M. Miiller on the Development of the Lycopodiacese. 119 



Projecting into the interior of this cavity may now be discerned 

 a more or less roundish vesicle (figs. 7 c, 9 a). This is formed 

 of a very delicate, homogeneous membrane, perfectly hyaline, 

 therefore devoid of contents, and surrounded at its base by a 

 great number of smaller, more or less hyaline cells. This vesicle 

 is now apparently only the apex of the proper central axis of the 

 vascular bundle, as may be seen in figs. 7 and 9 ; and those cells 

 occurring at the base of the vesicle are the terminal ones of the 

 axis of the branch, the growth of which has not nearly kept pace 

 with that of the external cortical layer of the branch-axis, and 

 thus the cortical layer has become isolated and appears as the 

 sporangium. These cells subsequently acquire some green con- 

 tents ; but they undergo no further development, and exist in 

 the perfect oophoridium merely as a compact mass of cells out 

 of which project the four spores. 



The four spores however are formed in the vesicle produced 

 from the apex of the vascular bundle, and I have hitherto only 

 met with them in one single stage (fig. 15). Here they all four 

 lay closely grouped together and occupied the greater part of the 

 cavity of the vesicle. Each spore was already composed of a very 

 delicate, somewhat reddish-coloured membrane, which however 

 though still so young was already cellular. This last circumstance 

 has as yet remained perfectly incomprehensible to me. 



Should subsequent investigations show that this cellular struc- 

 ture is only apparent, and that this appearance coincides with the 

 ridge-like projections which so often occur on the pollen-grains 

 of the Phanerogamia, the question of the origin of the four ger- 

 minative spores would be very clearly solved. We should here 

 have in the interior of the oophoridium exactly the same law, 

 that the matter contained in a mother-cell in the pollen-grain is 

 formed, regularly, into four portions — subsequently four pollen- 

 grains. We should have, in this vesicle, an actual mother-cell. 



The further development of the spore is nothing more than a 

 gradual expansion of its membrane, which soon acquires a yellow 

 colour. It is quite empty, the form flat and compressed, and 

 tetrahedi'al in the same way as the antheridia-spores, so that a 

 long ridge may be observed on it (fig. 16). Little elevations 

 also soon show themselves upon it, — a sign that the membrane is 

 becoming thickened by the deposition of membranous matter. 

 As the spore increases in size however, the vesicle in which it 

 was formed disappears, and the four spores, which were originally 

 situated directly on the summit of the central axis, now lie scat- 

 tered in the four projecting lobes of the spore (sporangium?). 

 They go on swelling and becoming more thickened, until they 

 are at last found in that condition which was described in § 2. 



The course of development of these spores must be very clearly 



