1902] CURRENT LITERATURE 165 
0, ROSENBERG,’ in investigating the pollen of Zostera marina, finds that 
the radially elongated archesporial cells give rise to tapetum on both sides 
of the sporangium by cutting off isodiametric cells at each end, Some of the 
sporogenous cells form sterile tissue. This is nourishing in nature and 
: slater Empeerented only by Hive nuclei between the spore mother cells, The 
tined to form microspores divide many times 
ve a walls 7 a linear pollen mother cells. The tetrad divi- 
‘ions following are also longitudinal, and the second occur before the walls of 
the first reach the ends of the cells. The nature of these divisions is evidenced 
by their rapid succession and by the reduction of chromosomes from twelve 
six. The remarkable thread- like form of the pollen (2000 by 8 when 
mature) prevents the formation of the typical Be group, the microspores 
simply adhering in bundles. The solution of t e microspore problem in 
is of special interest to morphologists since it clears away the last 
reported case of the formation of microspores from mother cells without the 
mince division —T. C. Frve. 
_ Netumso is certainly a perplexing form. The closed bundles, irregu-— 
| Scattered, Present a distinctly monocotyl feature; the leaves with 
Suggest dicotyls, while the flowers might be either : : 
The earlier observers, dealing with mature se - 
the embryos of A’e/umbo and of other members of the 
eae as dicotyledonous. The recent work of Mr. H. L. Lyon? — 
seeks to ‘establish their monocotyledonous character. Material for comets — : 
ies cil was Sorte in August, 1899, and sivogai 1095 in a noe 
cotyledon now becomes bilobed by ; he 
Btn The on of © 
. ae ‘sua leaf arises on the side opposite the cleo. 
Paper as dea ish th op : of the € embryo Hee 
— J oe 
lung von Zostera, Medel. Stockbolms | a 
[Observations on the oe vee 2 on . 
