1898] BRIEFER ARTICLES 127 
sacs ready for fertilization. It hardly seems probable that a macro- 
sporangium would pass the winter in this stage. : 
SaLix.—Two years ago I studied a very complete series of micro- 
sporangia and macrosporangia in Salix‘ ‘This series, containing 
sporangia collected in nearly every month of the year, showed that the 
microsporangia pass the winter in the spore mother cell stage. The 
midwinter pistillate flowers showed considerable variation; in some 
even the rudiment of the nucellus could not be distinguished, while in 
others the archesporium may have been present. Undoubted macro- 
spore mother cells were not found until growth had been resumed in 
the spring. 
PopuLus.—This genus shows practically the same conditions. 
Staminate flowers of P. montilifera Ait. collected in July showed the 
primary sporogenous cell. In October the sporangia had reached the 
spore mother cell stage, and could hardly be distinguished from the 
midwinter condition represented in fg. 7. No undoubted macrospore 
mother cells were found until growth had been resumed in the spring. 
Corvus AMERICANA Walt.— Midwinter catkins showed the pollen 
grains apparently ready to be shed. The division into the tube 
nucleus and generative nucleus had already taken place (jg. 8). 
ALNus GLUTINOSA Willd.—This species showed about the same 
conditions as the last. The winter microsporangia appear so nearly 
like those collected just before the shedding of pollen in the spring 
that one figure might represent them both (fg. 9). 
These examples are sufficient to show that sporangia of various 
Plants pass the winter in very different stages of development, and it 
seems probable that all plants of a given species in a given locality 
Pass the winter in about the same stage of development. 
noo mother cell seems to be a very usual halting place in the 
chek i of sporangia, but whether this is pecaUSe the spore 
uses, Is better able to withstand unfavorable congrt ope, or for 
here rife it is at present impossible to decide. It has been 
of dint, eee that the spore mother cell, in which the reduction 
de nae «ee takes place, requires a longer resting period than = 
Where the pescede or follow it. This may be seen even in annua : 
ih thoes . > ang period is comparatively short, and is easily observe 
ae Pabchate and perennials which pass through all Btagre from 
eth dealer to seed in a single season. It is certain, however, 
lutions to the life history of Salix. Bot. GAz. 23: 147-178. 1897. 
