THE SPOROZOA 165 



These make their way into the body cavity, or lymph spaces, of the 

 mosquito, and ultimately find their way to the salivary glands, from 

 which they may be deposited, together with the salivary fluid, in the 

 blood of man (//). The life-history of a malaria organism thus involves 

 a complete change of hosts, one phase being in the warm blood of 

 man, the other a Coccidia-like stage in the Insecta, a group which 

 above all others is noted for the frequency and number of sporozoan 

 parasites. It is not improbable that a similar change of hosts occurs 

 in the parasites belonging to this same group of Haemosporidiida, 

 which have been observed in birds (Laveran, Labb£, '94); in reptiles 

 (Labbe, '94; Langmann, '99); and amphibia (Labbe, '94; Lang- 

 mann, '99); also it is possible that many of the uncertain forms, such 

 as Serumsporidiinn of the Crustacea (Pfeiffer, '95) or Lymphospo- 

 ridium of the trout (Calkins, '99), have a similar complicated life- 

 history. 



Apart from their pathogenic effects in man, the Sporozoa are 

 frequently a pest in the lower animals. The Sarcosporidiida have 

 already been mentioned as producing morbid symptoms resembling 

 Trichinosis, in the domestic animals often leading to death. The 

 Myxosporidiida occasion great loss to fish culturists by causing ulcers 

 which ultimately result in the death of the fish, and to silkworm cul- 

 turists on account of costly and extensive epidemics produced by 

 them among the silkworms. These organisms (Glugea bombycis) 

 were so disastrous to the silk industry during the years 1854-1867, 

 that a loss was estimated of at least 1,000,000,000 francs (about 

 $190,000,000). In regard, to this epidemic Huxley ('7°) writes: "In 

 the years following 1853 this malady broke out with such extreme 

 violence that, in 1858, the silk crop was reduced to a third of the 

 amount which it had reached in 1853 ; and, up till within the last year 

 or two, it has never attained half the yield of 1853. This means not 

 only that the great number of people engaged in silk growing are 

 some 30 millions sterling poorer than they might have been ; it means 

 not only that high prices have had to be paid for imported silkworm 

 eggs, and that, after investing his money in them, in paying for mul- 

 berry leaves and for attendance, the cultivator has constantly seen 

 his silkworms perish and himself plunged in ruin ; but it means that 

 the looms of Lyons have lacked employment, and that, for years, 

 enforced idleness and misery have been the portion of a vast popula- 

 tion which, in former days, was industrious and well to do." 



The caterpillars, although infested by the parasites which were 

 frequently so numerous that all of the organs of the body swarmed 

 with them, were nevertheless able to produce the moth. The 

 latter, though stunted and undeveloped, could lay eggs which them- 

 selves contained spores of the organism, and these spread the disease. 



