226 



THE SPOROZOA 



termed microgametocytes of the second order, and each of which gives 

 rise to numerous microgametes. Hence in this form the correspondence 

 between the ordinary schizogony and the formation of the microgametes 

 is very exact (see above, p. 223). 



The microgametes vary greatly in their characters. Only 3-4 p. long 



FIG. 57. 



Conjugation of Coccidium proprium, A. Schn. (par. Triton), after Siedlecki [53]. a, penetra- 

 tion of a microgamete (<$) through the micropyle (mp) of the tough oocyst (ode), by which the 

 female gamete is surrounded. The ? gamete only partially fills the oocyst, which it only 

 touches at the micropyle. Its nucleus (n) has lost its membrane, and is pear-shaped, with ill- 

 detined limits ; it touches the micropyle by one of its extremities, and at the opposite extremity 

 the chromatin (?) is aggregated in the form of a number of little rods round a central karyosome. 

 b, the microgamete after penetration breaks up into a mass of chromatin ( & ). The macrogamete 

 has withdrawn from the micropyle, leaving a plug of protoplasm (p) attached to it, which closes 

 the aperture. Two vacuoles (vac) have appeared in the macrogamete, containing each a little 

 chromatic sphere, perhaps derived from the karyosome. c, a fertilisation-spindle is formed, in 

 which the & and 9 chromatin granules are commingled. The two vacuoles have fused into a 

 single one, which persists throughout the sporulation, and is left in the residuary protoplasm 

 of the cyst, d, e, f, the nucleus of the zygote (n.zyg) becomes compact (d), then divides into 

 two nuclei (e, f), and finally into four. 



in Coccidium lacazei, they reach ten times that length m Klossia, but in 

 each case are scarcely 1 p in breadth. The ftagella weie first discovered 

 by Leger in the microgametes of Barroussia caudata, Leger, from Litlwbius 

 martini, and in other forms. They have now been demonstrated in a 

 number of species ; and though usually two in number, they may vary 

 in position ; in the above species of Barroussia and in Coccidium oviforme 

 of the rabbit, both flagella are attached to the anterior end of the gamete. 



