62 



MORPHOLOGY OF ANGIOSPERMS 



The archesporial cells behave as do those of the mierospo- 

 rangrum, and in case the archesporiimi is a plate of cells, the 

 resemblance is striking. In the large majority of cases, how- 

 ever, the archesporiimi is a single cell, and often by transverse 

 division it gives rise to a primary parietal cell and a primary 

 sporogenons cell (Fig. 26). That the former cell, or plate of 

 cells, as it is in the case of a several-celled archesporiimi, repre- 

 sents the primary parietal layer of the microsporangiimi seems 



clear. In recognition of this fact 

 Strasburger called it the " tapetal 

 cell," but for reasons given under 

 the microsporangiimi we shall call it 

 the parietal cell— that is, a cell that 

 develops in part the wall of the em- 

 bedded sporangium. Mottier 25 has 

 reported a very peculiar case in Ari- 

 saema, in which the single archespo- 

 rial cell divides by anticlinal walls 

 into three or four cells, each of which 

 then cuts off a parietal cell. Just 

 how 7 far this is exceptional behavior 



B 



Fig. 26. — Salix glaucophylla. Lon- 



remains to be seen, but it intro- 

 duces an interesting problem as to 

 the application of the term archespo- 

 riimi. 



The behavior of the primary 

 gitudinai sections of nuceiius, par i e t a l cell is exceedingly varied. 



x 631. A, single hypodermal . _ . - 



archesporial cell (a). B, arche- A] 

 sporial cell has given rise to pri- 

 mary parietal cell (t) and pri- 

 mary sporogenous cell (m). — 

 After Chamberlain. 36 



periclinal divisions to occur, result- 

 ing in a long row of parietal cells, 

 corresponding to the parietal layers 

 of the microsporangiimi. In case 

 there is a plate of archesporial cells the radial rows of parietal 

 cells are very conspicuous, as in the Rosaceae and many of the 

 Amentiferae (Figs. 23, B, D, E). In other cases the parietal 

 rows become lost by the formation of anticlinal walls. If 

 the mother-cell broadens rapidly, the first divisions of the pri- 

 mary parietal cell may be anticlinal, followed by periclinal 

 divisions, as in Ruta graveolens (Guignard 17 ) and Potamoge- 

 ion foliosus (Wiegand 54 ). The deep-placing of the sporoge- 



