REMARKS ON THE PILOBOLIDAE 185 



of the higher animals. These patterns are very regular ; a chief 

 alveolus occupies the centre at the top of the globule (sporangium) 

 and six other exactly similar cells are placed around the sides of the 

 principal polyhedron. These alveoli have shades of coloration, 

 their centre is usually pale, and a colourless or paler streak separates 

 them from one another. I have noticed similar patterns, but ovoid 

 in form, on the sporangium of Ascophora Cesatii ^' {= Pilaira 

 anomala). 



" It is remarkable that these patterns are not produced regularly 

 each year. In 1859, in a hot summer, they ornamented all the 

 globules of Pilobolus crystallinus that I 

 observed ; in 1860, the summer being cold 

 and wet, I found them very rarely and 

 always faintly indicated. The cause of 

 these variations is probably connected with 

 the effects of light and heat. It may also 

 be noted that, the irregularity of the appear- 

 ance of these patterns being proved, they Fig. 92.— Pt/ofco^ws crys- 



^ o J. ' »/ talhnus. Sporangium 



cannot have any diagnostic value." flattened out and seen 



_. . 1 • -n i i • 1 l^ from above. Copied 



Coemans m his illustrations shows the by the author from 



pattern on a discharged sporangium (Fig. 92), ^^^/raleif Mag! 



but not on sporangia still seated on sub- nification increased 



,,. rru • A from 220 to 293. 



sporangial swellings. Ihere is good reason 



to suppose, therefore, that Coemans saw the pattern on discharged 



sporangia only. 



Van Tieghem,^ in his description of Pilobolus crystallinus, says : 

 " A white network with the meshes most often hexagonal ornaments 

 the upper surface of the cuticularised hemisphere (sporangium) ; 

 there is a hexagon at the top and six other hexagons arranged in 

 a circle around the first with their free sides rounded below. Some- 

 times the central polygon has four, five, seven, or eight sides. This 

 regular system of white lines, left untouched by the coloration which 

 affects all the rest of the cuticularised hemisphere, is quite charac- 

 teristic of this species." Van Tieghem, in a foot-note, adds : that 

 he has found the network in all the sporangia of P. crystallinus 



1 P. van Tieghem, " Troisieme m^moire sur les Mucorinees," Ann. Sci. Nat., 

 6 ser., T. Ill, 1876, p. 336. 



