474 EXPERIMENT STATION RECORD. 



of important articles published during the year 1907 relating to cellular biology, 

 variation, heredity, evolution, biological theories, and related topics. 



The method and arrangement of biological studies, S. Tschulok (Das 

 System dcr Biologie in For seining und Lehre. Eine Historisch-Eritische Studie. 

 Jena, 1910, pp. 409; rev. in Zentbl. Allg. w. Expt. Biol., 1 (1910), No. 15-16, 

 pp. 519-523; Arch. Rassen u. Gesell. Biol., 7 (1910), No. 6, pp. 750, 751).— 

 This work, which is a historical and critical study of biology, outlines the 

 historical phases through which the botanical and zoological studies have 

 passed. These periods have been characterized by the methods of study 

 prevailing at the time, rather than as descriptive, historical, observational, 

 comparative, and experimental. The author makes 7 gi-oups of biological prob- 

 lems, as follows : Taxonomy, division of organisms in the groups ; morphology, 

 conformity to type ; physiology, life processes of the organism ; ecology, adapta- 

 tion to environment; chorology, distribution in space; chronology, distribution 

 in time ; and genetics, origin of organic groups. 



The cultivation of tissues of the chick em.bryo outside the body, M. T. 

 BuREOWS (Joiir. Amer. Med. Assoc, 55 (1910), No. 2!,, pp. 2057, 2058).— Fol- 

 lowing the method which Harrison employed with frogs, the author isolated 

 neural tubes, heart myotomes, and slcin taken from 60-hour-old chick embryos 

 and cultivated them in blood plasma obtained from healthy adult chickens 

 under ether anesthesia. 



The method practiced was to place the isolated fragments of tissue in a drop 

 of the uncoagulated plasma on a cover glass, which was then inverted and 

 sealed to a hollow slide and incubated at 39° C. The plasma immediately 

 coagulated about the tissue and held the fragment firmly fixed. So prepared 

 the specimen can be readily observed at all times under the microscope. 



The success of the method depends on maintaining absolute asepsis and pre- 

 venting undue chilling of the embryos or the completed specimens either dur- 

 ing preparation or the later observations. The plasma is obtained by exposing 

 the carotid artery and inserting a cannula previously sterilized in olive oil. 

 The blood is collected in sterilized, paraffin-coated tubes, which are cooled im- 

 mediately by being plunged into an ice-salt bath. The blood is then centrifu- 

 galized by placing the tubes in larger centrifuge tubes which contain a mixture 

 of salt and ice. The supernatant plasma is removed by means of parafiin- 

 coated pipettes and transferred to paraffin-coated receptacles, which are kept 

 in a refrigerator until used. 



The most actively growing elements in the preparations were the interstitial 

 connective tissue cells, which spread into the plasma either as single cells or 

 a layer of cells between the second and twelfth hours of incubation, as a rule, 

 the growth continuing for from 6 to 14 days. The muscular elements grew 

 much less frequently and cellular outgrowths from them were observed in only 

 about 3 per cent of the experiments. The outgrowths take place from the 

 myotomes of the heart in the form of short chains of striated cells. The out- 

 growth from the nerve cells consists of long axis-cylinder processes, which 

 present the same morphological appearances and react in the same way to 

 specific nerve stains as those of the chick embiyo. 



Further data regarding the sex-limited inheritance of the barred color 

 pattern in poultry, R. Pearl and F. M. Surface (Science, n. ser., 32 (1910), 

 No. 833, pp. 870-87-'/). — A record is given of results obtained in the F2 genera- 

 tion of crosses between Barred Plymouth Rock and Cornish Indian Game 

 fowls, in continuation of earlier work (E. S. R., 23, pp. G74, 778). In all 670 

 adult Fa chicks were recorded, from all possible matings inter se and. with 



