Malaria / by William H. Welch and William S. Thayer.

  • Welch, William Henry, 1850-1934.
Date:
[1897]
Catalogue details

Licence: Public Domain Mark

Credit: Malaria / by William H. Welch and William S. Thayer. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

    14/152 (page 26)
    reduced to a narrow pale rim, bursts and the spores are set free, or the corpuscle may have disappeared before the process of segmentation is completed. The pigment remains behind, and is quickly engulfed by phagocytes. Sometimes in the sestivo-autumnal variety segmentation occurs in organisms entirely devoid of pigment. These segmenting bodies are called also sporulating forms. The free spores speedily invade fresh red blood-corpuscles, where, as the small, colorless, amoeboid, hyaline bodies already mentioned, they begin again the cycle of development. The direct transformation of the motionless ^ round spores into the small, hyaline, amoeboid bodies has been very rarely observed, but there is no reason to suppose that there exists any stage intervening between these two forms. In the complete sporulating cycle of development which has been described we can distinguish, therefore, the following forms of the para- site : (1) unpigmented, amoeboid, hyaline bodies; (2) pigmented, amoe- boid, hyaline bodies; (3) full-grown or adult bodies; (4) presegmenting bodies; (5) segmenting or sporulating bodies; and (6) spores. All of these various bodies are depicted in Plates I. and II. As already mentioned, in the sestivo-autumnal variety this cycle may be completed without the appearance of pigment. These bodies are to be thought of, not as separate and distinct forms, but simply as successive stages of development with all transitions from the youngest to the most advanced. Especially can no sharp distinction be drawn between bodies (1) and (2) and between bodies (3) and (4). The recog- nition, as a distinct form, of the body designated as presegmenting is of less practical importance for the quartan and tertian varieties than for the sestivo-autumnal. The name plasmodium was applied by Marchiafava and Celli originally to the unpigmented, amoeboid forms. It is frequently em- ployed to designate both the pigmented and the unpigmented amoeboid bodies, as well as the parasite in all of its forms. These amoeboid bodies may be called, in general, hyaline forms or amoebse. As will be explained subsequently, it is only the quartan variety which is found in all its forms mth equal frequency in the peripheral circulation and in the blood of internal organs; whereas segmenting tertian parasites are more abundant in the spleen and bone marrow than in the peripheral vessels, and the sestivo-autumnal parasite develops mainly in the internal organs, its segmenting forms being extremely rare in the peripheral circulation. Each of the forms of the parasite which have been described as developing within the red blood corpuscles may also be found free in the plasma. They probably escape by rupture of the enveloping cor- puscle, a process which one can often witness when examining the fresh blood microscopically. Extracorpuscular mature forms may possibly segment in the usual way, but there is no evidence that forms in the earlier stages may complete their cycle of development free in .the plasma. The important discovery was made by Golgi that all of one genera- tion of the parasite form a group, the members of which develop ^ Plehn claims to have observed that the spores are actively motile and flagellated, but this statement is opposed to the observations of all others.