Sorosphaera Gram mis. 797 
In conclusion, my thanks are due to my sister, Miss Alice M. Schwartz, 
for her kind assistance in making the drawings. 
Summary. 
1. Sorosphaera Graminis is parasitic on the roots of various Grasses, 
though not the actual cause of the swellings sometimes found on them. 
2. S'. Graminis is closely allied to S'. Junci and S'. Veronicae } its life- 
history being similar in character. 
3. No hypertrophy takes place in the diseased roots, the disease being 
only detected after microscopical examination of the root. 
Bibliography. 
1. Maire and Tison (’ 09 ) : Cytologie des Plasmodiophoraceae. Annales Mycologici, 1909, 
vol. vii. 
2 . Blomfield and Schwartz (’ 10 ): Sorosphaera Veronicae. Annals of Botany, Jan., 1910. 
3 . Marchand (’ 10 ): Plasmodiophora Brassicae. Comptes rendus, tome cl, No. 21, p. 1348. 
4 . Nawaschin (’ 99 ): Plasmodiophora Brassicae. Flora, Band lxxxvi. 
5 . Schwartz (’ 10 ) : Sorosphaera Junci. Annals of Botany, July, 1910. 
EXPLANATION OF PLATE LXI. 
Illustrating the paper by Mr. Schwartz on the Life-history and Cytology of 
Sorosphaera Graminis. 
The drawings were made with the aid of the camera lucida. 
Fig. 1. Diseased plant of Poa Annua. Natural size. 
Fig. 2. Swellings on the roots. About twice natural size. 
Fig. 3. Transverse section of diseased root, x 512. 
Fig. 4. Transverse section of young diseased root, x 512. 
Fig. 5 (#, b , c } d). Various forms of amoebae. x 730. 
Fig. 6. Splitting of equatorial plate in vegetative nuclear division, x 1,300. 
Fig. 7. Dumb-bell stage of nuclear division taking place in a root-hair. x 1,100. 
Fig. 8. Cruciform stage of nuclear division, x 1,100. 
Fig. 9. Close of dumb-bell stage of nuclear division. x 1,100. 
Fig. 10. Formation of amoebulae. x 730. 
Figs. 11 and 12. Akaryote stage of organism, x 730. 
Fig. 13. Karyokinetic nuclear division in reproductive stage, x 730. 
Fig. 14. Various forms of sorospheres. x 512. 
Fig. 15. Early stage of disease in cortex of root. Longitudinal section, x 512. 
Fig. 16. Two amoebae making for a plant nucleus, x 730. 
Fig. 17. Karyokinesis of reproductive nuclei, x 512. 
Fig. 18. Amoebae round plant nucleus, x 730. 
Fig. 19. Completion of vegetative nuclear division, x i,too. 
Fig. 20. Cortex of root in late stage of disease, x 512. 
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