PLATE 58 



Cronaritium rib kola: 



A. — The elements of the pycnium. The cells at the base are almost empty. Above 

 them are the short branching trunks which bear the sporophores. a, A sporophore; 



b, pycniospores in sectional view; c, the cytoplasm is constricted just beneath the 

 spore; d, the nucleus is dividing. X 1,700. 



B. — An active thin-walled haustorium from a pine host cell. X 1,700. 



C, D, E. — Old haustoria. C and D have basal cuplike sheaths and tip sheaths. 

 E is completely inclosed in a thick sheath. X 850. 



F. — Telophase of division of one of the cells of the fertile layer to form a sterile 

 cell. X 1,700. 



G. — A newly formed sterile cell. X 1,700. 



H. — A large polarized nucleus from the fertile layer. X 1,700. 



I. — An aecial basal cell resulting from the fusion of two adjacent cells of the fertile 

 layer. Compare the size of the nuclei with that of the nucleus shown in PI. 57, II. 



X 1,700- 

 J. — A diagram of a basal cell resulting from the fusion of two cells from different 



levels. X 85c. 



K. — A diagram of a trinculeate irregular basal cell from the tip of which a tri. 

 nucleate aeciospore initial has been cut off. X 850. 



L. — A diagram of part of an irregular compound fusion cell. X 850. 



M. — A basal cell with the nuclei in early prophase. The centrosome in the left 

 nucleus has apparently divided, b. An aeciospore initial cell with the nuclei in 

 midanaphase. X 1,700. 



N. — Part of a basal cell. The nuclei in prophase. X 1,700. 



O. — A later stage than the preceding. The spindle and centrosomes are just visible 

 in the upper nucleus. X 1,700 



P. — Metaphase of the division in the basal cell. A centrosome is evident at each 

 of the poles of the spindles. The chromatin is condensed into chromosomes. The 

 nucleoli have moved off and begun to fade. X 1,700. 



Q. — ^ Early anaphase, a little later than the stage in figure P. X 850. 



R. — Midanaphase of the division. The chromosomes are moving toward the poles 

 along the outside of the spindle. X 1,700. 



S. — A later stage of anaphase than in figure R. X 1700. 



T. — Final anaphase. The chromatin is condensing in two groups at each pole. X 

 1,700. 



U. — Telophase. The two groups for each pole are still distinct. X 1,700. 



V. — Telophase. The two groups at each pole have condensed to single masses. 

 The wall which will separate the aeciospore initial from the basal is beginning to 

 form at a. X 1,700. 



W. — 'Prophase of the division in the aeciospore initial. X 1,700. 



X. — Final telophase of the same. X 1,700. 



Y. — ^An aeciospore chain in section view, a, The basal cell; b, an aeciospore initial, 



c, an intercalary cell; d, a young aeciospore. The nuclei in the upper intercalary cells 

 are degenerating. X 850. 



Z. — A large mature aeciospore in surface view. X 850. 

 AA. — A nucleus from a mature aeciospore. X 1,700. 



