DEVELOPMENT OF THE OSTRICH FERN. 37 



the fii'Ht, etc. On examining a plant at the end of the season, it >yill be found that not 

 only are the leaves for the following year plainly e\adent, but also those of the j^ear af- 

 ter. In a small plant that had only unfolded four leaves the previous summer, there were 

 easily seen fourteen young leaves in various stages of development, and this simply by 

 draAving back the outside ones. The outermost ones have the broad base of the petiole 

 almost completely formed in the autmnn, the frond being vei^ small and closely coiled. 

 It generally happens that some of these outer ones do not develop the frond at all. The 

 inner ones rapidly become smaller, and it is not easy to tell just how many are to develop 

 the next season. Indeed it sometimes happens that if the first set of fronds is prema- 

 turely destroyed, others may develop later that ordinarily would not have done so until 

 the following season. 



Each year there is found a circle of fronds which grow neai-ly upright, but the tips 

 bend slightly back, so that the group has the form of a deep vase, giving the jilant an 

 extremely elegant appearance. These fronds are all sterile and are ordinarily about one 

 metre in height, but may reach twice that, or even more. The frond is [)innate, the pin- 

 nae being deeply pinnatifid. It increases in breadth from the apex to a point below the 

 middle when it ])ecomes nai-rower tapering thence to the stipe, the lowest pinnae being 

 extremely reduced. The lobes of the pinnae are entire except in the first aerial leaves 

 that are produced by the stolons, in which the pinnae are not so crowded and the hjbes 

 broader in proportion and slightly dentate, recalling somewhat the earlier leaves of the 

 germ-plant. The lobes of the pinnae of the adult leaf are broadly lanceolate, the pinna 

 being cleft almost to its rachis, and each lobe is provided with a mid-rib, which usu- 

 ally forks at the apex and is provided on each side with from eight to ten simple veins 

 which extend to the margin. The hairs developed upon the young frond disappear, leav- 

 ing it almost completely glabrous. 



Specimens brought into the house in April, after remaining stationary for about tAVO 

 Aveeks, began to unfold their leaves and, in measuring one Aveek after, it Avas found that 

 they had reached a height of sixteen inches, so that it can be readily seen that the com- 

 ' plete unfolding of the leaf Avould take but a very few weeks. 



The fertile fronds begin to imfold al)out two months later, but their groAvth is sloAver, 

 the dcA^elopment of si^orangia l^eginuing A'er}^ earl}^ and neAV ones foi-ming up to the time 

 that the leaf is full groAvn. The fertile fronds are A'er}^ much smaller than the sterile, 

 and groAV rigidly upright among them, from tAA'O to six being ordinarily produced by each 

 plant annually. They seldom groAv more than one-half meti'e in height, and the piimae 

 are very much contracted, probably on account of the great draft made upon the frond 

 from the excessive production of sporangia. When mature they are dark, almost 1)hick- 

 ish green in color, and the margins of the pinnae so strongly revolute as entirely to con- 

 ceal the sporangia. The segments are scarcely separated in the young frond, but there 

 are constrictions betAveen them so that the pinnae have a beaded appearance. Each seg- 

 ment (PL 7, fig. 28) has but five A'eins, a mid-A^ein and four lateral ones, none of AAdaich 

 run completely to the margin. The upper half of the lobs is composed of but one layer 

 of cells, acting as an indusium. A transverse section of the young pinna (PI. 7, fig. 10) 

 shows that not only is the margin strongly revolute, but that it is folded on itself once, 

 and sometimes twice. Unlike the sterile leaves which decay in the autumn, the fertile 



