THE DEVELOPMENT OF THE EMBRYO IN PINUS PINAS- 

 TER, SOLAN D, WITH SOME NOTES ON THE LIFE 

 HISTORY OF THE SPECIES IN CAPE COLONY. 



Bv W. T. Saxtox, M.A. 



IXTRODUCTIOX. 



In Coulter and Chamberlain's " iMorphoiog}- of Spermatophytes " 

 (5) the following remarks are made in connection with the em- 

 bryogen" of Conifers : — 



" The whole subject is in need of more detailed investigation. While the 

 earlier stages of the embryo are fairly well known, our knowledge of the 

 development of the embryo proper is little more than an outline." 



It was mainly with the object of filling in this outline for Pimis 

 that the present study was undertaken. A cursory examination 

 of certain other conifers, especially Callitris and Podocarpiis, indicates 

 that the sequence of events, in later stages, is very much the same 

 for all genera. 



METHODS. 



Material was collected and fixed towards the close of 1907 and 

 again at the end of 1908 and during January, 1909. The first 

 series was fixed in chromacetic acid, the second in Picro-acetic 

 corrosive-sublimate in the same proportions as used for the Arche- 

 gonium and fertilisation stages by the writer (14). It may be added 

 that the fixation of the second series was undoubtedly superior to 

 that of the first. Delafield's Haematoxylin has been almost the 

 only stain employed. In a few cases the triple stain was used, but 

 was less satisfactory. 



SCOPE OF WORK. 



The development of the proembr^^o has been fully described by 

 various writers, the latest contribution being that of Kildahl (iij. 

 The series obtained by the writer include all stages of proembryo 

 development and entirely confirm the account just cited. 



The present communication therefore starts with the elongation 

 of the suspensors and gives a connected account of the development 

 up to the time when the main morphological region sare distinctly 

 differentiated. 



DESCRIPTIOX. 



It is commonly believed that the elongation of the suspensors 

 forces the embryo cells down into the prothallus, rupturing the base 

 of the Archegonium in the process. Hofmeister (10) states : — 



"The increase in the length of the proembryo ultimately ruptures the base 

 of the corpusculum." (.Vrchegjnium). 



Apparently this statement has never been contradicted, but the 

 writer is convinced that, strictly speaking, the embryo makes its 

 way into the prothallus by quite another means. 



If this were a purely mechanical process, not only would it be 

 likely that the rosette v/ould be pushed upwards rather than the 



