162 



Mycologia 



until the conidium has reached maturity. However, conidia pro- 

 duced subsequently to the second, cannot be regarded as endo- 

 conidia, for while they are formed within a sheath, this sheath is 

 open at the tip. In true endospore formation, the spores are 

 delimited within a closed cell, although the spore walls may not 

 develop until after escape of the spore masses. 



It is apparent that the olive conidia are not endospores. They 

 are formed by the swelling of the protoplast beyond the opening 

 at the tip of the conidiophore and are not separated from the 

 protoplast until the conidium has reached mature size. 



Summary 



1. A study has been made of the formation of the hyaline and the olive- 

 brown conidia of Sphaeronema fimbriatum. 



2. Contrary to Brierley's anticipations, the process of conidial formation 

 in Sphaeronema differs in certain particulars from that in Thielavia. 



3. In the formation of the first conidium, the distal end of the protoplast 

 of the conidiophore invests itself with a new wall and separates as a conidium. 



4. This conidium is liberated by dissolution of the tip of the conidiophore. 



5. Often a second conidium is formed in the same manner as the first and 

 before dissolution of the tip of the conidiophore. 



6. The first two conidia should be regarded as endoconidia. 



7. Conidia produced subsequently to the second are not endoconidia. 



8. Olive-brown conidia are not produced endosporously. 

 State College, 



West Raleigh, N. C. 



References Cited 



1. Halsted, Byron D., and Fairchild, D. G. Sweet Potato Black Rot. Jour. 



Mycol., V. 7, No. 1, pp. 1— 11, pis. 1-3. 1891. 



2. Taubenhaus, J. J. The Black Rots of the Sweet Potato. Phytopath., V. 



3, pp. 159-161. 1913. 



3. Zopf, W. Uber die Wurzelbaume der Lupinen, eine neue Pilzkrankheit. 



Zeitschr. f. Pflanzenk., V. 1, pp. 72-76, fig. 1. 1891. 



4. Brierley, William B. The " Endoconidia " of Thielavia basicola. Zopf. 



Ann. Bot., V. 29, No. 116, pp. 483-493, figs. 1-12, pi. 23. 1915. 



5. Gilbert, W. W. The Root-rot of Tobacco Caused by Thielavia basicola. 



U. S. Dept. Agr. Bur. Plant Indus. Bui. 158, pp. 12 and 13. 1909. 



Explanation of Plate 7 



All the drawings were outlined and as many as possible of the details put 

 in with the aid of a camera lucida. A different magnification was used for each 

 of the following groups of figures: r; 2, 13; 3-7, 14-17; 8-12. The reduced 

 magnification can easily be calculated from the scale given with each group. 



