io66 Stevens .— On the Development of the 
is. The early cutinization of the exospore, which would make difficult 
the passage of materials through it, is in favour of the theory that the 
increase in thickness of this coat is the work of the tapetal plasmodium. 
13. While the exospore is thickening an endospore is laid down in 
contact with it, which gives the cellulose reaction with the triple stain. 
This coat is continuous excepting in front of the lines of cleavage in the 
exospore, so that the endospore would offer no resistance to the breaking 
apart of the spore-wall into the three flaps above spoken of. 
14. At first the spore protoplast lines the wall throughout; but after 
the endospore has been laid down, either its substance has been used up 
over the larger area of the wall, or it shrinks away from the wall and is 
found balled up at one end of the spore ; or the alternative remains that 
this condition is due to plasmolysis during the preparation of the materials. 
15. As the growth of the spores progresses the gradual depletion of the 
tapetal cytoplasm and nuclei is evidence that the substance of these has 
been diverted to the nutrition of the spores. 
16. Storage of food, largely in the form of starch, takes place in 
the sporangium wall and in the cells of the sorophore at the base of the 
sporangium. 
17. The tapetal plasmodium and the gonotokonts do not appear to 
contain stored food. 
18. Even sterile sporangia contain an abundance of stored food in their 
walls, and this suggests that their sterilization has been due to other causes 
than insufficient nutritive materials alone. 
Literature cited. 
Beer, Rudolf (’06) : On the Development of the Spores of Helm inthost achy s zeylanica. Ann. of 
Bot., xx, p. 181. 
Bierberg, W. (’08): Die Bedeutung der Protoplasmarotation fur den Stofiftransport in den Pflanzen. 
Flora, Bd. xcix, H. 1, p. 52. 
Bin ford, R. (’ 07 ) : Development of the Sporangium of Lygodium. Bot. Gaz., xliv, p. 214. 
Bower, F. O. (’96) : Studies in the Morphology of Spore-producing Members, II. 
Burlingame, L. L. (’ 09 ) : The Sporangium of the Ophioglossales. Bot. Gaz., xliv, p. 41. 
Campbell, D. H. (’05) : Mosses and Ferns, p. 270. 
Fitting, Hans (’00): Bau und Entwickelungsgeschichte der Makrosporen von Isoeles und Sela- 
ginella. Bot. Zeit., Jahrg. lviii, p. 107. 
Lotsy, J. P. (’04) : Die Wendung der Dyaden beim Reifen der Tiereier als Stiitze fur die Bivalenz 
der Chromosomen nach der numerischen Reduktion. Flora, Bd. xciii, p. 69. 
Lyon, Florence (’05): The Spore Coats of Selaginella. Bot. Gaz., xl, p. 285. 
Pfeffer, W. (’97) : Lehrbuch der Pflanzenphysiologie, Bd. i, p. 602. 
Prantl, K. (’81) : Untersuchung zur Morphologie der Gefasskryptogamen. 
Strasburger, E. (’82) : Ueber den Bau und das Wachsthum der Zellhaute. 
- (’89): Ueber das Wachsthum vegetabilischer Zellhaute. Histologische Bei- 
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