1903] LYON—THE SPORE COATS OF SELAGINELLA 201 
from the sporangium.” . I have come to believe, however, that where 
actual gaps occur they are due to shrinkage and the dissolution wholly 
or in part of the intervening substance, and that the appearance of 
separation in the living spore can be explained by the different density 
of the concentric layers. In material showing no shrinkage elsewhere, 
I found that these regions were not empty, but completely filled with 
matter closely resembling the spore membrane at different periods 
of its transformation into coats. 
It must be understood that the entire substance of the spore out- 
side of the protoplast is a viscous mass of the consistency of thin 
syrup, in which two regions are becoming not.only different in their 
physical but also in their chemical natures. This substance retains 
a plastic condition until the spore has attained its full size and the 
‘wo coats their entire bulk. Then follow the changes which. result 
in their hard horny or woody character. Into the viscid mass are 
passing solutions from the sporangium. ‘The direct physical effect 
upon this mass as a whole would be a tendency to increase in diameter 
and bulk; but apparently all regions do not swell alike, the more 
sistant regions where coats are forming become drawn apart, 
ang between them a stretched area of less dense nature, very 
tasily dissolved by reagents, subject to great shrinkage and liable to 
be ‘orn and not readily stained. From material fixed in bichromate 
of Potassium and exposed to light, the gelatinous nature of the sub- 
sey In these regions was clearly demonstrated. They always 
n like the undifferentiated part of the spore membrane, Firr1ne 
also remarks that “‘sie verhalten sich bei allen Arten gegeniiber Ren- 
sentien wie die Special Mutterzellmembranen.” 
There seem to be three possibilities: (1) Firtrne’s view that the 
nee between protoplast and under coat, and between inner and 
eo zwischen den Hauten und zwischen dem Mesospor und 
ikrotom oe ealapsaie Sporen ganz: hyalin. . a An fixirtem und = on 
Entwickelungsstadium * aterial sind in ihnen Gerinnungsmassen, = ae 
der Meaheiscs ca a Menge, vorhanden. enn die 
die Hohlriume a © begonnen hat, ist von ihnen noch nichts zu a 
hier und da netzartig ‘alla eworden sind, werden in ihnen aise se" PN 
ene sichtbar die wahrend der Vergrésserung der spore 
Schnell : 
“srmehrt werden. In noch dlteren Stadien bilden sie . . . . sowohl zwischen 
r ‘ : . 
und Mesospor, wie auch zwischen diesem und der Plasmablase je eine hyaline, 
s durchsichtige Masse, die die beiden Riume meist nicht vollstindig ausfillt.” 
