the van't Hoff solution a slightly 

 larger amount of sodium hydroxide (0.3 to 0.4 ccm. n /\i) NaOH per 100 ccm. 

 of the solution) the eggs are fertilized by the star-fish sperm quickly and in 

 large numbers. The experiments show that besides the NaOH (or hydroxylions) 

 Ca and Na ions are necessary both for the ordinary fertilization and hybridiza- 

 tion. The only anions necessary beside the OH ions are CI ions. Aside from 

 the principal results here stated some of the details of this work, as brought out 

 by the author, are very interesting and suggestive, as for example the fact that 

 the hybrid larvae formed skeletons, this being of course a purely sea-urchin char- 

 acter. Lack of space forbids further mention of this interesting and important 

 work here. R. p 



