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TABLE 2. Sunlmary of cross infection experiments reported in this aird a previous paper(2). Haemoproteus Haemoproteus columbae palum bis -Goluniba livia + canariensis + + + Columba palurnbus avicularia 2 + Psecdolynchia Ornithomyia + = Infection. -= No infection. f = Partial devclopmcnt (possibly coniplete in some).flies had sporozoites in its salivary glands, but 2 had survived for only 7-12 days after their infective feed; of the remainder, 2 had survived for 10-14 days, one for 12-16 days and one for 15-19 days. DISCUSSIONsites is less complete. H . palumbis completes sporogony in P. canariensis, the vector of H . coZumbae(2), and the latter haemoproteid is able at least to commence development in 0. avicularia, the vector of the former. H . columbae completes sparogony in about 10 days in its natural vector(l,4) and succeeds in completing development in only about 12% of ,the flies(4); therefore, since only 4 0. avicularia were known to have survived for 10 or more days after being placed on an infected bird, it is impossible to draw a firm conclusion from the fact that none of these flies had sporomites in its salivary glands when dissected. However, the evidence indicates that 0. avicularia is a less satisfactory host for H . columbae than it is for H . palumbis, which completes sporogony in about 87% of experimentally infected flies (2). I repeat my thanks to Mr. E. J. Blackie and his staff, to Dr. Helmy Mohammed and other members of the Department of Zoology, Ain Shams University, Cairo, and to Dr. Murton, Mr. Isaacson and Mr. Hancock for their help(2). REFERENCES Bi;,zz: ~~n~:~Z I ' i~~~~-~.~Q n Y of Haemo@otem d u m b 4 e . indet. of the wood pigeon Columba p . palurnbus. J . Protozool. 13, These results, together with those previously reported for H . palumbis( 2 ) , are summarized in Table 2 . They show restriction as far as their vertebrate hosts are concerned. that the haemoproteids Of Columba have strict host 2. Baker, J. R. 1966a. The host-restriction of Haemoproteus yp. Whether this is due to inability of the spmvwites to develop into mature schizonts, or Whether sue xhiZ%ony occurs but [the resulting merozoites are unable to invade erythrocytes and develop into gametocytes, is unknown. In the invertebrate hosts, host restriction of these 2 para-y:8. 1966b. Haemoproteus pdumbi. nov. (SPOrOZOa, Haemosporina) d the English wood-pigeon Collrmba p . palurnbus. J . Protozool. 13, 515-9. 4. Mohammed, A.H.H. 1958. Systemotic and experimental studies on protozoal blood parasites of Egyptian birds, 2. Cairo University Press.

SYNOPSIS. Euglena gracilis strain Z rendered permanently apochlorotic by several chemical and physical agents contains bodies similar in size to normal plastids. Some of these bodies contain lamella‐like structures; others contain crista‐like structures. The lamella‐ and crista‐like structures are made up of 2 electron‐dense layers separated by an electron‐lucent layer. These structures are compared to normal lamellae and it is suggested that apochlorotic cells contain lamellae that lack the thicker, inner electron‐dense layer, or more likely, that the apochlorotic condition prevents two discs from fusing to produce the thicker inner electron‐dense layer which contains the photosynthetic pigments.