292 BOTANICAL GAZETTE [ocToBER 
outer coat, are spaces filled with a solution—comparable to a vacuole; 
(2) that possibly there are protoplasmic connections between the 
protoplast and the two coats, and that the intervening substance is 
protoplasm, penetrating the endospore and extending to the exospore; 
(3) the suggestion, made above, that normally there are no clefts in 
the spore, but that the matter outside of the protoplast is to be 
regarded as an envelop of gelatinous matter in process of local trans- 
formation into concentric layers of different physical ‘nature, and 
at the same time increasing enormously in size by the imbibition of 
matter from the sporangium. Much time was expended in trying 
to demonstrate protoplasmic continuity through the coats but with- 
out success. 
The third view grows convincing, as it is possible to obtain sec 
tions which show the spores to be a solid mass without spaces, the 
regions of the developing coats not being sharply marked off from 
the substances that Firrinc regards as foreign matter, and that I 
believe to be merely stretched areas of the gelatinous membrane out of 
which the spore coats are differentiating. Indirect evidence is 
afforded by the growth of the coats in S. rupestris in which there 1s 
at no time any suggestion of “spaces filled with nutrient solutions.” 
The further development of the megaspore consists in the expan 
sion of the protoplast which soon overtakes the endospore, which 1 
turn is carried along and stretched against the exospore. ate 
portion of the exospore in contact with the endospore (fig. 18) usually 
fails to coalesce completely with the outer part (figs. 18 and 19); 
and if one has failed to follow its behavior closely might readily be 
interpreted as an intermediate distinct coat. This account fails to 
agree with Frrrmnc’s and CampBELi’s.3 The two coals I have 
shown in figs. 17-19 they call exospore and mesospore- ‘The a 
spore they describe as arising de novo after the protoplast — 
expanded, and in contact with it, thus making three distinct coats: 
In the species which I have investigated—S. rupesiris, Ae 
Emmeliana, S. densa, S. cinerascens, and two unnamed sper, not 
Jamaica—I can demonstrate only two distinct coats. iy it 
be possible that others have made the same error tha 
3 CAMPBELL, D. H., Studies in the gametophyte of Selaginella. 
16: 419-4 8. pl. 19. 1902. 
