

160 BOTANICAL GAZETTE [February 



this species. A study of this material makes it clear that cleavage 

 polyembryony does not occur, but each archegonium produces 

 only a single embryo. The group of rosette cells is present, but no 

 divisions were found within these cells producing rosette embryos, 

 as they do occasionally in Abies. Picea, therefore, is a step farther 

 removed from Pinus in having eliminated all traces of cleavage 

 polyembryony and rosette embryos, except the tier of rosette cells. 

 Although the available material of Larix was also somewhat 

 limited, several outstanding features may be described with cer- 

 tainty. Like Picea and Abies, only one embryo is produced per 

 archegonium. Except for the different appearance in size and pro- 

 portion, the embryo of Larix is very similar to that of Picea. The 



4 collateral primary suspensor cells become very long and slender, 

 without the abrupt twists or turns found in the pine suspensor, and 

 the secondary additions of the suspensor have similar characteris- 

 tics. The older divisions of the suspensor collapse as the newer 

 embryonal tubes elongate from the base of the embryo. A group 

 of rosette cells is present, but these collapse without forming 

 embryos, and the basal plates are again large, obstructing a good 

 view of the former in many cases. 



Pseudotsuga furnishes a rather interesting variation from the 

 embryos already described. This form is like Picea and Larix in 

 producing only one embryo from each egg. It has no rosette cell. 

 but the uppermost tier of walled cells elongates to form the sus- 

 pensor, a condition shown in less than 5 per cent of the pine embryos 

 {Pinus Banksiana). This occurs as a regular feature in Thuja (12) 

 and many other conifers. As the suspensor elongates, the contents 

 of the archegonia shrink and harden, and persist as flattened, deeply 

 stained structures attached to the upper ends of the transparent 

 suspensors. A very thick layer of protoplasm or other substance. 

 in the position which corresponds to the basal plate, stains more 

 deeply than the remaining regions of the withered archegonia. 

 Although cleavage polyembryony does not occur, a larger number of 

 embryos is produced than in Abies, Larix, or Picea. This is due 

 to the existence of a larger number of archegonia, which range from 



5 to 8. The suspensor cells do not collapse early, as in Larix and 

 Abies, and although the embryos were never found splitting into 



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