80 DIVISION I. GENERAL MORPHOLOGY. 



of spores in these instances differs from that in the 8-spored asci in no other respect 

 than in the number of nuclear divisions and spore-primordia. Whether regular 

 abortion of a certain number of original spore-primordia occurs in individual cases, 

 where the number of perfect spores is small, is still uncertain. The formation of the 

 spores too in Tuber and doubtless also in the rest of the Tuberaceae and in 

 Elaphomyces differs much less from that in asci with 8 spores than appeared from 

 my former observations, which were conducted with imperfect means. There also 

 we find simultaneous orientation of spores and nuclei. The inequality in the number 

 of the spores is due partly to the inequality in the number of the original spore- 

 primordia or divisions of the nucleus, partly to the frequent want of uniformity 

 in later developement and to the partial disappearance of spores after they are once 

 formed. 



In the full-grown stalked spherical ascus of Tuber (T. aestivum, T. melanosporum, 

 T. brumale (Fig 40) and their allies) the protoplasm which is at first irregularly granular 

 and interspersed with vacuoles becomes differentiated into a dense parietal strongly 

 refringent layer of glycogen, which turns a brownish red with iodine, and an excentric 

 spherical cavity filled with finely granular weakly refringent protoplasm which becomes 



FIG. 40. Tuber trumalt, Vitt. Full-grown asci isolated in water, a protoplasmic cavity separated from the layer 

 of glycogen. 6 six young spores visible in the protoplasm, c shows one spore half matured and two which have remained 

 quite small in the same position. Magn. 390 times. 



yellow with iodine. The limiting layer of the glycogen-mass is very compact where it 

 borders on the cavity, and its double contour is often so sharply defined that older 

 writers supposed it to be the membrane of a special cell. The spores are formed 

 in the protoplasm. Observations made by Errera have shown that there is one 

 nucleus in the protoplasm, visible even in younger asci, which by successive 

 divisions gives rise usually to 4-6 nuclei ; then as many spore-primordia appear 

 simultaneously and in close proximity to one another round these nuclei in the form 

 of small and very delicate cells. As the cells now begin to grow they move further 

 apart and usually develope unequally, some outstripping the others, while some remain 

 stationary at an early stage of development and at length disappear. Hence the 

 frequent occurrence of quite delicate spore-primordia with others that are far advanced, 

 which once led me to suppose that they were formed successively, and hence also 

 the unequal number of ripe spores, varying from 1-4-6 in an ascus. The old drawings 

 reproduced in Fig. 40 will sufficiently illustrate the subject for the present. 



The asci of Elaphomyces granulatus are of similar form to those of Tuber, and 

 contain before the orientiation of the spores a very transparent protoplasm forming 

 a thin parietal layer round one or more vacuoles and turning yellow with iodine ; no 

 glycogen-mass appears in them. I found in the lower third of a half-developed ascus 

 where the great increase in breadth begins, a small but distinct nucleus with the 



