8 Journal of the Mitchell Society {^July 



ALTERNATION OF GENERATIONS IN PADINA 



JAS. J. WOLFE 



While at work on the life history of Padina at the Fisheries Laboratory 

 at Beaufort it seemed worth while to test the theory of alternation of gen- 

 erations in such plants by the cultural methods devised by Hoyt (Bot. Gaz., 

 Jan., 1910). Numerous cultures were made during the summer of 1910 

 and the next — all having but indifferent success. They were repeated in 

 1912 with somewhat better results. The cultures of Tetraspores produced a 

 total of 134 male, 154 female, and no tetrasporic plants. Those from 

 fertilized eggs were somewhat less conclusive. Nevertheless, the evidence 

 from cultures strongly supports the view that in Padina there is a real 

 alternation of sporophyte with gametophyte. 



GESTATION IN THE NURSE SHARK, GINGLYMOSTOMA 

 CIRRATUM 



E. W. GUDGER 

 A brief description was given of the breeding habits and of some points 

 in the embryology of this shark, which was studied at the laboratory of 

 the Carnegie Institution at Tortugas, Florida, in June and July, 1912. 

 A brief account has been published in the Year Book for 1912 of the 

 Carnegie Institution of Washington, Department of Marine Biology, 

 pages 148-150. 



HYBRIDIZATION EXPERIMENTS ON FROGS 



W. C. GEORGE 

 Chorophilus n. feriarum was crossed with Acris gryllus. About half 

 of the egg segmented. (In the pure Chorophilus control practically all 

 the eggs segmented). The development was markedly retarded and was 

 abnormal. The conspicuous abnormalities concerned the behavior of the 

 yolk pole. Thus segmentation at this pole was not perfect, and the 

 closure of the blastopore was interferred with in such wise that there 

 developed the well known abnormal type produced in so many ways, 

 characterized by a large blastopore area and the differentiation of the 

 neural plate. 



THE TOXICITY OF COTTONSEED MEAL 



W. A. WITHERS, J. E. BREWSTERj L. E. WILLIAMS, AND J. W. NOWELL 

 WITH THE COLLABORATION OE R. S. CURTIS AND G. A. ROBERTS 



The authors conclude from experiments, some of which have been 

 published :* that the toxicity of cottonseed meal is due to a constituent 

 and Journal of Biological Chemitry, Volume XIV (1913), pp. 53-58. 

 group of the proteins, probably one containing loosely bound sulphur. 

 They suggest some form of iron as an antidote having found with Bel- 

 gian hares that citrate of iron and ammonia (0.7 gms. daily) is effective 



♦rroceedings Society for Promotion Agricultural Science, 1912, pp. 19-21, 



