Page:Proceedings of the Royal Society of London Vol 60.djvu/281

Rh the cases of apogamy recorded by Stange* were of this nature, but in JDoodia caudt, R. Br., which is the only one of his species yet investigated in detail,f the elevations, from which sporophytes developed, were situated on the under surface of the prothallus. This case appears to be interm ediate in ch aracter between Scolopendrium and the species investigated by De Bary.J

Several prothalli were found bearing sporangia ; these were grouped together in large num bers, usually upon the upper surface of the cylindrical process, but sometimes both above and below. Archegonia were situated close to the groups of sporangia. In the region of the prothallus, underlying th e group, a strand of tracheides was found ; in one instance this was connected w ith a spherical mass of tracheides developed to all appearance w ithin the venter of an archegonium whose neck had not opened. The tissue upon which the sporangia are inserted is thin walled, and its cells have g ran u lar contents ; it contrasts sharply with the cells of the prothallus which have a large vacuole and walls w hich stain m uch more deeply w ith hmmatoxylin. As in the case of Lastrcea dilat, the stages seen render it probable th at the spoi’angia follow the usual course of development. Two layers of tapetal cells are formed w hich surround a considerable mass of sporogenous tissue. Many of the sporangia fail to attain full development; they rem ain colourless, and in time w ither. A fewr have been found, however, with a well developed annulus of a dark colour; these contained spores which have not, however, been examined in detail.

In one case two ram enta overarching a group of sporangia were seen. A t first sight it seemed possible th at they m ight correspond to an indusium, but, when taken in connexion w ith another example in which a cylindrical process, which bore sporangia laterally, term inated in an apogamously produced bud, another explanation appears more probable; this will be referred to again below.

It is worthy of note that another variety of this species has been found to produce young plants, the first fronds of which bore numerous prothalli while still in connexion w ith the stem.§ The prothalli on which these plants appeared had been subjected to repeated subdivision, a process which in other species|| has been found to induce apogamous development of the sporophyte. Unfortunately nothing is known of the m anner in which these peculiar plants of Scolopendrium were produced, but it is possible that they arose apogamously. The case of would then be com-

t Heim, ‘ Flora,’ 1896, p. 329. X Loc. cit. § In a paper by Mr. E. J. Lowe, read at the Linnean Society, February 20, 18J6. H Stange, loc. cit.
 * ‘ Ber. der Gesellseh. f. Bot.,’ Hamburg, 1883, p, 43.