XVI Journal of Agricultural Research voi. v 



Page 



Plate LXVIII. Embryology of Aphis point: Fig. i. — Fertilized egg previous 

 to formation of blastoderm. Fig. 2. — Fertilized egg showing formation of 

 blastoderm. Fig. 3. — Unfertilized egg. Fig. 4. — Polar organ. Fig. 5. — 

 Conditions of embryo and polar organ at commencement of revolution. 

 Fig. 6. — Yolk cell. Fig. 7. — Germ cell 994 



Plate LXIX. Embryology of Aphis pomi: Fig. i. — Ovarian yolk before divi- 

 sion. Fig. 2. — Half of ovarian yolk shortly after " dumb-bell " formation . 994 



Plate LXX. Embryology of Aphis pomi: Fig. i. — Half of ovarian yolk, end 



chambers forming. Fig. 2. — Half of ovarian yolk, end chambers formed. . 994 



Plate LXXI. 'Emhryolo^ oi Aphis pomi: Fig. i. — Half of ovarian yolk, egg 

 chambers forming. Fig. 2. — Thickening serosa accompanied by cells of 

 polar organ 994 



Plate LXXII. Embryology of Aphis pomi: Fig. i. — Invagination of dorsal 



body. Fig. 2. — Dorsal body completely formed 994 



Plate LXXIII. Embryology of Aphis pomi: Emerging nymph, showing egg 



biu-ster •. 994 



Plate LXXIV. Structural details of Aphis pomi, A. avenae, and A. malifoliae: 

 Fig. 1. — Aphis pomi: Antenna of wingless viviparous female, adult. Fig. 

 2. — A . pomi: Antenna of wingless viviparous female, third instar. Fig. 3. — 

 A. pomi: Antenna of wingless viviparous female, second instar. Fig. 4. — 

 A. pomi: Antenna of wingless viviparous female, first instar. Fig. 5. — 

 A. pomi: Antenna of stem mother. Fig. 6. — A. pomi: Antenna of inter- 

 mediate. Fig. 7. — A. pomi: Antenna of winged viviparous female. Fig. 

 8. — A. pomi: Male genitalia. Fig. 9. — A. pomi: Antenna of male. Fig. 

 10. — A. pomi: Antenna of wingless viviparous female, fourth instar. Fig. 

 II. — A. pomi: Cornicle of winged viviparous female. Fig. 12. — A. pomi: 

 Cornicle of wingless viviparous female. Fig. 13. — A. pomi: Cornicle of 

 male. Fig. 14. — A. potni: Cornicle of oviparous female. Fig. 15. — A. 

 avenae: Antenna of stem mother, first instar. Fig. 16. — A . pomi: Antenna 

 of stem mother, first instar. Fig. 17. — A. malifoliae: Cornicle of winged 

 viviparous female. Fig. 18. — A. avenae: Cornicle of winged viviparous 

 female. Fig. 19. — A. pomi: Cauda of adult. Fig. 20. — A. pomi: Hind 

 tibia of oviparous female. Fig. 21. — A. pomi: Cauda of pupa 994 



Plate LXXV. Aphis poyni on its host plant: Fig. i. — Colonies on apple. Fig. 



2. — Apple twig bearing eggs 994 



SoiLSTAiN, OR Scurf, of the Sweet Potato 



Plate LXXVI. Fig. i. — Petri dish containing a pure culture of Monilochaetes 

 infuscans. Fig. 2. — a, Part of a conidiophore of M. infuscans, showing the 

 unbroken chain of conidia; h, d, and k, various ways of the breaking up of 

 the chains of conidia when disturbed or moistened; c, e, f, g, k, and j, 

 spores collecting in pockets after the chains of conidia have broken up; i, 

 bending in of the chain of conidia prior to breaking up into individual 

 spores 1002 



Plate LXXVII. c, Part of a cross section of a sweet-potato root, showing the 

 relationship of Monilochaetes infuscans to the epidermis of the host; b, 

 germination of a fragment of mycelium of M. infuscans, showing the germ 

 tube which is first produced and upon which conidia are borne; c, d, e,f, 

 g, h, i, and t, different stages in the development of the spore and the 

 chain of conidia; 0, j, k, and p, protruding hyaline tube at the tip of the 

 conidiophore on which are borne the conidia; /, n, and w, diflferentiation 

 of the coarser dark mycelium, and the finer hyaline to subhyaline hyphae; 

 u, attachment of the conidiophore to the mycelium; r, conidiophore-bear- 

 ing mycelium, being part of u; m, q, s, v, x, y, and z, different stages in the 

 germination of the conidia of M. infuscans 1002 



