1. Some animal species-crossings in nature with analyses of similar ones in cultures, together with some fundamental questions. Discussed

   • G. Falkenström

   OriginalPaper Pages: 217 - 284

2. Untersuchungen Über Mutation bei Tabak

   • D. Tollenaar

   OriginalPaper Pages: 285 - 294

3. Experimental production of haploids in nicotiana rustical L

   • M. A. Ivanov

   OriginalPaper Pages: 295 - 397

4. Über die pseudogame Fortpflanzung bei Potentilla

   • G. Gentscheff

   OriginalPaper Pages: 398 - 408

5. Errata

   • G. Falkenström

   Erratum Pages: i - i