September 1, 19111 



SCIENCE 



279 



habits and parasitism of Erameria canescens, 

 xeno-parasitism (experimental production of 

 parasitism), and the origination of parasit- 

 ism, the latter a most suggestive philosophical 

 discussion. 



" Some Contributions to the Life History 

 and Cytology of the Smuts," by B. F. Lut- 

 man (Transactions Wisconsin Academy of 

 Sciences, 1910), adds materially to our knowl- 

 edge of the development of these plants. 



" A Catalogue of the Flowering Plants and 

 Ferns of Connecticut," by a committee of the 

 Connecticut Botanical Society (Geological 

 and Natural History Survey, 1910), attempts 

 to give " an accurate and authoritative cata- 

 logue of all the plants known to grow with- 

 out cultivation in Connecticut," and it ap- 

 pears to have accomplished this purpose so 

 far as the flowering plants and ferns are con- 

 cerned. In the summary we learn that there 

 are included in the catalogue 74 species of 

 pteridophytes (all native) and 1,407 native 

 spermatophytes, with 461 introduced species. 



In passing we should notice favorably 

 Wettstein's " Handbuch der Systematischen 

 Botanik " (Leipzig, Franz Deuticke, 1910- 

 11), a thick volume of over nine hundred 

 pages. Seven great phyla (" Stamme ") are 

 recognized, viz., Myxophyta (" conventionallj" 

 placed here), Schizophyta, Zygophyta (in- 

 cluding Peridinieae, Bacillarieae and Conju- 

 gatae), Phaeophyta, Rhodophyta, Euthal- 

 LOPHYTA (including Chlorophyceae and Fungi} 

 and CoRMOPHYTA (including Archegoniaiae 

 and Anthophyta). The work will prove a 

 most helpful one for the student of systematic 

 botany, and merits translation into English. 



Charles E. Bessey 

 The TJniveesitt of Nebraska 



SPECIAL ARTICLES 



ON THE STEREOTROPISM OF EMBRYONIC CELLS 



In a former paper, describing the develop- 

 ment of nerve fibers in foreign media, the 

 hjTpothesis was advanced' that the fibers re- 

 quire some form of solid support in order to 

 carry out the growth process, which, as was 



^ Journ. of Exp. Zool., Vol. 10, 1910. 



shown, is a form of protoplasmic movement. 

 The present communication presents in brief 

 form the results of some experiments on the 

 movement of embryonic cells, which show be- 

 yond doubt that the hypothesis holds true for 

 the cells of the mesoderm and the medullary 

 tube of the frog embryo. With reference to 

 the outgrowing nerve fibers, however, the ob- 

 servations are too few to warrant any more 

 definite statement about them at present. 



In the previous experiments the solid sup- 

 port was given in the form of a fibrin net- 

 work, derived from the clotting of fresh 

 lymph. In the present study spider web was 

 used to support the small pieces of trans- 

 planted tissue immersed in various fluid 

 media. The object of the investigation being 

 to compare the behavior of embryonic cells in 

 the same medium, with and without solid sup- 

 port, two sets of preparations were made; one 

 in which the tissue was placed in a simple 

 hanging drop in a moist chamber, the other in 

 which the drop was supported from below by 

 a closely woven spider web. The moist cham- 

 bers were made by sticking glass rings to 

 object slides by means of vaseline and sealing 

 to the ring a cover slip with the culture drop. 

 The spider webs were tightly spanned over 

 the upper surface of the glass rings prior to 

 fastening the latter to the slide ; the pieces of 

 tissue to be studied were then transferred in 

 very small drops of fluid to the web, and the 

 preparations immediately covered by cover 

 slips, also coated with the web, so that the 

 pieces of tissue remained supported between 

 two layers of the fabric. 



The fluid media which were employed were 

 purposely varied considerably; physiological 

 salt solution, Locke's solution and Ringer's 

 solution (without sugar) of full strength and 

 diluted, and also defibrinated frog's serum, 

 were all used. The best results were obtained 

 with the defibrinated serum, but some positive 

 results were obtained with all the inorganic 

 solutions used, showing, in agreement with 

 the work of M. R. and W. H. Lewis," com- 

 patibility of wide range between tissue and 

 medium. 



'Anatomical Record, Vol. 5, No. 6, .June, 1911. 



