PREFACE 



In 1901 our Morphology of Spermatophytes, Part I, was j)ublished, 

 which comprised a presentation of the gymnosperms. It had grown 

 out of a special course given to graduate students for several successive 

 years, and although most of the ground had been traversed in this 

 way several times, the larger part of the material in the book was 

 taken from the contributions of other investigators. There was some 

 new material included, Init the chief contributions of the book were 

 certain illustrations and the organized presentation of the group as 

 a whole for research students. 



During the last decade the special course referred to has been 

 continued for successive generations of graduate students, with a 

 constantly widening range of material and from new points of view. 

 In addition to this extensive and repeated critical examination of 

 material, a number of special investigations have been carried on in 

 the laboratory. These investigations have been planned so that 

 there might be not only a research contact with all regions of the 

 gymnosperm series, but also a clearing up of unknown or doubtful 

 forms. These special contributions from the laboratory have aggre- 

 gated twenty-six since 1901, and have dealt with fourteen genera, 

 distributed as follows: in Cycadales. Dioon, Microcycas, Encephalar- 

 tos, Ceratozamia, and Zamia; in Ginkgoales, Ginkgo; in Coniferales, 

 Pinus, Thuja, Torreya, Phyllocladns, Podocarpus, and Dacrydium; 

 in Gnetales, Ephedra and Gnetum. This has enabled us to pre- 

 sent the living groups from an entirely different standpoint, and 

 to use many illustrations prepared in this laboratory. The present 

 account, therefore, is based upon our own work, supplemented by 

 the work of other investigators, rather than a compilation from liter- 

 ature, supplemented by occasional personal observations. 



Furthermore, the last decade has been one of unprecedented 

 activity in the investigation of gymnosperms, as a comparison of the 

 bibliography of the volume of 1901 with that of the present one will 

 indicate. In this period the number of titles has increased from 

 112 to 420, some of the additions being accounted for by the larger 



