INCUBATION — GKOWTH OF THE SPORES. 



213 



Fig. 111. — Development of 

 Psorosperms in Coccidia. 



But these segmentation-spheres very soon assume another shape, 

 changing from a spheroidal to an ovoid form, and pressing to the 

 side the clear plasma which was formerly 

 wholly surrounded by the granular mass, and 

 which had also been increasing at the expense 

 of the latter. The substance of the segmenta- 

 tion-spheres undergoes a further differentia- 

 tion, and produces finally a transparent curved 

 C-shaped rod. A thin, but tolerably firm, sur- 

 rounding envelope is at the same time secreted. 

 The rod lies with its convex surface on this 

 above-mentioned envelope, while its concavity 

 embraces the remainder of the granular mass, drawn together into a 

 minute ball (0'005 to 0006 mm.), and presenting the appearance of 

 an embryo and its yolk-sac (Fig. 112). I have no scruple in regarding 

 the latter as the so-called " nucleus de reliquat," and the rod as the 

 proper reproductive body. 



The description which Stieda gives of these Psorosperms is in 

 perfect harmony with my observations. I must specially note my 

 agreement with him on this point, that the rod consists of a uniform, 

 perfectly hyaline substance, and is swollen at its ends into a strongly 

 refracting ball, which perceptibly exceeds the diameter (O'OOS mm.) 

 of the connecting part. When this connecting part lies in the direc- 

 tion of the optical axis, as not unfrequently happens, one sees only 

 the two terminal knobs of the rod, which, with the intermediate 

 granular ball, form the figure described by Lieberkiihn, ^ according to 

 whom the contents of the Psorospermice consisted of two transparent 

 polar bodies, separated by a granular ball. This view is of course 

 dissipated when the object is seen from the side. 



The newly formed rods (Fig. 112, £) have by no means that 

 strong refractive power which they afterwards acquire. Even 

 the little heads are still feebly lustrous, and present essentially 

 the same appearance as the plasma enclosed in the former segmen- 

 tation-spheres. 



The representation which Eeincke gives of the rods differs in so 

 far as he denies their homogeneous nature, and describes three or four 

 " globuli ccsrulei in modum cerse lucentes," lying behind one another, 

 which are sometimes so large that they fill up the whole diameter. 

 Two of these structures represent the heads of the rods ; the others 

 the thinner median portion. 



I have seen forms which bore out the above description, in so 

 far as the heads sometimes seemed as if disjointed, and the median 



1 MuUei-'s Arcliiv[Ji^ti^d-i^M^r($S&f(!®>- "•, T'ig- 37, 1864, 



