312 Scientific Proceedings, Royal Dublin Society. 



are clearly seen. 1 If now we compare any one of these leaves with the struc- 

 tures marked A, in fig. 2 of this Plate, and consider that in both vegetative 

 bud and male bud they are limited to the respective leaves and microsporo- 

 phylls, one feels justified in considering the dorsal sacs of the microsporophyll 

 of Larix and other Abietineae as really the paired canals of the vegetative 

 leaf. If, as is commonly believed, the microsporophyll is a differentiated leaf 

 carrying sporangia, it would, in any case, be the more natural interpretation. 

 Further, while in Larix the cavities are confined to the apical knob, this is 

 not so, for example, in Cedrus atlaniica, as illustrated in text fig. 2 (A). 

 Here the knob is thin and solid, but the canals of the pedicel turn out and 



Fig. 2. — Canal arrangement in microsporophyll of Cedrus allantica. x 20. 



A. Longitudinal section. 



B. Transverse section. 



The canals in both are marked C. 



run dorsally, as shown, to the end of the sporangia. In fig. 2 (B) they are 

 seen to be paired, and here the cavities are obviously the homologues of those 

 in the leaf. Eemembering that Miss Starr admits that the resin cavities of 

 the leaf develop just like the alleged abortive sporogenous tissue in the sporo- 

 phyll, it would appear that, so far as the evidence goes, we must regard the 

 apical cavities, when present in the microsporophylls, at any rate of the 

 Abietineae, as merely resin or mucilage cavities. 



Before leaving the question of these cavities, it is worth noting that a com- 

 parison with other male buds shows that in the case of Abies, Picea, and Pinus 

 there is no visible cavity, or only a very small one ; in Cedrus atlantica, the 

 condition already described prevails, while in Pseudotsuga alone of those 



1 The bud of Larix, it may be noted, is peculiar in this marked canal development in 

 the bud. It is not shown in Picea, Abies, Cedrus, Pimts, or Pseudotsuga. In these, at 

 most, sporogenous-like tissue appears in the site of the future canal. In Pseudolarix the 

 canals are to be seen ; but quite small when compared with Larix. 



