CERATOMYXA ACADIENSIS. 561 



Fig. 76, Taf. 14, Fig. 77). These two residual nuclei are obviously to 

 be compared with the two trophonuclei of the Disporea. This close 

 parallelism between the Disporea and the Polysporea in the formation 

 of the sporoblasts has been remarked by Doflein ('98, p. 309) . He says 

 in regard to these residual nuclei in the Disporea : " Ich glaube, dieses 

 regelmassige Vorkommen in Verein mit dem unten geschielderten 

 Verhalten verschiedener disporen Formen erlaubt uns in dieser Kern- 

 ausstossung den Ausdruck einer Reduction zu erblicken, und ich werde 

 die beiden Kerne in dem Nachfolgenden als 'Restkerne' bezeichen." 

 Doflein (: 09, p. 762), however, compares the sporoblast of the Disporea 

 with the entire pansporoblast of the Polysporea, a comparison which 

 seems justified neither in the light of the very close parallelism in the 

 number and arrangement of the nuclei in the m;y^osporidium of Cera- 

 tomyxa and in that of the pansporoblast of polysporic forms, nor in 

 the light of the constant relative position of the two sporoblasts in 

 Ceratomyxa, which corresponds precisely to the arrangement in the 

 pansporoblast. 



B. Development of the Sporoblast into the Spore. 



An early stage of the development of the sporoblasts into spores is 

 shown in Plate I, Figures 18, 19, 20, 25. In each of the two sporo- 

 blasts the two cells wliich will later form the valves of the spore-shell 

 are seen enveloping the other cells. These cells will henceforth be 

 called valve-cells. The nuclei of the valve-cells are situated at the 

 opposite ends of the sporoblast (PI. I, Figs. 18 and 20), and are already 

 somewhat flattened. 



Such a cellular origin of the valves of the spore-shell among the 

 Cnidosporidia was first found by CauUery et Mesnil ( : 05) in one of the 

 Actinomyxidae, Sphaeractinomyxon stolci CauUery et Mesnil. A 

 little later this condition was also found in the Myxosporidae simul- 

 taneously and independently by Leger ( : 06, in Chloromyxum truttae 

 Leger) and by Mercier (:06, in Myxobolus pfeifferi). These obser- 

 vations were confirmed by Leger et Hesse (:06) for the genera Myxi- 

 dium, Henneguya, Myxobolus, and later by Auerbach (:07) for 

 different species of Chloromyxum and Myxidium. Leger et Hesse 

 ( : 07) have further found this to be the condition in the new genus 

 Coccomyxa. Sclirdder (:07) has also found it in Sphaeromyxon 

 sabrazesi Laveran et Mesnil, and Awerinzew (:09) in Ceratomyxa. 



In the preparation shown in Figures 18, 19, 20, 25 (PI. I), the last 



