360 Transactions. 



In the case of the young plants of L. BiUarclieri, L. volubile, and L. 

 scariosum there is no trace of protocorm, nor of protophylls. 



Development of Stem and Leaves. 



In the early stages of the voung plant of L. cernuum the main axis of the 

 plant cannot be designated a stem, for it consists merely of the persisting 

 protocorm surmounted by the fused bases of the protophylls ; but, after 

 five or six protophylls have been formed, they are seen to aggregate at a 

 point on the upper extremity of the protocorm. and a definite stem apex 

 becomes differentiated there (Plate XXXI, fig. 3). The development of the 

 stem is very late in L. laterale, but when this does take place it is initiated 

 by the aggregation of the protophylls at some particular point or points 

 (Plate XXXI, figs. 6-8). 



In the case of L. Billardieri, L. voluhile, and L. scariosum the earhest 

 stages in development of stem were not observed; but a comparatively 

 early stage was that when the stem axis showed as a simple, slender, cyUn- 

 drical stem, bearing only a few scattered minute scale leaves (Plate XXXI, 

 fig. 10). 



The regular foliage leaves of L. cernuum and L. laterale develop immedi- 

 ately upon the stem apex being differentiated. 



The stem axis of the young plants of L. Billardieri , L. voluhile, and L. 

 scariosum remains destitute of leaves till the apex has reached the surface 

 of the ground. In the case of L. Billardieri, the young stem was observed 

 thus leafless for 1-6 cm. in height, in L. voluhile for 1-4 cm., and in L. 

 scariosum for 1-10 cm. 



A few chlorophylless scale-hke leaves are very often to be seen on that 

 part of the stem which is underground. As soon as the stem apex has 

 risen above the surface of the ground the usual assimilatory leaves are 

 immediately developed, those of L. Billardieri being broad and large com- 

 pared with the size of the plant, whilst those of L. volubile and L. scariosum 

 are small and needle-like. 



The foot of the single young plant of L. densum found was situated 

 about 4 cm. below the surface of the ground. The stem for this length was 

 leafless, and above the leaves were of the usual acicular form. 



General Remarks about the Young Plants of Lycopodium. 



In his paper on " The Prothallus of L. clavatum.''* Lang, starting from 

 the assumption that " in the L. cernuum type the primitive form of pro- 

 thallus and young plant has been most completely retained," suggested 

 that from this type other forms have been derived "in which the gameto- 

 phyte is adapted to the saprophytic mode of life." He suggested that 

 the various species of Lycopodium so far studied could be arranged in a 

 series illustrative of the gradual reduction of protocorm and development 

 of the foot consequent on the increasing dependence of the young plant 

 upon its prothallus. 



There is nothing arising from this present study to be brought forward 

 in contradiction to this suggestion. The important development of the 

 protocormous organ in the young plant of L. laterale may be considered 

 either as a later specialisation of the type of protocorm seen in L. cernuum 

 or as representing an earUer stage in the history of the organ. L. Billardieri, 



* Ann. of Bot., June, 1899. 



