1 88 STRICKLAND : NOTES ON FUNGI. 



containing a quantity of spiral threads and disc-like spores, or a more 

 or less rounded or cylindrical capillitium of anastomosing threads 

 with a mass of spores entangled among the meshes. Now here, 

 surely, it is not any mysteriously inherited properties in the fungal 

 protoplasm which are responsible for the characteristic form of the 

 mature plant, but something much stronger than any law of inheri- 

 tance — the ever present law of gravity which determines both the 

 spherical form of the globules of dew and that of the minute paste 

 specks of the nascent fungus ; or again, look at the army of species 

 of Sphaeriae and Pezizae, almost all of them parasitic and very many 

 of them parasitic upon specific hosts. Let us take two well-marked 

 species, Sphceria moriformis, a small black species (almost all Sphaeriae 

 are black or brown) and Sphceria acuta. Sphceria moriformis grows 

 on dead wood and has a wrinkled perithecium like a mulberry : 

 Sphceria acuta has a smooth perithecium ending in a sharp but not 

 attenuated nib like a bullfinch's. The normal form of the sporidium 

 in S. moriformis is a long shuttle-shaped cell, rounded at each end and 

 with a single septum in the middle of it. But occasionally sporidia 

 of exactly the same shape are found with six or seven septa. 

 Sphceria acuta, on the other hand, has a sporidium of much the same 

 shape and size as that of S. moriformis, but the common form is 6-7- 

 septate. There is, however, a less common form of sporidium of 

 exactly the same shape as the polyseptate one, but with only a single 

 septum in the middle. The abnormal fruit of S. acuta is in fact the 

 same as the normal fruit of S. moriformis ; the abnormal fruit of 

 S. moriformis is the same or nearly the same as the normal fruit of 

 S. acuta. Does not this lead one to suspect either that the two species 

 are descended from some form frequenting all sorts of decaying 

 wood, like Sphceria moriformis, Sphceria acuta being the more 

 specialised descendant, or, that when the sporidia of either form are 

 sown on different hosts under such conditions that they germinate, 

 the perithecia become Sphceria moriformis on dead wood and 

 Sphceria acuta on decaying nettle-stems ? Here again I would ask 

 what is the exact effect of the host on the form of the fungus 

 parasitic upon it ? Is Sphceria acuta nibbed because it is of direct 

 advantage to it to be nibbed, or is its conical form a by-effect of the 

 juices of the host upon the parasite which certainly thrives upon 

 nettle-juice, for it is one of the commonest of British Sphaeriae. 



Let me take as a final instance one of the minute Pezizae which 

 grow upon dead wood. And let me first premise that the colour of 

 the spores and the sporidia, and very frequently of the whole plant 

 in fungi, is constant enough to be one of the most useful means of 

 discriminating between species. Thus the great group of agarics are 



Naturalist, 



