390 HOFMEISTER, ON 



size takes place in that one of the many free spherical cells 

 in the interior of the young capsule which is destined to 

 become the mother-cell of the large spores (PI. LVII, figs. 

 1- — 5). Pour new spherical nuclei (PI. LVII, fig. 3) are 

 formed on the outside of its primary nucleus, which becomes 

 more and more indistinct. Soon afterwards the primary 

 nucleus disappears (PL LVII, figs. 4, 4 J ), and six septa 

 meeting at angles of 120° suddenly appear in the mother- 

 cell (one between each two of the secondary nuclei), which 

 represent four tetrahedral special-mother- cells. In each of 

 the latter a spore is formed after a previous considerable 

 thickening of the wall, and during the very remarkable 

 increase in size of the special-mother-cells which follows this 

 thickening. The brown exosporium is in this species very 

 thick. In the perfect state three layers are distinguishable, 

 the middle one of which is of a glassy nature. The thick- 

 ened special-mother-cells are still in a good state of preser- 

 vation. The lines of division between each two are here 

 far more clearly distinguishable than in any phaenogamous 

 plant except the Malvacese (PI. LVII, fig. 7). At this stage 

 of development a slight pressure separates the special- 

 mother-cells, each of which contains a spore (PI. LVII, fig. 

 7*). In a manifestly diseased state of S. Martensi I have 

 seen the disproportionately thick exosporium composed of 

 prismatic (or, to speak more accurately, of truncate-pyramidal) 

 fragments ; the spore had remained much smaller than usual 

 (PL LVII, fig. 8). 



During the formation of the outer membrane of the large 

 spores of all the species which I have examined, the spheri- 

 cal nucleus usually lies close under the place at which the 

 three prominent ridges of the exosporium unite (PL LVII, 

 fig. 7).* It increases rapidly in size, and its nucleolus 

 disappears. Afterwards numerous vesicular bodies appear 

 within it (PL LV, figs. 13, 14). As the spore approaches 

 maturity it appears to be dissolved : I was never able to 

 find it in those spores which entirely fill the macrospo- 

 rangium.f 



* If the young spore lies for some time in water, the nucleus disappears. 



f Mettenius appears to assume that the nucleus of the spore gradually expands 

 until it attaches itself at all points to the inner wall of the spore-cell ('Beitr. 

 zur Botanik,' H. i, p. 7). I have never seen anything indicative of such a 

 process. 



