Harper. — Cell-Division in Sporangia and Asci. 493 
by Cohn \ and the whole process, as noted above, has been 
described and figured by Brefeld, so I need only mention 
the more especial points bearing on spore-formation. The 
mycelium of Pilobolus is one-celled and multinucleate, and 
when the sporangiophores are to be formed, the protoplasm 
collects at certain points in the mycelium, producing barrel- 
shaped swellings. These swollen portions are cut off by 
both peripheral and proximal walls. The division of the 
protoplasm is accomplished by simple constriction-furrows, 
and in the bulb so formed, as noted above, a rapid multipli- 
cation of nuclei takes place 1 2 . This dividing period probably 
corresponds to the dividing period in Synchitrium , whereby 
the one nucleated cell becomes multinucleated. The proto- 
plasm of Pilobolus is already multinucleate, but preparatory 
to reproduction these vegetative nuclei multiply rapidly, 
apparently simply as a preparation, for the production of 
a sufficient number of spores. The protoplasm in the bulbs 
becomes much more densely packed with nuclei than that 
in the adjacent vegetative portions of the mycelium. This 
period of division is completed before the budding out of the 
sporangiophores. I have never observed nuclear division 
going on in the growing tip of the sporangiophore nor in the 
young sporangium before the cutting off of the columella. 
The growth of the sporangiophore is apparently largely 
accomplished by the flowing out of the material stored up 
in the bulb. As the sporangium becomes larger the bulb 
is more and more emptied of its protoplasmic contents, though 
a layer sufficient for maintaining the turgor of the central 
vacuole is always maintained, and in this layer also numerous 
nuclei are present. The sporangiophore grows in length, and 
is bright yellow throughout its upper portion, due to the 
presence of yellowish, perhaps fatty, granules in the proto- 
plasm. At first it is slightly narrowed at the tip, but after 
1 “ Die Entwicklungsgeschichte des Pilobolus crystallinus.” Nova Acta Acad. 
Caes. Leop. Carol. Nat. Cur., vol. xviii, pt. i. 
2 A detailed description of these and some other nuclear divisions in the fungi 
I expect to give in the near future in another connexion. 
