



B 





)-.;: : 









e 







H 



Fig. 7. — Pilobolus crystallinus. Cytology of the sporangivim. A, median longi- 

 tudinal section of a sporangiophore bearing a yoiuig sporangium ; the cyto- 

 plasm is vacuolated and contains numerous nuclei, n, shown as dots. B, median 

 section of an older sporangimn showing the course of protoplasmic flow from 

 the mouth of the sporangiophore ; protoplasm highly vacuolated and containing 

 many nuclei, n. C, section of sporangial wall it' and spore-plasma p just before 

 cleavage begins ; n, the nuclei. D, median section of a sporangium at a stage 

 when the columella is forming, showing cleavage furrows c c at the base and 

 flattened vacuoles v above ; /(, the nuclei ; small rounded vacuoles throughout 

 the cytoplasm. E, section of spore-plasma e from base of sporangium during 

 cleavage, showing : a, the sporangial wall ; b, the gelatinous collar ; c, the 

 columella-cleft between thecoKnnella and the spore-plasma; d, tlie protoplasmic 

 lining of the columella ; c, the s[)ore-plasma undergoing cleavage to form pro- 

 tospores ; /, superficial cleavage furrows ; g, an angular vacuole of the spore- 

 plasma ; h, nuclei. F, section through upper part of a sporangium showing 

 sporangial wall w and irregular sausage-shapeil bodies *• formed by cleavage of 

 the spore-plasma, a little older than E. G, similar to F but older, showing 

 uninucleate protospores p formed by cleavage of the spore-plasma ; «', spo- 

 rangial wall. H, protospores p witli dividing nuclei, young daughter nuclei 

 connected by remains of spindle fibrils ; o, gelatinous collar ; b, protoplasm of 

 columella. Magnification : A, B, D, not stated ; C, S"J4 ; E-H, 500. Copied 

 by tlie author from R. Harper's CcU-Diri.sioii in Sporaiiijia and Asci {Annuls of 

 Botany, Vol. XIII, 1899, Plates XXIV and XXV). 



