AN APOSPOROUS LASTREA. 481 



I was unable at the time of making the sketch which I exhibit to 

 determine its species. In this sketch, which enlarges the plant 

 considerably, the condition of the second frond is given as it 

 appeared in July. Shortly afterwards, as it began to show signs 

 of decay, I placed a small piece of loam behind it to stimulate the 

 prothallic growth, the result of which has been a partial resusci- 

 tation accompanied by a splitting up of the terminal prothallus 

 into several smaller ones, but no definite progress in the direction 

 of reproduction. 



Meanwhile, however, the next frond in succession grew on, 

 and at first showed no signs whatever of prothallic buds, per- 

 fecting, indeed, its normal growth entirely without a sign of them ; 



this completed, however, an irregularity appeared at trie top of one 

 of the basal pinnae, and very speedily others appeared at all points 

 and edges generally, root-hairs and prothalli being developed 

 simultaneously. At this stage, too, the flat surface of the frond 

 along the line of the rhachis broke out into an eruption of small 

 pimples, which very speedily assumed the perfect normal form 

 and size of prothalli ; so that at the time of writing (Oct. 23rd, 

 1892) the upper part of the frond is completely covered by a 

 bunch of prothalli of various sizes, all arising by simple budding 

 and extension of the cellular growth of the frond itself. 



At present the next frond in succession presents no abnor- 

 mality save a terminal expansion and furcation of the rhachis, 

 which, in conjunction with other specific characters now clear 

 enough, proclaim the plant to be a tasselled form of Lastwa, 

 presumably the old L. Pseudo-mas, var. cristata ; aud this leads 

 me to surmise that apospory in this instance is connected with, 

 and possibly the outcome of, apogamy. 



Professor Farlow, when he discovered that phenomenon, found 

 that Lastrea Pseudo-mas, var. cristata, was constantly apogamous, 

 i. e. was constantly produced from the prothallus by simple bud- 

 growth without the sexual interaction of the antheridia and 

 archegonia. That, it will be seen, is precisely the converse of this 

 case, where the sporophore bud3 out directly into the oophore. 

 Now 7 , assuming such an origin for the plant under notice, it 

 seems to me not at all surprising that, being thus produced by 

 simple bud-growth from a prothallus, it should be to a certain 

 extent unstable, and apt, if grown under specially close and 

 relaxing conditions of culture, as in this case, to revert to the 

 prothallic cell-formation from which it has so recently deviated 



2n2 



