Biological Papers. 75 



•erative sperm-cell which comes to it within a pollen-tube through the micro- 

 pyle, or sacred door (through which nothing else enters), along a specially 

 prepared path, from an androphyl in a staminate or a perfect flower of its 

 own kind ; and thus a new being is created. This is the embryotic 

 period; and is the most important of all, though least (microscopic, in 

 fact), and is least understood as to its inmost workings. 



Second. A formative stage, during which all the parts of the future 

 plant are created, assembled, and fully organized in embryo. This is the 

 SEED-FORMING PERIOD in carpellates ; it corresponds to the oosporal stage 

 in archegoniates and with the egg stage in all animate creation. In all 

 short-lived carpellates, such as annuals and biennials (or winter annuals), 

 creation is determinate. All parts of the plant, except the reproductive 

 bodies, are completely created and fully organized before ever the plant 

 leaves the wall of the seed. In trees and perennials of temperate and cold 

 regions growth is determinate. One complete year's growth is organized 

 in the seed; afterward, each year's growth is organized in the bud, usually 

 during the latter part of the year preceding development. Flowers and 

 fruit are organized at the same time. 



Third. A development stage, during which the plant, having become 

 established as an independent existence, grows and develops to its full 

 stature, so far as circumstances will permit. This is the period of 

 GROWTH ; and is the most evident stage in all carpellates and in nearly all 

 plants. It corresponds with the sporophytic stage in archegoniates, with 

 the larval stage in insects, and with the young period in all animal life. 

 Even in carpellates the plant during this period is called sporophyte. To- 

 ward its close the reproductive bodies are created, organized, and developed, 

 and the gametophytes organized. 



Fourth. An executive stage, during which the plant performs all the 

 functions for which it was created: blossoms, bears fruit, and does its part 

 toward the reproduction of other plants of its kind. This is the fruit- 

 bearing period, and corresponds to the gametophytic stage in archegoniates 

 and to the adult period in all creation. While in archegoniates the oospore 

 when formed is separated from the sporophyte and develops as a separate 

 existence, in carpellates it is not so. In this subkingdom the oospore is re- 

 tained within the body of the ovule; here the prothallia are formed contain- 

 ing the true sexual organs, the archegonia and antheridia, and here the 

 gametophyte is fully developed, always within the wall of the seed which 

 carries it. This whole operation is hidden within the wall of the seed; and 

 so also in anthophytes is the seed hidden within the walls of the ovulary. 

 This last period covers completely and includes the embryotic stage and the 

 constructive portion of the seed stage of a future generation. 



There are three main phyla of this subkingdom: (i) Palm-like and fern- 

 like plants, in which the ovules are always uncovered, as in cycadophytes; 

 (ii) plants without perianth, in which the ovules are at first uncovered, and 

 later are partially covered by a scale, as in strobilophytes; (Hi) plants with 

 conspicuous perianth, in which the ovules are always completely concealed, 

 as in anthophytes. 



