23° 



HA RD IV J CKK S SCIENCE- G OSSIP. 



Polystigma rubrum, bodies similar to these spermatia 

 • are., to say the least, strongly suspected of performing 

 the alleged function. 



This is all that is produced of the fungus so long 

 as the leaf remains attached to the tree ; but after its 

 fall further changes begin to take place. This is 

 shown by a thickening and blackening of the affected 

 part of the leaf, so that about the succeeding March 

 the under surface of the leaf is also blackish, and the 

 mass of mycelium doubles or trebles the thickness of 

 the leaf. The upper surface of the spot, which 

 at first was dull and even, now becomes shining and 

 wrinkled ; and in May it assumes the form represented 

 in Fig. 151. The elevated flexuose wrinkles then open 

 along the crest, and the edges of the cracks roll back, 

 thereby exposing the dull whitish hymeni.il disc 

 which has been gradually forming itself beneath. 



It is probable that the production of spermatia 

 ceases in the autumn, and that (whether in conse- 

 quence of any act of fertilisation or not) the mycelium 

 encloses itself in its dense hard black covering, so as 

 -to last through the winter, in fact, to hybernate. 

 Then in spring it commences to grow again, but this 

 time the upturned edges of the hyphte, instead of 

 abstricting spermatia, grow out into the sac-shaped 

 bodies called asci (Fig. 152), which are at first filled 

 with a dense granular protoplasm. These proto- 

 plasmic contents finally resolve themselves into eight 

 elongated-fusiform colourless sporidia, which are 

 nearly as long as the ascus itself, and sometimes more 

 or less spirally incurved at the summit. 



When the perfect hymenium is exposed by the 

 turning back of the edges of the fissures, the asci are 

 ruptured (presumably by the continually increasing 

 pressure of the new ones which form around them) 

 and the sporidia are ejected, as Tulasne says, "like 

 smoke." If the latter are then placed in suitable 

 moisture they will germinate by sending out a 

 mycelial thread ; and if they happen to have been 

 blown on to the moist surface of a young sycamore 

 leaf, the hypha will penetrate into the tissues 

 (probably through a stomate), and the cycle of 

 development will begin again. If not, they simply 

 perish. 



It will be seen that the ejection of the sporidia 

 occurs just at the time when the young sycamore 

 leaves are bursting from their buds. In fact, the 

 whole life-history of the fungus, like that of so many 

 others, has adapted itself to our climate. The fungus 

 is an annual one, and if all the affected leaves could 

 be destroyed in any autumn it would not reappear in 

 the succeeding spring. The same is true of Rhytisma 

 salicinum on the leaves of willows ; but R. maximum, 

 which occurs on willow branches, has a different 

 history. It is, I believe, perennial ; the sporulcs 

 appear in spring, and the sporidia in the succeeding 

 summer. 



The only point in the life-history of Rhytisma 

 accrinum which remains obscure is the function of 



the spermatia, of which, as I have said, I believe 

 nothing is known. It may be that, like the uredo- 

 spores of Fuccinia, they simply enable the fungus to 

 spread more rapidly, by germinating and producing 

 fresh spots on other leaves to which they may have 

 been carried. It may be, on the other hand, that 

 they are in the position of so many other similar 

 bodies, of having retained the form but lost the 

 function of spermatia. It is now well known that a 

 complete sexual union occurs only in a comparatively 

 few, chiefly of the lower forms of fungi ; as we rise in 

 the scale the reality of the act gradually becomes less 

 and less. The exact form of the sexual organs may 

 even be retained after they have become functionally 

 impotent : the pollinodium may attach itself to the 

 oosphere, but if no fusion of the protoplasms takes 

 place no fertilisation can be said to exist. The 

 performance is but a shadow-play. 



Even this morphological semblance of sexual 

 organs becomes gradually less distinct, and finally in 

 the highest fungi disappears entirely. In the Hymeno- 

 mycetes not even a trace of sexuality is known ; and, 

 what is more, the whole bearing of modern discoveries 

 goes to show that this want of knowledge is not due 

 to any want of observation on our part, but merely 

 to the fact, that there are no traces of sexuality to 

 discover. Nor is the philosophy of their disappear- 

 ance, I fancy, hard to find, but to pursue the subject 

 now would lead me to too great a length. 



W. B. Grove, B.A. 



Birmingham. 



MOLE'S EYES. 



THE commonly received fallacy, that moles are 

 blind, is of so respectable an antiquity as to 

 date back to the time of Aristotle, B.C. 384. 



That great man, of whom Plato spoke as "the 

 intellect of the school," spent much of his time in 

 dissecting animals, and wrote an enthusiastic book 

 upon the subject. But he blasted the reputation of 

 the mole, and his statement has been more or less 

 reverently received for 2270 years. Here is con- 

 servatism with a vengeance ! One is hardly surprised 

 to find ordinary people speaking carelessly of the 

 mole as blind. To all appearances, it is not only 

 blind, but eyeless, and those only who have either 

 dissected or immersed the creature in water, have 

 been permitted a sight of the small black eyes which 

 can be retracted or exserted at will. But mistaken 

 casual observers will find themselves in good company. 

 Greater minds than theirs have been deceived, and 

 poor Talpa, who might have been proud to find the 

 pen of a Carlyle, a Matthew Arnold, and later still a 

 Drummond, shaping the letters of his name, has to 

 accept the ugly fact as it stands, that but for his 

 supposed deficiency, they would never have troubled 

 their heads about him. 



