GEFMVIUV^VXIOIV 



OF THE 



ASCOSPORE OF THE TDBER MELANOSPORUM 



EXPLANATION OF THE DRAWINGS 



Enlargement = 1100 



FIG. 1. The ascospore of the truffle at the beginning of the germination; the exter- 

 nal cellular membrane \vhich is brown and covered over with prickles, is reabsorbed on 

 the side of the spore, at an equal distance from the two poles. The way in which this 

 envelope is destroyed allows of its structure being distinguished : it is formed of a layer 

 of polyhedric cells, the prickles which covered over the spore rise to the points of inter- 

 section of the cells; the external surface of these cells is covered over, as well as the 

 prickles, by a thick brown layer. 



When the membrane is being reabsorbed, the prickles at first become dull, and 

 blunt, in such a way as to form small rounded nipples then, according as the brown layer 

 is dissolved, there may clearly be seen the cellular constitution of the membrane, which 

 is light yellow, such being the colour of the cells. 



FIG. 2-3. - - The external membrane is completely reabsorbed over a certain surface 

 and its cellular tissue destroyed. The germinal ampulla which was inside the ascospore, 

 and which is limited by a colourless membrane projects outside the rigid brown enve- 

 lope surrounding it : in its growth it tends to become spherical in form. 



FIG. 4-5. -- Section view of the ascospore at the moment of the extension of the 

 internal germinal ampulla, the external membrane is thicker in the vicinity of the poles 

 of the spore than on the rest of the circumference : the cellular structure may easily 

 be distinguished. 



FIG. 6. A germinal ampulla which has dilated and still bears on its surface a few 

 un-reabsorbed nipples, coming from the external brown envelope of the spore. 



FIG. 7. -- During the growth ol' the germinal ampulla, the external envelope which 

 has not been reabsorbed, has remained applied on the membrane of the ampulla : it is 

 thus rejected to the back of the sphere formed by the extension in one direction of the 

 ampulla. The reabsorption of the brown envelope continuing, there soon remains no- 

 thing of the latter except two hemispherical calottes, separated from one another and 



