248 SPOROZOA. 



malarial parasities of the genus Laverania and Plasmodium, 

 Blood-parasities of birds and reptiles. 



Remarks. — Celli and San Felice (1891) reported three kinds 

 of malarial parasites in birds, but these were not described 

 sufficiently adequately to be recognizable. Till 1927 the 

 organisms continued to be considered as belonging to a single 

 species, usualty called Plasmodium, precox. Hartmann (1927 6), 

 however, beheves that at least three species exist. For one 

 of these, isolated from " Whitmore " strain, he retains the 

 name P. prsecox ; the second, known as " Hartmann " strain, 

 he named P. cathemerium ; and the third strain, obtained by 

 Huff in Virginia, was named P. inconstans. Evidence has 

 been secured by Manwell (1929) that the " Whitmore " strain 

 may consist of two distinct varieties or species. He seems 

 to have estabhshed that the " Whitmore " strain of malaria, 

 originally isolated by Whitmore from a New York sparrow 

 in 1913, is a variety of P. inconstans, and is distinct from 

 P. prsecox, which was isolated by Huff in 1926 from canaries 

 originally infected T\dth the " Whitmore " strain. Ed. and 

 Et. Sergent and Catanei (1929) described another species 

 from Algerian birds as P. rouxi, and Huff (1930) yet another 

 as P. elongatum from canary and sparrow from the United 

 States of America. Manwell (1930) regards P. cathemerium 

 Hartmann and P. elongatum Huff as valid species, and 

 P. inconstans Hartmann, the " Whitmore " strain, and the 

 " German " strain as three strains or varieties of P. prsecox. 

 Thus according to him there are three species, namely, P. prse- 

 cox, P. cathemerium, and P. elongatum. These three species 

 differ from one another in morphology, length of incubation 

 period, size of oocysts produced in the mosquito, length of 

 asexual cycle, etc. The morphological differences chiefly 

 concern the gametocytes. Those of P. prsecox are more or 

 less round, displace the nucleus of the host-cell, and contain 

 fine dust-like particles of pigment. The gametocytes of 

 P. cathemerium are similar in shape and size, but contain much 

 coarser granules of pigment, which tend to have a rod-like 

 shape. P. elongatum takes its name from the elongate 

 character of the gametocytes, which markedly resemble 

 those of Hsemoproteus. Russell (1932) described another 

 species. Besides these species, which have been employed 

 in experimental work, a large number of other species of 

 Proteosoma have been described as distinct, because they 

 are found in different species of birds. It is now no longer 

 possible to regard the malarial parasites of birds as all belonging 

 to the single species P. prsecox ; but the opposite tendency 

 towards the multiphcation of species should be avoided 

 unless definite morphological distinctions are noted. In 

 recent years Ed. and Et. Sergent and Catanei (1931) and 

 Giovannola (1934) have attempted a systematic revision of 



