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V. DISCUSSIONS. 
19. Questions regarding the Parasites. — Having recorded our observations in Free- 
town, we propose next to consider some questions of importance in connection with our subject. 
The Hfe-history of the Haemamoebidae as now known, and as given in the terminology 
previously adopted by one of us in consultation with Professor Herdman [15], is as follows 
[Platrs /., //., ///., IF.-] :— 
The youngest parasites exist as amcebula or tnyxopods within the red blood-corpuscles 
of the vertebrate hosts. On reaching maturity they become either sporocyteSy ox gatnetocytes. 
The sporocytes are destined for the asexual propagation of the organisms within the 
vertebrate hosts. They give rise by division to spores ; which escape into the plasma, enter 
fresh corpuscles, and in their turn become amoebulae — thus continuing the species indefinitely 
in the blood. 
The gametocytes, however, are sexual forms, male and female — the male containing 
a number of microgameta ; the female, one macroganiete. They remain unchanged within the 
vertebrate hosts ; but on being drawn into the stomach of a suctorial insect, perform their 
sexual function. The male gametocyte emits its microgametes ; one of which enters a macro- 
gamete and fertilizes it. The fertilized macrogamete is called a zygote. 
If the suctorial insect be a species hospitable to the parasite, the zygote next escapes 
from the contents of the stomach, pierces the wall of the organ, and affixes itself in or on 
the outer coat. Here it grows largely in bulk. Its substance divides into from about eight 
to twelve meres. Each mere becomes a hlastophore bearing a large number of filamentous 
blasts affixed to its surface by one extremity. As growth advances the blastophores disappear, 
leaving the capsule of the zygote packed with the blasts. The capsule now ruptures, allowing 
the blasts to escape into the body-cavity of the insect. From this they work their way into 
the insect's salivary gland ; and finally pass from this gland into the blood of a new vertebrate 
host, in which they eventually become the amoebulae with which the cycle commenced. 
As to terminology — it will be perceived that we use the word " spore " for the asexually- 
produced progeny of the parasites, and the word " blast " for their sexually-produced progeny. 
Originally, however, neither word possesses such restricted meanings: a "spore" is a single cell 
capable of separating from the parent and of starting by itself a new bion or individual ; while 
" blast " simply means a bud. Considering, however, that the recent demonstration of typical 
sexual functions among the Coccidiidae and Haemamcebidas originates the new case of such 
functions (apart from simple conjugation) among unicellular animals, it may be now justifiable 
